Cutler-Hammer Spot Network Equipment

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January 2003

Contents

Spot Network Equipment17

Ref. No. 0453

S p o t N e

t w o r k

E q u i p m e n

tDescription Page

Spot Network Equipment

Discussion

Decision Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0-2

General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0-3

Commercial Spot Network Design Considerations . . . . . . . . . . . . . . . 17.0-5

Network Protector Equipment

CMD Network Protector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1-1

MPCV Network Protector Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1-7

CMD Network Protector Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1-11

CM52 Network Protector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1-12

Rating Selection

Spot Network Equipment Selector Guide . . . . . . . . . . . . . . . . . . . . . . . 17.2-1

Protector Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2-3

Layout Dimensions

Liquid Type Network Unit Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . 17.3-1Dry-Type Network Unit Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.3-2

Dry-Type Network Unit —Switchgear Mounted Protector Dimensions . . . . . . . . . . . . . . . . . . . 17.3-3

Specifications

For complete product specifications in CSI format seeEaton’s Cutler-Hammer Product Specification Guide. . . . . . . . . . . . . Section 16422

CMD Network Protector CM-52 Network Protector

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Discussion

Spot Network Decision TreeRef. No. 0454

Figure 17.0-1.Spot Network Decision Tree

Considering Spot Networks for

Electrical Distribution in a Facility?

Does the local utility

offer multiple circuits for

the metered utility service?

YES NO

Are the multiple incoming

circuits from the utility

in synchronization?

YES NO

Are the multiple circuits from the utility

the same voltage and frequency under

most operating conditions?

YES NO

How many circuits are available or routed to each major load areas of the facility?

One (1) Two (2) Three (3) Four (4)

Use Radial design at one

or more service voltages.

Use separate Radial

or Double-ended

Substations with Open

Transition Switching.

Spot Networks may be

possible, but without the

redundancy of multiple

primary circuits.

Spot Networks may be

possible, but without the

redundancy of multiple

primary circuits.

Two Transformer Spot

Networks are practical.

See Pages 17.2-1 through

17.2-3 for Application

information. If anticipated

load = X kVA, use two

network transformers

each rated X kVA.

Four Transformer Spot





load = Z kVA, use four


each rated Z/3 kVA.

Three Transformer Spot





load = Y kVA, use three


each rated Y/2 kVA.

Continuity of

Service Critical

Continuity of

Service NOT Critical

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17January 2003

Spot Network EquipmentDiscussion

General DescriptionRef. No. 0455

Description

Eaton’s Cutler-Hammer Spot NetworkSystems are designed to ensureservice continuity in 208/120V and480/277V wye connected secondary

network systems. These systems,in either grid or spot network form,are commonly used in areas of highload density such as metropolitanand suburban business districtsor facilities.

Suburban loads were formerly almostentirely residential and power outagescaused little more than personal incon-venience. Now, the suburban loadincludes not only shopping plazas,industries and residences, but suchvital facilities as hospitals and airports.For these and other critical loads,power interruptions can have seriousconsequences to public and personal

safety. Spot networks provide superiorreliability at these important loads.

The need to supply increasing amountsof power efficiently, without increasingequipment size, has resulted in a shiftfrom 208V to 480V wye systems. Thechange to a higher utilization voltagerequires a commensurate change inoperating procedures because of thedifference in arcing characteristics at480V compared to 208V. For example,while an arc in a 208V system isnormally self-extinguishing, an arcin a 480V system will usually burnuntil it is interrupted by an overcurrent

device or until it totally consumesthe arcing material.

Secondary network systems usingCutler-Hammer Network Protectorsare among the most dependable inuse today. In the event of a fault on aprimary system cable or transformer,the protector opens due to reversepower flow, thus isolating the faultfrom the network bus and avoidingload power disturbances. Loss of the primary feeder will not result inservice outage at the load on thesecondary network. The other primaryfeeders will continue carrying the loaduntil the faulted cable is repaired and

returned to service.

The network protector basically con-sists of a special air power breaker,a breaker operating mechanism, net-work relay(s) and control equipment.Units are available in both weather-proof and submersible enclosures foreither separate or transformer throatmounting. Switchgear mounting isalso possible.

Figure 17.0-2.Typical Configuration for Three Transformer Spot Network

Better Continuity of ServiceThe largest user of network systems

in the United States is ConsolidatedEdison of New York. Historical datadeveloped by this utility illustrates thatoutages are very rare (approximatelyzero) on grid systems and that spotnetwork systems are five times morereliable than secondary selectivedouble-ended substation services.

Improved Regulation —Less Voltage SaggingEach load is supplied from at least twodirections. Services supplied from atransformer location have a minimumof two paths of supply on utility grids

and spot networks, and can bedesigned to have more. Abruptchanges in loads, such as motorstarting, cause much less voltagedisturbance due to the multiple pathsfor load current compared to simpleradial services. The voltage dip result-ing from a given starting current maybe 70% less in a network system thanin a radial system.

Less Transformer CapacityRequiredIn normal operation, the loads alongthe network service are divided among

the various network transformers insuch a way that the best possiblevoltage conditions and lowest lossesare realized. Since all the services aretied together, many more loads aresupplied from the same secondarynetwork source than in a simple radialsystem. The peak loads on the trans-formers are correspondingly lower inthe network system compared to a

radial system supplying the sameloads, because of the diversity in the

demand among the larger number of circuits. Therefore, less transformercapacity may be required in a networksystem than in a radial system in thesame area, particularly if three ormore primary feeders supply thenetwork system.

System OperationA short circuit on any one primaryfeeder will cause all the networkprotectors on that feeder to open onreverse energy, provided the totalpower on the 3-phase feeder is inthe reverse direction. When the feedercable is repaired properly, the network

protectors on that feeder will auto-matically reclose when the feedercircuit breaker at the upstream switch-gear is closed, if correct voltage condi-tions exist at the network transformer.

If the phases are reversed during thecable repairs, the protectors will notreclose automatically as long as thenetwork remains energized. Likewise,if a voltage less than network voltageis restored to the feeder, the networkprotector on that feeder will notreclose automatically. The unit couldbe closed manually if the networkrelay trip contact is not closed.

If a feeder from a separate source is tobe connected to an energized network,the incoming voltage must be slightlyhigher than the network voltage andin proper phase relation with it. If afeeder is being connected to a deadnetwork, it is sufficient to have theincoming voltage high enough tooperate the closing mechanism.

Customer

Loads

Customer

Loads

Customer

Loads

NC NC

TieTie

Typical Feeder

To OtherNetworks

Low VoltageSwitchgearDrawout

Fuses

Primary Circuit

Network Transf ormer

Protector

Optional Main, 50/51Relaying and / orNetwork Disconnect

LV Feeder

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General DescriptionRef. No. 0456

Maintenance of primary feeder circuitscan be accomplished by openingupstream switchgear primary devicesone at a time, thereby opening everyprotector connected to a given primarydue to reverse magnetizing currentsflowing through each protectorserved. By opening the primarycircuits one at a time, the networkloads are not disturbed. Also, at timesof light load, the system can beeconomically loaded by disconnectingsome of the primary circuits andoperating the transformers at moreefficient levels. Although the protec-tors are capable of opening underreverse magnetizing currents, theopening may be delayed dependingupon the time delay setting of thenetwork relay.

When the load increases on the net-work, other primaries can be brought

into service by closing the feederbreakers. The associated protectors onthe reactivated feeders will recloseserving the network if the transformervoltage is higher than the networkvoltage by a certain minimum amountand in the proper phase relation.

The network protector fuses providebackup protection for clearing faultson the primary feeder in the unlikelyevent the protector fails to operate.These melting alloy or partial rangecurrent limiting fuses are located onthe load side of the protector, andwhen removed, serve to isolate the

protector from the network.Numerous protector models areavailable from Eaton’s Cutler-Hammerbusiness and the best product for theapplication is a function of the type of system being designed: utility grid (see Figure 17.0-3) or spot network. Spotnetwork systems (see Figure 17.0-2)usually use the Cutler-Hammer CM52or CMD type of protector, which hasimportant safety features not foundon earlier models. These features arebriefly explained in Pages 17.1-1 and 17.1-12.

Figure 17.0-3.Typical Configuration for Utility Grid Network

CMD Protector Advantages

CMD Protector

Exclusive Drawout Design: Withpositive safety interlocks, providesmaximum protection against contactwith energized components whiledisconnecting the unit for test ormaintenance; ensures maximumsafety for operating personnel. All

main current carrying and mechanicaloperating components are locatedbehind a deadfront steel panel whichminimizes the possibility of tools orhands being inserted into an energizedprotector. The drawout unit isoperated by a hand-cranked leveringsystem, which cannot be engagedunless the circuit breaker is openand cannot be disengaged unlessthe drawout unit is either fullydisconnected or fully connected.

Modular Construction: Simplifiesfield maintenance and/or replacementof components. Protectors can bequickly put back into service reducingmaintenance time.

Spring Close Operating Mechanism: Avoids partial closures. The CMDspring close mechanisms will notpermit closing motion of the contactsuntil the closing springs are fullycharged. Also provides close and

latch ratings on protectors.Externally Mounted Silver-Sand Fuses:Operate with no contamination of the protector, and will positivelyinterrupt fault current to disconnectthe protector from the network busin abnormal fault situations.

Low Energy, Capacitor-Trip Actuator:Provides reliable tripping effort, evenwhen system voltage is not available,up to four operations via remote trip-ping before recharging is needed.

Close and Latch Ratings: Comparableto air power breakers are readilyavailable since the mechanism isstored energy, unlike motor operatedprotectors which have no close andlatch ratings.

Increased Dielectric Strength: CMDunits have passed a more stringentdielectric test voltage of 5000V ACcompared to the lower value of 2200V required by ANSI standards.

Typical NetworkTransformer

Grid

LOADSLOADSLOADS

LOADSLOADSLOADS

LOADSLOADS

Grid

TypicalProtector

Primary FeederBreaker

LOADS

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17January 2003


Commercial Spot Network Design ConsiderationsRef. No. 0457

Commercial Spot NetworkDesign ConsiderationsThis section deals with the variouscomponents which make up thecommercial spot network, either as adouble-ended substation or multipletransformer substation. The intent of the discussion is to give some basicguidelines for the selection of Eaton’sCutler-Hammer transformers and net-work protectors. The major compo-nents that will be discussed are:

1. Primary Switches.

2. Network Transformer Types.

3. Network Protectors.

4. Spot Network Disconnects.

5. Low Voltage Drawout SwitchgearConfigurations.

6. Typical Spot Network Layouts.

7. Use of Current Limiting Fuses.

8. Network Device Coordination.

1. Medium Voltage PrimarySwitches

The incoming medium voltage feedermay range from 4160 volts to 34.5 kV.Any feeder which has a voltage higherthan 34.5 kV should not be consideredfor spot network service because thecable charging capacitance begins toaffect the operation of the networkrelay response. The primary feeder

enters into a switch compartment,which can be liquid or air type. Theliquid type transformers usually usea special three-position liquid-filledprimary switch, which has a specialthird position for grounding theincoming feeder cable during mainte-nance work on a primary circuit.Dry-type transformers usually use atwo-position air switch, which omitsthe third position. Grounding thecircuit becomes a manual procedure,if needed, on dry-type transformers.

The three positions of the liquidtype switch on liquid network trans-

formers are:1. Close.

2. Open.

3. Ground.

Figure 17.0-4.Three-Position Primary Switch Interlock for Liquid Network Transformers

These switch designs utilize electrical

interlocks which prevent the uninten-tional movement of the switch, witheither the network protector in the“Closed” position or the mediumvoltage feeder being energized. Figure17.0-4 shows the typical electrical con-nections for the interlocking betweenthe primary switch, transformer andnetwork protector.

Coil #1 and #2 are electrical interlockswhich prevent unsafe operation of theprimary mag-break switch. Coil #1ensures that the protector must beused to break load current beforeoperating the switch from closed to

open. Coil #2 ensures that the primarycable must be deenergized beforeoperating the switch from closed toground. These interlocks are notnecessary on a two-position air switchif it has loadbreak ratings. If a three-position air switch is used includingthe ground position, then the interlock-ing is once again mandatory.

Due to their common use, liquid typenetwork transformers are manufac-tured with the three-position mag-break switch integral to the trans-former. Dry-type transformers utilizethe commonly available two-positionair switch with special flicker blades

which give the air switch a loadbreakrating. The capability of interruptingload currents can save time by nothaving to deenergize the feeder. Thechoice of switch type is thus dictatedby the type of transformer selected forthe spot network system.

Another consideration is the necessity

to provide primary overcurrent protec-tion for each transformer, such as in theform of power fuses. Upstream breakersusually serve two, three or four trans-formers on their circuit and thus havethe protective relays set at higher levelsdictated by the entire circuit load, whichsacrifices individual transformer protec-tion. See Figure 17.0-13 later in thissection for a specific example of thistype of situation. When dry-type unitsare used, one solution is to add powerfuses to the loadbreak switches.However, this option is not easy whenliquid types are used unless air switchesare added ahead of the integral type

liquid switches. If fuses are used any-where in the primary circuit, the networkprotector relays must be capable of trip-ping under WATT-VAR conditions. Newsolid-state type network relays have theability to configure their tripping charac-teristics from WATT to WATT-VAR in thefield. Older type protectors having elec-tromechanical relays should be updatedby retrofitting with the newer relays.If fuses are not present, the standardWATT trip characteristic, which isstandard in the industry, is appropriate.

Each type of primary switch usesunique terminations of the primary

cable. Liquid switches use a terminalchamber which is filled in the fieldwith a suitable compound to improvethe insulation strength of the cables.Air switches utilize mechanical orcompression terminations withstress cones.

Interlock logic can varythus both an A and Bauxiliary contact issupplied.

ab

Primary Mag-

Break Switch

Network

TransformerOpen

Closed

GroundPosition

Protector Fuses

To Network

Coil #2 Interlock

Coil #1 Interlock

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Air switches require slightly more floorspace than the integral liquid type of switch, especially since the depth of the air switch is made to match thedepth of the transformer. Transitionsections add to required floor spaceif hard bus connections, not cable,are required. Whereas the three-position liquid switch dimensions areno greater than 20 inches (508.0 mm)deep off the end of the transformerand 30 inches (762.0 mm) in widthcentered at the end of the unit.

It is possible to use both types of switches for liquid installations.Groups of air switches can bemounted along a wall to receive anddistribute primary circuit power toeach transformer. Individual powerfuses can be mounted within the airswitches. Dry-well mounting of currentlimiting fuses in air canisters accessi-

ble from the top or side walls of thetransformer is not recommended.The available space will dictate muchof the design if sufficient space isnot allocated and kept for electricalsystem equipment.

Primary switches accommodatethe 3-phase conductors and neverutilize a neutral conductor. Most spotnetworks use delta wound transform-ers, so there is no need to deliver theneutral through the primary switch.Any type cable can be used, howeverthe more modern types are easier tohandle than paper lead insulated types

which require potheads for termina-tions within the primary switch.

2. Network TransformerCharacteristics

After the primary switch, the power isdelivered to the primary windings of anetwork type transformer. The designmay be liquid- or dry-type, with liquidtypes being more popular from ahistorical perspective, due to theirapplication in utility systems.However, dry-type designs are nowavailable meeting the ANSI networkstandards. Most applications withincommercial buildings desire dry-typedesigns due to the desire to avoidthe fire hazard associated with liquiddielectrics. It is important to useproper dry-type ratings which mimicthe overload characteristics of liquidunits, therefore dry types should berated for 80°C rise and use Class Hinsulation materials. Fans are normallyemployed to aid the air cooling duringperiods of overloading, and may occurduring a single primary outage.

Secondary voltages are always 480Vor 208V wye. Also, 216V wye is acommon rating. Primaries arealways delta, such as 4160, 13.2 kV,13.8 kV, etc.

Transformer impedances should fall

within the standard ranges below, orelse the usual protector ratings maybecome inadequate. If impedancesdrop below the values below, the max-imum through-fault may exceed theinterrupting rating of the protector.Also, the impedance values amongtransformers in a spot network shouldbe as close in value one to the otherthat manufacturing tolerances willallow; this helps reduce circulatingcurrents between transformers.

Table 17.0-1.Transformer Impedance

Notice that 2500 kVA is typically thelargest transformer that can be usedfor network services.

As an example, let’s assume we are todesign a two-unit spot network usingdry-type transformers having 80°Ctemperature ratings. In this examplewe calculate that the building load willnot exceed 1495 kVA. Since we aredesigning the service as a double-ended network substation, eithertransformer must be capable of carrying the full building load of

1800 amperes.

One choice is to select a 1500 kVAtransformer size which has a full loadrating of 1805 amperes. However, inspecifying transformers for networkservices, the units can be undersized,realizing that under most conditionsboth units are available to supplypower to the network. When only oneis handling the entire load, it should beconsidered an abnormal event thatshould not continue indefinitely.

For our load of 1495 kVA, a 1000 kVAtransformer will supply 1805 amperesat 150% of nameplate rating, therefore

we would select a 1000 kVA dry-typeunit with 80°C rise with fans (150%overload capability) and a protectorwith a continuous rating of 1875amperes.

In all spot network designs, the equip-ment must be sized to handle the loadeven though one primary, and thusone transformer, is out of service(known as a single contingencycondition) for some period of time.The basic design constraint is that theload not exceed the maximum thermalrating of the remaining unit(s) duringthe time of the single contingency.Protector ratings recommended byvendors, as well as protector circuitry,anticipate the loads and are sized tohandle the higher currents, so thelimiting factor is the transformer.

One advantage of liquid designsis their large thermal mass whichenables them to handle highercurrents for a longer period of timewithout the need for an FA fan ratingwhen compared to conventional 150°Crise dry-type designs. When both

transformers are available, the 1000kVA units in our example will only beloaded to 75% of their AA base rating.

The transformer winding configurationwill depend upon the primary serviceavailable and the type of serviceneeded by utilization equipmentcomprising the loads. For the mostpart, transformers are DELTA-WYE,which permits the lowest ground relaypickup value for the primary feederbreaker. This type of winding configu-ration also eliminates any zerosequence current in the primary feederfor load unbalances in the secondary.

At higher primary voltages, 27 kVthrough 34.5 kV, some use hasbeen made of GROUNDED WYE-GROUNDED WYE windings. Theadvantage gained is the reduction of overvoltages which can result if oneleg of the unit is de-energized. Thedisadvantage is that the primarybreaker ground relay must be setmuch higher because load unbalancesand ground faults in the secondary arereflected by zero sequence currents inthe primary circuit.

3. Network ProtectorThe network protector can be in a non-

submersible housing, submersible orsuitable for mounting within a lowvoltage switchgear assembly. Both thetransformer side (line) and network(load) connections of the protector arebus bar which can accommodatetransformer flange connections andloadside connections to cable, buswayor switchgear buswork.

kVA Size Recommended Z

300 – 10001500 – 2500

5% or greater7% or greater

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17January 2003



Network protectors are special self-contained air power breaker unitshaving a full complement of current,potential and control transformers, aswell as relay functions to protect theintegrity of the low voltage networkbus. Normally, protectors do not haveany overcurrent protection in theforward direction; if necessary, the50/51 function can be achievedthrough the use of remote mountedprotective devices.

Figure 17.0-5 illustrates a simplifieddiagram of the various componentsof the network protector.

Note:The symbol for a protector is the airbreaker symbol with a dot in the middle.

Protectors have either rollout ordrawout mechanisms for easy mainte-nance. Protectors having the drawoutmechanisms, such as the Cutler-Hammer CMD type, are comparable toair power breakers in terms of mainte-nance and stored energy functions.The older rollout units utilize manuallydisconnected fuses and links whichmust be removed from the energizednetwork bus prior to rolling the unitout of the cubicle for inspection,testing and maintenance. Details onprotectors are reviewed later in thissection and the recommended spotnetwork equipment ratings for two,three and four unit configurations areshown in Tables 17.2-2 through 17.2-5 which appear on Pages 17.2-1 and17.2-2 in this product section.

The protector load side usually con-tains a network fuse, either meltingalloy or partial range current limitingtype. The fuses are present as back-upprotection if the protector fails to openproperly. These fuses are separatelyremovable, but do not drawout withthe protector mechanism. Commonly,the fuses are located at the top of eachprotector and this location is fixed.

The fact that the fuses are locatedon the network side means that fusemaintenance requires operators tocome into contact with live parts and

conductors which can deliver highfault currents. A method of easilydisconnecting the secondary of theprotector from the network bus,similar to the configuration of theprimary, is needed to isolate the fuseand protector.

4. Spot Network DisconnectsThe multiple sources of power to thenetwork bus can create a safety con-cern on the load side of each protector.Obviously, each protector loadside is

energized from the network so long asat least one transformer remains con-nected. The use of a network discon-nect can provide a degree of operatorsafety by requiring that the disconnectbe used to disconnect the protectorloadside from the network beforeallowing access to network fuses orprotector mechanism. Such a discon-nect reduces the likelihood of contact-ing live bus and forces operators tofollow a safe procedure prior to anyprotector maintenance. Accidentsinvolving protectors can be traced tothe absence of such devices incustomer’s facilities and distributionsystem designs. The Eaton’s Cutler-Hammer business encourages theuse of network disconnect devices,especially in facilities not having dedi-cated maintenance staff. Many formsof disconnect devices are available;the specific choice depends upon sev-eral related factors such as protectormounting, use of main breakers,protector type, etc. Three key choicesfor network disconnect devices areoutlined below.

Types of Network Disconnects

Principally, the three types are main airpower circuit breakers within switch-gear assemblies, incoming fuse trucksmounted within switchgear cells, andnon-loadbreak hookstick operatedswitches mounted above theprotectors in a NEMA 1 cabinet.

Regardless of the type used, each

disconnect is interlocked with theprotector to ensure that the loadbreakprotector is used to break and makethe load currents. The protectormechanism is rated for at least 10,000operations before maintenance and isthe best device to interrupt normalload currents. Protectors include anoperations counter to keep track of thenumber of operations. The interlocksmay be keyed type or electrical controlwiring. Refer to Figure 17.0-6 for atypical one-line.

Main Breakers

Main air power breakers are the most

expensive option to use as a networkdisconnect, however their interruptingrating guarantees proper operationunder all conditions including faultcurrents. Switchgear mounting of themain breakers means that the discon-nect device is the same type of deviceas all other overcurrent devicesmounted in the assembly, therebyrequiring common maintenance andoperation procedures. The mains areusually key interlocked with theirrespective protectors to ensure that

the protectors are opened first, thenthe mains are opened and rackedto a disconnect position prior tomaintenance of the protector orcircuit devices.

Main breakers include overcurrent trip

units to provide individual overloadprotection for each protector andconductors. This protection is not anormal function of the network relaysand augments protection generallyso long as the trip unit settings areproperly coordinated with the tie andfeeder devices. The trip unit protectiondoes not protect the incoming cableagainst fault currents such as groundfaults or short circuit currents; thesensors are not located at the linesideof the protector circuit, rather they areat the switchgear (load) side thusgiving only overload protection.

The key interlocking between main airpower breakers and network protec-tors may be eliminated since the mainis a true interrupting device usuallyrated at or above 65,000 amperesinterrupting at 480 volts. When mainsare used as loadbreak devices onnetwork services, the opening of amain may result in the opening of the respective protector, howevermaintenance procedures shouldalways verify device operation.

Fuse Trucks

Switchgear mounted fuse trucks are alsoa viable product for use as a networkdisconnect. They utilize truck mountedlimiters in a non-loadbreak cell. The costis lower than a main breaker yet the fusetype limiters provide a measure of faultprotection, but near the load end, not theline end of the protector circuit where thefuses are best located. The key interlocksare essential when using fuse trucks toassure that the protector is used as theloadbreak device. The fuse truck has noloadbreak rating, only a withstand rating.

The use of fuse trucks may allow theomission of the standard protectorfuses, since the fuse truck includesspecial breaker limiters. The limiters inthe fuse truck will be slightly faster

acting than the protector fuses. Thefaster fuse clearing may be a desirablecharacteristic, however limiter replace-ment is more costly than resetting a tiebreaker trip unit. The addition of thelimiters adds another device to coordi-nate, but may be the best solution forvery high kVA systems such as 8,000to 10,000 kVA nominal and wherevertical space does not exist at the topof the protector for a non-loadbreakerdisconnect as described on thenext page.

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Figure 17.0-5.Typical Network Protector Schematic Cutler-Hammer CMD Type

Figure 17.0-6.Partial Spot Network One-Line Diagramᕃ Recommended when no separate main breaker is used.

Non-Loadbreak Disconnect

The most popular network disconnectdevice for mounting above theprotector is the non-loadbreak boltedpressure switch. The device is hook-stick operated from the floor andprovides a very reliable means of visibly disconnecting the protectorcircuit from the loadside of the protec-tor. The switch is NEMA 1 cabinetmounted with double doors andelectrical interlocks to assure that theprotector is used to break the loadcurrent. The door interlocks havea defeatable procedure if qualifiedpersonnel need to gain access underload flow conditions. Key interlockingis not necessary.

This product has become a standardfor Eaton’s Cutler-Hammer businessand is manufactured in the same plantas the protector for improved mount-ing coordination. Recent designsmove the NPL fuses into the cabinet

to assure that fuses are not accessiblein another fashion. Space exists withinthe cabinet to mount separate currenttransformers to provide inputs forseparate instantaneous and timedelay overcurrent relays which protectthe protector circuitry from point of supply to the switchgear buswork. TheGeneral Services Administration usesthis type of product on hundreds of network units throughout the NationalCapital Region and in other areas of the country where networks are used.

Potential Transformer (PTs)

PTs

Protector Fuses

Loadside(Network)

NetworkProtector

Lineside(Transformer)

MPCV =ProtectorNetworkRelay

Transformer Control Txs.

480V 125V

208Vb

a

MPCV

Trip

MPCV Close

Ground

MPCV PhasingVoltage

Motor

Trip

MPCV Trip

MPCVVoltage

5 kV or 15 kVPrimary

208 or 480 WyeSecondary

NetworkTransformer

NetworkProtector

Fuses

Disconnect Switch

Main Breaker(Optional)

NC

50/5186

Tie Cont.Cont.

LV SWGR

3 Cts

The non-loadbreak design has beenchosen over the loadbreak for severalreasons. First, the loadbreak mecha-nisms need regular maintenance andshould not be allowed to sit in a closedposition for years, then be called uponto operate without failure. This type of duty is exactly what is required of anetwork disconnect. Additionally, theoperating mechanism of a loadbreakdesign requires a lot of force, morethan an operator can safely deliverfrom a ladder or step. Hookstick opera-tion from the floor is a safer proce-dure. Refer to Figure 17.0-7 for typicalsection view of network units using anetwork disconnect atop the protector.

Network transformer neutrals arebrought to the loadside area of thedisconnect for transitioning to theprotector circuit neutral for deliveryinto the switchgear. The loadside of

the disconnect can accommodateoutgoing busway or cables as needed.

50/51 Relaying for Protectors

Users who specify the non-loadbreakdisconnect can easily add the currenttransformers for relaying at the loadside of the protector circuits andprovide superior fault and overloadprotection for the incoming conduc-tors between the protector and theswitchgear buswork. The relays areusually mounted within the switchgearand utilize a lockout feature to trip andlockout the protector. Modern micro-processor relays such as the Cutler-

Hammer Digitrip

3000 can alsobe used for the 50/51 protection tosave costs and mounting space.

The use of forward relaying on theprotector circuit needs to be coordi-nated with the tie breakers to ensurethat the protector auxiliary 50/51protective settings are not faster thanthe tie settings. Coordination isachieved when the ties are faster act-ing than the 50/51 protector forwardovercurrent relays, and they usuallytrip open first due to the presence of multiple transformer faults passingthrough the ties. See Figures 17.0-14 and 17.0-15 for more details. Also referto Tables 17.2-2 through 17.2-5 fordetails on the recommended tie deviceratings and settings.

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17January 2003



System Neutral Grounding

Regardless of the device selected as thenetwork disconnect, the XO transformerneutrals are not grounded at the trans-formers. Rather they are brought intothe switchgear and grounded at one

and only one location. This configura-tion allows the use of the ground returnmethod of ground fault protectionwhose zone of protection extends fromthe secondary transformer windings tothe outgoing air power breakers in theswitchgear. Other ground fault detectionmethods are possible, but are consider-ably more complicated to wire andmaintain and are without significantadvantage or greater reliability.

5. Low Voltage DrawoutSwitchgear Configurations

The most reliable and safe networkbus equipment is in the form of lowvoltage drawout switchgear built perANSI C37 standards. Unlike the UL 891 switchboard assemblies, low volt-age switchgear utilizes true 200,000ampere braced buswork, drawoutstored energy air power circuitbreakers rated for 100% application,for easier maintenance — all of whichprovides superior performance com-pared to fixed mounted molded casebreakers in switchboard construction.This is true regardless of where theprotector is mounted. A typical switch-gear installation of a protector uses alow voltage switchgear compartmentwhich is 96 inches (2438.4 mm) high x50 inches (1270.0 mm) wide x 66 – 84inches (1676.4 – 2133.6 mm) deep. Theuse of transition sections between theprotector and switchgear ensures thatsufficient space exists to route bus-work between the two compartments.

Refer to Figures 17.0-8 through 17.0-12 which illustrate typical plan viewsand front elevations for double-endednetwork substations and threetransformer spot network designs.Figure 17.0-8 shows the bus configura-tion of the two-unit spot networksubstation. Note that there must be aseparate ground return neutral bus

which has only one point of connec-tion to the grounding conductor. Thistype arrangement permits selectivetripping of the Tie, then the protector.For a line-to-ground fault on Bus #1,the 86T lockout relay controlling theTie breaker will be operated first whenGFR-T detects 1.0 per unit groundcurrent. After the Tie breaker is open,the line-to-ground fault current issensed only by GFR-1, which willactuate the 86-1 lockout to trip thenetwork protector NP #1.

Figure 17.0-7.Typical Non-Loadbreak Network Disconnect Mounting Arrangement

For primary faults, the network relaymust be set such that it can respondto both reverse magnetizing levelsof current as well as to any primarycircuit fault current. Since mostsystems employ DELTA-WYE wind-ings, primary faults will not bedetected by either GFR-T or the GFRdevices associated with the protectors,since no zero sequence current willflow. However, if GROUNDED WYE-GROUNDED WYE transformers areused, the relay coordination must besuch that the network relay respondsfirst to primary feeder faults. This

permits the correct operation of theprotector under such conditions, sincethe GFR-T should not attempt to tripthe Tie open. Therefore, power willbe maintained on the low voltage buswith the Tie breaker remaining closed.See Figures 17.0-9 and 17.0-11 forlayout arrangements for dry-type andliquid-type spot networks respectively.

Figure 17.0-10 shows the bus configu-ration for a three-unit commercial spotnetwork. Again, the ground returnneutral bus is required which has onlyone point of connection to the ground-ing conductor. Selective tripping isachieved in the same fashion as the

double-ended network substation withGFR-T sensing ground current andoperating the 86T device which thenopens both Tie breakers. The groundrelays GFR-1, GFR-2 and GFR-3 willonly sense ground current after the Tie86 lockout is energized and the Tiebreakers are open. Interlocking auxil-iary contacts on the 86-T with the GFRcircuits guarantees this selective trip-ping and ensures the user that groundcurrents are accurately measured. Theampacity of the ground return neutral

bus must meet the minimum require-ments of the neutral bus. It is prudentto size the ground return neutral busthe same size as the phase bus, sincethe ground and neutral carry faultcurrents during abnormal events.

The space required by the groundsensors and connecting buswork canbe accommodated easily in two-unitspot networks. However, on three-and four-unit systems, the extensivestructure-to-structure insulatedground bus plus the normal phase,neutral and ground buses can reducethe usage of four breaker cells in theswitchgear to three. Usually, the low-est cell position must be blank dueto the rear mounting location of theinsulated ground bus. Vendor designsvary on this issue. All four breakercells are available on two-unit, three-unit, and four-unit systems fromthe Eaton’s Cutler-Hammer business,when DSII Switchgear is used.

The ampacity of the phase and neutralbuswork must meet the gross demandplus spare capacity for growth asstipulated by the National ElectricalCode for the loads served. If eachtransformer on a two-unit spot

network has been sized with 100%redundancy, then each protectorand load buswork should be rated tocarry the entire load from one primaryfeeder and one transformer. Three-unitspot networks can reduce the redun-dancy to 50% for the same loads sincetwo units remain in service. Four-unitspot networks may reduce the redun-dancy to 33%, unless the loads need tobe served from two remaining servicesin which case 100% redundancy isstill required.

Load Transition

Non-loadbreakDisconnectNEMA 1 Cabinet

Fuse Location(Inside)

Network Protector(CMD Type)

Section View

NetworkTransformer

Neutral(XO Bushingon Back)

PrimarySwitch

Neutral Bus

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Figure 17.0-8.One-Line for Two-Unit Spot Network

Figure 17.0-9.Front View of Double-Ended Network Substation

6. Typical Spot Network LayoutsThe amount of space available for theelectric service will dictate the size andquantity of the network units chosenfor a project. Double-ended substa-

tions, especially dry-type designs, tendto be arranged in a single lineup withthe primary feeders located at oppositeends of the room. Refer to Figure 17.0-9 for an example of this type of arrange-ment. The single lineup can be used if space permits. One alternative is tolocate the transformers behind, or infront of the switchgear, with intercon-necting busway or cables.

Three or more transformer unit spotnetworks cannot be arranged in onelineup, therefore they use the remotemounting of the transformers. Referto Figure 17.0-11 for an example of thistype of equipment layout. It is impor-tant to remember which side or endof equipment is used for normaloperations when designing a networklayout. The primary switches areoperated from the end as are the pro-tectors. Switchgear needs both NECclearances at the front and the rear, dueto the drawout breakers and the rearaccessible cable compartments. Payattention to the different voltage levelspresent, both medium and low voltage,and the required working clearancesgiven in the NEC or local codes.

N.P. #1 N.P. #2

86-1 86-2

50/51 50/51

PH. A,B,C PH. A,B,CNC

Tie

86-T

FeederBreakers

FeederBreakers

GFR-1

GFR-T

GFR-2

NN

GRN

(GroundReturnNeutral)

Loads Loads

Ground Bus

Transition

Sections

Transition

Sections

2 or 3PositionPRI SW.(Fuse)

Transformer NetworkProtector

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

FDR

Tie NetworkProtector

Transformer

2 or 3PositionPRI SW.(Fuse)

Equipment weights should also beinvestigated to ensure that the struc-ture can support the network assem-blies. Means of egress and routes toremove material if replacementbecomes necessary should beidentified. Avoid placing any networkequipment against any wall; the NECclearances required probably double if two means of egress are not available.Structural columns pose challenges,however they rarely defeat networkarrangements; watch for switchgeardoor openings bumping againstcolumns before they are fully opened.

The highest piece of equipment maybe the low voltage switchgear, whichis usually 96 inches (2438.4 mm) inheight, plus the 12 –14 inches (304.8 –355.6 mm) required by a rail mountedtop of gear breaker lifter device, or thenetwork disconnect, and must be

accommodated. Liquid transformerunits have very high core and coiluntanking heights, which precludesany chance of untanking the coreand coils in a normal building. SeeFigures 17.3-1 through 17.3-3.

Regarding conductors, it is prudent toremember that busway can enter orexit a switchgear structure only once.Room does not exist to accommodatemore than one run of busway in a sin-gle section, unless one connects at thetop and one connects at the bottom.

A typical plan view for a three-unit spotnetwork is shown in Figure 17.0-11;

four-unit spot networks are similarlydesigned. If it becomes necessary tosplit the switchgear assembly, positionthe splits at one side or the other of theTie devices. This approach simplifiesthe power connections of the neutraland ground buses.

7. Use of Current Limiting Fuses

Generally, this issue needs to beaddressed in the design stage of aproject, prior to specification writing.The expected fault currents need to becalculated for several locations, includ-ing secondary windings of transform-

ers, network switchgear bus (both sidesof Tie breakers), and at the load sideof feeder breakers. Network systemswhich utilize 800 ampere framebreakers and deliver more than 65,000amperes of fault current should usefused feeder breakers such as Eaton’sCutler-Hammer DSLII type, or Mag-numDS breakers rated up to 100,000amperes. The same applies to 1600and 2000 ampere frame devices.

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Figure 17.0-10.One-Line for Three-Unit Spot Network

Figure 17.0-11.Floor Plan for Three-Unit Spot Network System

Network protectors are normallyequipped with load side fuses (eithermelting alloy or partial range currentlimiting silver sand) and serve asbackup protection should the protector

fail to open on reverse fault currentconditions. Tie breakers are availablewith 65,000 and 85,000 ampere inter-rupting ratings and only need to befused if N-1 transformers can deliverhigher fault currents (where N equalsthe number of transformers used ina spot network). Feeder breakers areavailable with 35,000, 50,000 and65,000 AIC ratings and require fusesif the total fault current from all (N)network transformers is greater than

the available ratings. When fuses areused on air power breakers, theratings increase to 200,000 amperes.

In two transformer spot networks, onecan argue that neither the protector

nor the Tie needs to be fused for anyapplication up to and including 2500kVA transformers. The principal logicis that the Tie can experience only thefault current from one transformer andthat the Tie protective trip settings pro-vide faster acting backup protectionthan the protector fuses for reversepower conditions. Usually the fusesremain as part of the protector packageas backup protection.

N.P. #1 N.P. #2

86-1 86-2

50/51 50/51

PH. A,B,C PH. A,B,CNC

Tie

86-T

FeederBreakers

GFR-1

GFR-T

GFR-2

NN

Loads Loads

Ground Bus

NC

Tie

Loads

FeederBreakers

GRN(Ground Return Neutral)

86-3

50/51

PH. A,B,C

N

GFR-3

N.P. #3

N

FeederBreakers

FDRSAux.Sections Tie FDRS Tie FDRS

Primary Switch

NetworkTransformer

Network Protector

Busway or Cable

Low VoltageDrawoutSwitchgear

Aux.Sections

Aux.Sections

Unlike silver sand fuses, melting alloyfuses cause a lot of metal fragmentsto contaminate the protector housingand mechanism. Although popularwith utilities who have maintenancestaff to clean protectors, the more

modern type of silver sand fuseprovides cleaner arc interruption.Switchgear breakers always use themore modern type of fuse.

8. Network Device CoordinationBy way of example, we shall illustratethe level of coordination possible in atypical two-unit network system asshown in Figure 17.0-13. In this exam-ple, two networkable primary sourcesare available and several transformersare presumed to be fed from each of the two primary circuits. The upstreamprimary device is a 13.8 kV vacuumcircuit breaker with a complement

of relaying.

The medium voltage switches areCutler-Hammer fused air type. Theswitches have two positions, openand closed, not three positions. Werecommend that the primary switchesuse key interlocks with protectorsto ensure that the protectors areused to break and make load currents,although this interlocking is notabsolutely necessary since the switchesare loadbreak rated. The lack of a groundposition in the primary switches doesnot impede the normal operationof the network system; rather itmakes grounding the primary cablea manual procedure.

In this example, a two-unit networkwith 1000/1500 kVA dry transformersAA/FA, 80°C rise are utilized. Thetransformers are configured DELTA-WYE with 13.8 kV primary, a 480 voltwye secondary, and the impedanceof each is within the range of 5.75to 7.00%. The Eaton’s Cutler-HammerType CMD Network Protectors arerated 1875 amperes and are mountedwithin low voltage switchgearstructures. The CMD is a deadfront,drawout protector whose operationis very similar to the type DS air power

circuit breaker used throughout theswitchgear to distribute power to theoutgoing circuits. The network relayused within the CMD is the MPCV-Dtype, a microprocessor-integratedsolid-state relay which allows for fieldprogramming the network characteris-tics. All CMD protectors are factorywired for application of remote tripand lockout functions, which will beutilized in our example via the 86lockout relay and separate 50/51protective relay.

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Discussion


Figure 17.0-12.Floor Plan for Double-Ended Network Substation

Figure 17.0-13.Example of Two-Unit Spot Network Coordination Issues

The 50/51 relay will use 2000/5 ratiocurrent transformer inputs fromcurrent transformers mounted on theload side of each protector within atransition box. The 50/51 device canbe multiple phase electromechanicalrelays, however we have chosen anewer type of solid-state relay, Digitrip3000, due to its broad range of fieldprogrammable settings. Thus, theprotectors are used as main over-current protective devices as well

as protectors. When transformers areremote from the switchgear, thecurrent transformers must be locatedwithin a transition box atop the protec-tors. The current transformers may beused for metering also, or if moreaccurate metering at lower currentlevels is desired then a second set maybe necessary in the switchgear withmulti-ratios to match the averageload demands.

Aux.

Sections FDRS Tie FDRS

Network

Transf ormer

Network

Protector

Busway or

Cable Tray

Low VoltageDrawout

Switchgear

Network

ProtectorNetwork

Transf ormer

Aux.

Sections

Primary MediumVoltage Devices

#1

Two PositionFusible Primary

Switch

1000/1500 kVADry Transformer

#2

AA/FA

1875A CMDNon-Fused Protector

2000A

Tie

NC

50/51

Typical DS or DSL Feeders

To OtherSpotNetworks

65ECLE Fuse

50/51

The low voltage assembly usesEaton’s Cutler-Hammer DSII breakersfor both Tie and Feeder devices. TheTie breaker will be a DSII-620, 2000Aframe, 1600A trip, electrically oper-ated, drawout design, incorporatingthe Digitrip 510 trip unit. The feederbreakers are a mix of DSII-308, 800Aframe, and DSII-516, 1600A frame toserve the outgoing feeder circuits.The switchgear will panel mount thetwo 50/51 relays which provide over-current protection for the protectors.

General Discussion — Coordination Curves

The protective device settings for atwo-unit spot network are similar tothose used for a standard double-ended substation. The goal is to serveboth continuity of service and protec-tion equally. Settings should not favoreither one or the other, but rathershould keep loads served if at all

possible and minimize nuisanceoutages even under serve faultconditions, including ground faultevents. Basically, settings should beimplemented which allow the closestupstream device near a fault to clearbefore other upstream devices trip.Faults in a network have more thanone source, which is a major differ-ence compared to double-endedsubstations with a normally openTie breaker.

In Figure 17.0-14, we plot the time-current curves of the medium voltagepower fuses, whose main function is

to provide short circuit protection toeach transformer, the ANSI damagecurve typical for the transformers, the50/51 relaying upstream from eachspot network, the Tie and Feederdevice trip curves, and the 50/51 relay-ing used by each protector. We haveshown the primary 50/51 protectiverelaying curves by postulating theirrelative position as being to the rightof each damage curve and to the left of primary cable damage curves, sinceseveral transformers are served byeach primary service. In other words,several vault locations exist in thefacility. Obviously, these primary

relays cannot protect each transformerindividually, nor is it desirable to doso since it is better to isolate a simplefaulted transformer with a power fusethan to open the entire primary circuit.

The following paragraphs detail theprotective device settings, discuss thecurves, and review the important issues.

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ANSI Transformer Damage Curves

Two curves are plotted: both the 100%and the 58% damage curves areshown for the dry types in ourexample. These curves are defined inANSI Standard 141. The 58% curve

reflects the fact that a one per unitsecondary fault on a GROUNDED WYEtransformer creates a 0.58 per unitfault in the primary conductors whenthe primary windings have a deltaconfiguration. The curves illustratetime-current restrictions for unitsexperiencing more than 10 faults ina lifetime.

Eaton’s Cutler-Hammer CLE 65EPower Fuses

The selected current limiting fuse, 65E,provides little if any overload protec-tion for the transformer, however, itdoes an acceptable job of supplying

NEC code mandated short circuitprotection for the 100% damage curve.The fuse cannot provide protectionfor the 58% curve and downsizing theselected rating lower than 65E is likelyto result in nuisance fuse operation.Each power fuse vendor has applica-tion tables and charts to properlyselect fuses for any application.

The fuse meets the NEC stipulatedprotection, but lacks the flexibilityof a relay with nearly continuousadjustments. If superior protection isdesired, then a vacuum breaker with50/51 relaying should be used in lieuof the fused primary switch. Do not

use 50/51 relaying on a load inter-rupter switch.

Figure 17.0-14.Two-Transformer Spot Network Phase Overcurrent

Legend:

R Primary 50/51 Relaying - Typical for These Transformers

T3 100% ANSI Damage/Withstand Curve for Transformer

T1 58% ANSI Damage/Withstand Curve

F Power Fuse 65E Rating

P Network Protector Relay 50/51 - (Both LTD = 40 Seconds and 6 Seconds Shown)

T Tie Breaker DSII-620 1600AT MAG = 1 TX INRUSH

B Feeder Breaker DSII-308 800AT 3MAG = 3 TX INRUSH

CURRENT (Amperes)

100

T I M E

0.1

1.0

10

100

1000

0.01

1000 10000 100000

T3

MAG

3MAG

T1

B

T

PF

T3

R

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Protector Relaying — Eaton’s Cutler-Hammer Digitrip 3000 Plus Ground FaultRelay (GFR)

Network protectors do not have anyform of forward 50/51 (instantaneousand time overcurrent) protection,

therefore if it is desired it must beadded separately. An 86 lockout relayis recommended for positive lockoutindication and reset operations. Thecurve for the Digitrip 3000 is shown inFigure 17.0-14 and depicts the settingsfor this microprocessor-based solid-state multi-phase relay. Using the2000/5 ratio current transformers, thesettings are as follows:

Long Time Pickup(LTPU) = 1.0 (2000A)Long Time Delay I2t(LTD) = 40 secondsShort Time Pickup(STPU) = 3 X (6000A)Short Time Delay(STD) = 0.3 secondsInstantaneous(INST) = 11 X (22000A)Ground Fault Relay(GFR) = 700A pickupGround Fault Relay(GFR) = 0.58 seconds

(35 cycles)

It is very important that the protector50/51 settings be slower than the Tiebreaker. The faster acting Tie is desiredfor isolation of switchgear faultsbetween one side of the Tie and theloadside of a protector without taking

the whole network down. The Tieclears one transformer’s fault contribu-tion, while the unfaulted side remainsenergized. The protector experiencingthe remaining fault current will subse-quently trip open, thereby isolatingone-half of the network bus for repair.

Faults located in the transformersecondary windings may open boththe Tie and the protector, dependingupon the magnitude of the event.The protector should open first uponreverse power, since protectorsrespond to reverse power in 7 cycles.If the Tie also trips open, the Tie can be

reclosed to serve the entire load againafter locking out the protector on thefaulted transformer.

Note:The transformer is given superioroverload protection by the Digitrip 3000compared to the level of protection givenby the power fuse. This is especially trueeven in the overload region of the ANSIdamage curve.

Tie Breaker — Cutler-Hammer DSII

with Digitrip LS Plus Ground Fault Relay

The settings shown in Figure 17.0-14 were developed using 2000/5 sensorson the Tie breaker. The settings recom-mended are:

Long Time Pickup(LTPU) = 0.8 (1600A)Long Time Delay I2t(LTD) = 2 secondsShort Time Pickup(STPU) = 3 X (4800A)Short Time Delay(STD) = 0.2 secondsInstantaneous(INST) = Not usedGround Fault Relay(GFR) = 700A pickupGround Fault Relay(GFR) = 0.58 seconds

(35 cycles)SeeFigure 17.0-15

These settings allow the Tie to actquickly for abnormal current condi-tions, yet also provide enough delayto allow protectors to trip on reversecurrent when protector operation isthe prudent first course of action. Also,larger feeder devices, such as 1200-ampere DSII-516 breakers (not shownin Figure 17.0-14) will easily fit to theleft and beneath the Tie curve. It isimportant to set the Tie to operatequicker than the protector 50/51 relay-ing. The faster Tie settings assure thatswitchgear bus faults do not take the

entire service down (only half). In ourexample, the Tie will only be calledupon to interrupt the fault current fromone transformer.

Typical Feeder — Cutler-Hammer DSII-308with Digitrip LIG

The settings in Figure 17.0-14 weregenerated using 800/5 sensors appliedon the feeder breakers. The Digitrip510 trip unit settings are:

Long Time Pickup(LTPU) = 1.0 (800A)Long Time Delay(LTD) = 2 secondsShort Time Pickup(STPU) = Not usedShort Time Delay(STD) = Not usedInstantaneous(INST) = 2 X (1600A)Ground Fault Pickup(GFPU) = F (500A)Ground Fault Delay(GFD) = 0.3 seconds

(18 cycles)SeeFigure 17.0-15

These settings provide for fast actionof feeder devices experiencing themaximum fault duty of the switchgear(fault current from two transformers).Ground fault protection is recom-mended for the feeder trip units; thesesettings can be coordinated with thetwo-stage ground fault detectionsystem (single point ground returnmethod) mentioned earlier inFigure 17.0-8. Suggested ground faultprotective device settings are illus-trated in Figure 17.0-15, and the set-tings are listed under the protector, Tie

breaker, and feeder device discussionin this section.

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Ground fault settings are establishedessentially the same as a double-ended substation using a single teeground point and ground return meth-odology. The Eaton’s Cutler-HammerDSII feeder breakers are set to coordi-nate with downstream devices so thatdownstream breakers experiencinga fault trip first. The GFR relays forthe Tie and protectors are set slightlyhigher in pickup and have a longerdelay than the ground fault for thefeeder devices. Protector and Tieground fault settings are usuallyset at the same levels; coordinationis achieved by interlocking the twostages so that the Tie stage operatesfirst followed by the protector stage.Ground current originating from faultsin the switchgear buswork or incomingconductors is directly measured by theGFR on the Tie, then by one of theprotectors after the Tie opens. Subse-quently, the GFR on the faulted zonecauses the protector experiencing thefault to trip open thereby isolating thefault completely. Downstream groundfaults are cleared by downstreamcircuit breakers or the DS feederbreaker serving the faulted circuit.

Figure 17.0-15.Spot Network Ground Fault Protection

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Ref. No. 0468

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17January 2003

Spot Network EquipmentNetwork Protector Equipment

CMD Network ProtectorRef. No. 0469

Advantages

Exclusive Drawout Design: Withpositive safety interlocks, providesmaximum protection against contactwith energized components while

disconnecting the unit for test or main-tenance; ensures maximum safety foroperating personnel. All main currentcarrying and mechanical operatingcomponents are located behind a“deadfront” steel panel that minimizesthe possibility of tools or hands frombeing inserted into an energized protec-tor. The drawout unit is operated by ahand-cranked levering system, whichcannot be engaged unless the circuitbreaker is open and cannot be disen-gaged unless the drawout unit is eitherfully disconnected or fully connected.

Modular Construction: Simplifies fieldmaintenance and/or replacement of

components of drawout unit. Thenetwork protector can be quickly putback in service, reducing maintenancetime to a minimum.

Spring-Close Operating Mechanism:Avoids partial closures. The CMDSpring-Close mechanism will notpermit closing motion of the contactsto start until the closing springs arefully charged.

Externally-Mounted Silver-Sand Fuses:Operate with no contamination of the protector, and will positivelyinterrupt fault current to disconnectthe protector from the network busin abnormal situations.

Capacitor Trip Device: Providesconsistent tripping action whichworks independent of the systemvoltage. Used with the capacitor tripactuator (CTA), the network breakercan be remotely tripped withoutsystem voltage being applied.

CMD Protector Features

Design Features

ᕃ Submersible enclosure.

ᕄ Extension rails.

ᕅ Drawout unit.

ᕆ Operation counter.

ᕇ OPEN-CLOSED breaker positionindicator.

ᕈManual trip button.

ᕉ Control module withdrawnor inspection.

ᕊ JC contact.

ᕋ JA contact.

ቫ Actuator for JA and JC contacts. Withdrawout unit in “connected” position(fully inserted into enclosure) anddoor closed, the external operatinghandle in AUTO position depressesthe JA contact to put the networkprotection under the control of therelays. The JC contact is depressedwhen the external operating handleis moved to the CLOSE positionto electrically close the protector(external handle is spring returnedfrom CLOSE to AUTO position).

ቭWhen external operating handleis moved to the TRIP position, thislinkage expands to mechanically

operate the trip button on the frontof the network protector.

ቮWindow to view operation counterand OPEN-CLOSED indicator.

ቯ Tubular door gasket.

ተ Test valve.

ቱ Shutter over levering shaft.

ቲ Disconnect finger clusters.

ታ Silver-sand, non-display NPL fuselocated within water-tight housing.

ቴ Epoxy housing to enclose the

NPL fuse and also serve as stand-off insulator for the network sideterminal. Various spade configura-tions or threaded stud adapters areavailable for mounting on the top of this epoxy housing.

ተቴ

ታ

ቲ

ቢባቤ

ቭ

ቮ

ብ

ቱ

ቨ

ቯ

ቫ

ቧ

ቦቪ

ቩ

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Design Features (Continued)

The Eaton’s Cutler-Hammer CMD isdesigned to improve the safety andreliability of network protectors onboth spot networks and distributed

grids. With present rollout type net-work protectors, removing the rolloutunit from service involves unboltingenergized network fuses and discon-nect links. The Cutler-Hammer CMDeliminates these operations.

Drawout Mechanism

Gaining Access to Levering Shaft

The unique drawout design of the CMD makes it unnecessary for

personnel to come into contact withenergized parts when connecting ordisconnecting the protector drawoutunit. Special insulated tools or rubbergloves are not required to operatethe drawout mechanism. With thedrawout design, the front of the unitis covered by a protective steel barrierthat cannot be removed until the draw-out unit is levered-out. To gain accessto the levering shaft, the manual tripbutton must be depressed and theshutter over the levering shaft must beraised to insert a special crank. Thecrank is held captive by the shutteruntil the drawout is fully disengaged.

The protector breaker is held trip-freeuntil the crank is removed, therebyoffering the maximum degree of safety. The drawout finger clustersremain on the drawout unit when it isremoved from the protector enclosure.

In addition to its safety advantages,the drawout design saves maintenancetime. The CMD can be placed in or takenout of service in one-third of the timerequired by present rollout designs.

Inserting Crank

Cranking to Drawout

Spring-Close Mechanism

In the CMD Network Protector, theclosing motor charges tension springs,the contact closing is controlled by atoggle-cam mechanism, which will notallow closure to begin until the springscontain sufficient energy to close andlatch the contacts onto 25,000 amperesrms symmetrical for an 1875A, CMD,40,000 amperes rms for a 3000A CMD

at 480 volts.With the CMD spring-close mecha-nism, the contact closing speed isindependent of the speed of thespring-charging motor. The contactseither close and latch positively, orthey do not attempt to close at all.

For test purposes, the operating mech-anism can also be charged manuallyto close the protector.

Modular Construction

CMD Drawout Unit

The CMD drawout unit can beremoved from its enclosure andreturned to the service shop as a unit.It is equipped with lifting eyes and isdesigned to be freestanding to facili-tate storage and handling. Also, thethree main components of the draw-out unit — the pole unit module, theoperating mechanism module, and

the control module — are easilyremovable for replacement or repair.

The pole unit module, in the uppersection of the drawout unit, containsthree identical pole unit assemblies,each containing a contact system,arc interrupter, primary disconnect,current transformer and supportinginsulation. For maximum reliability of the unit, all phase-to-phase and phase-to-ground spacings of the power busare 1-1/2 inches (38.1 mm) minimum.

The operating mechanism module,located in the middle section of thedrawout unit, consists of an operating

linkage and its tension springs, theclosing motor (which charges thetension springs), and the capacitortrip actuator. The mechanism moduleis removable from the drawout unitas a complete assembly afterdisconnecting three push rodsand mounting hardware.

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17January 2003



The control module is a slide-outassembly which can be removedfrom the drawout unit only when thedrawout unit is withdrawn from thehousing. It contains the motor auxil-iary relay, auxiliary switches, phasing

resistors, network relays, control andpotential transformers for 480 voltoperation, and the bulk of the controlwiring. Complete removal permitsinterchangeability with a sparemodule for servicing on the site orin the repair shop.

Externally-MountedSilver-Sand Fuses

NPL Fuse

The Eaton’s Cutler-Hammer NPL fuseprovides backup protection againstpossible relay or breaker malfunctionfor faults on the primary feeder. Thisnonexpulsion silver-sand fuse, designedfor use with the CMD Network Protectorexclusively, matches the transformersafe-heating characteristics.

The fuses mount on top of the protector

enclosure, in leaktight molded epoxyhousings which serve as stand-off insulators and terminal mounts.Locating the fuses outside the protectorenclosure provides positive isolatedfault interruption to assure the protec-tion of the network bus. In the unlikelyevent of an internal fault in the protec-tor or at the secondary bushings of the transformer, the fuse will operatereliably to remove the unit from thenetwork bus.

With the Cutler-Hammer CMD and itsNPL fuses there is no need for users tomount separate current-limiting fusesbetween the network protector and thenetwork collector bus. Elimination of these separate fuses results in a sub-stantial cost saving to the customer.

Although the external fuse housingsisolate the fuses from the protectorenclosure, a small vent hole betweeneach fuse housing and the protectorenclosure make it possible to pressure-test the enclosure and housings as atotal assembly.

Capacitor Trip Actuator

Located in the mechanism module,the Cutler-Hammer Capacitor TripActuator (CTA) produces a mechanicalforce to trip the breaker once the trip-ping circuit has been completed andthe MPCV relay calls for a trip. The CTAis a solenoid actuator which usesa compression spring as its resetmechanism. A capacitor is chargedthrough a diode, and is used to storethe required tripping energy. When theMPCV relay calls for a trip, the capaci-tor discharges through the closedrelay trip contact and energizes theCTA, which in turn trips the breakermain contacts. Without power beingsupplied to the transformer side of the network protector, the capacitorstores enough energy to attempt fourelectrical trips before the capacitorrequires to be recharged.

Figure 17.1-1.Capacitor Trip Actuator

External Operating Handle

Operating Handle

An external handle mounted on theenclosure door makes it possible toopen or close the protector withoutopening the enclosure. The handlehas three positions: OPEN, AUTOand CLOSE.

When moved to the OPEN position,the handle trips the protector mechani-cally. The handle can be padlocked inthe OPEN position.To Trip

Reset Spring

Trip Coil

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When moved to the AUTO position,the handle operates an internal switchthat places the protector under thecontrol of the network relays. Thehandle can be padlocked in theAUTO position.

When moved to the CLOSE position,the handle operates an adjacent switchthat closes the protector electrically.A spring returns the handle from theCLOSE position to the AUTO position,to return the protector to the controlof the relays. The handle cannot belocked in the CLOSE position.

Anti-Close Device

The CMD Anti-Close Device preventsthe protector from closing, eitherelectrically or manually, if the tripcontact of the MPCV relay is closed.An auxiliary shunt trip, energizedwhen the breaker is open and themaster relay is calling for trip, opensthe motor-closing circuit and holdsthe operating mechanism in thetrip-free position. Thus, the protectorcannot inadvertently be closed intoan unsafe condition.

Barrier Insulation System

Insulation System

The individual pole unit assemblies inthe upper module are separated by redglass-polyester barriers extending

from the front to the back of the enclo-sure. These barriers reduce personnelexposure during maintenance andprovide additional reliability when theprotector is in service.

Reduced Current Path

Figure 17.1-2.Current Path

The reduced and simplified currentpath through the CMD minimizespower losses and the possibility of

faults on the bus. In transformer-mounted protectors (illustrated), thepower bus is confined to the uppersection of the protector, providing aminimum current loop and increasingpersonnel safety.

Teflon Insulated Control Wiring Harness

Wiring Harness

The Eaton’s Cutler-Hammer CMDemploys harness wiring, simplifyingany rewiring that might becomenecessary throughout the life of theprotector. The Teflon-insulated cableis rated 1000 volts and 200°C; thisextra electrical and thermal marginprovides long control wiring life.

Control Module DetailsThe control module tray can be with-drawn from the drawout unit for inspec-tion. Until the module is returned to itsnormal position, the protector breaker

is held trip-free. Control modules for useat 480Y/277 volts will be supplied withthe necessary control and potentialtransformers to utilize 216 volt relays.The modules are electrically connectedto the protector mechanism throughpolarized plugs. For 216Y/125 volt pro-tectors the control modules are suppliedwith interference plugs to prevent themfrom being connected to a 480Y/277 voltprotector. All protectors will be factorywired with provisions for use with aremote trip and lockout scheme.

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17January 2003



NPL Fuse

NPL Fuse

Eaton’s Cutler-Hammer NPL fusehas been designed as a nonexpulsion,silver-sand type fuse. It is exclusivelyfor use on the CMD network protector.Each end terminal is fabricated fromhigh conductivity, impact extrudedcopper. High quality NEMA Grade G5convolutely wound glass melaminetubing is permanently sealed to theterminal with RTV Silastic to elimi-nate possible sand leakage or mois-ture entry. The terminals and tube aresecured together with stainless steel,high strength, spirally wound pins.All fuses are tested on an ultra-lowresistance measuring instrumentcapable of resolving one-hundredthof a micro-ohm and evaluated on

the basis of statistical probabilitytechniques to ensure uniformity.

Characteristics of the NPL fuse havebeen especially tailored for coordina-tion with the transformer safe-heatingcurve and in consideration of theprotector interrupting rating. Thisspecially designed characteristic curveis less inverse than the ordinarymelting characteristic of a silver-sandfuse. The curve is a function of thedesign of the unique, silver elementused in its make-up.

The NPL fuse does not become current-limiting within the interrupting ratingof the protector. The fuses have beensuccessfully tested in its epoxy enclo-sure at a 3-phase fault condition of 150,000 amperes at 600 volts.

Figure 17.1-3.Average Melting Curve of NPL Fuse

Table 17.1-1.CMD Protector NPL Fuse Selection

CurveNumber

ProtectorCurrent Rating

Fuse StyleNumbers

Number of MountingHoles in Fuse

216 Volts

12345

800120018752500 – 28253000

140D318G04140D318G05140D318G01140D318G02140D318G06

44466

480 Volts

123

45

80012001875

2500 – 28253000

140D318G04140D318G05140D318G01

140D318G02140D318G06

444

66

1 2 3 5

1000

109

7

6

.9

4

5

.5

.3

.2

10090

30

20

500

300

200

1 0 , 0

0 0

8 0 0 0

6 0 0 0

9 0 0 0

7 0 0 0

5 0 0 0

4 0 0 0

3 0 0 0

2 0 0 0

1 0 0 0

8 0 0

6 0 0

9 0 0

7 0 0

5 0 0

4 0 0

3 0 0

2 0 0

1 0 0

8 0

60 9 0

7 0

50403020109875 6431 2.9.8.7.5 .6

600

900800700

400

40

8

50

80

60

70

3

1

2

.8

.7

.6

.4

.1.09.08.07

.06

.05

.04

.03

.02

.01

1 0 , 0

0 0

8 0 0 0

6 0 0 0

9 0 0 0

7 0 0 0

5 0 0 0

4 0 0 0

3 0 0 0

2 0 0 0

1 0 0 0

8 0 0

6 0 0

9 0 0

7 0 0

5 0 0

4 0 0

3 0 0

2 0 0

1 0 0

8 060 9 0

7 050403020109875 6431 2.9.8.7.5 .6

1000

109

7

6

.9

4

5

.5

.3

.2

10090

30

20

500

300

200

600

900800700

400

40

8

50

80

60

70

3

1

2

.8

.7

.6

.4

.1

.09

.08

.07

.06

.05

.04

.03

.02

.01

Scale x 1000 = Current in Amperes

S c a l e

x

1 0

=

S e c o n d s

4

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Choice of Enclosuresand MountingsEaton’s Cutler-Hammer CMD NetworkProtector is available with two typesof enclosures and in two mountingstyles. For use above ground, or invaults where no flooding occurs, aNEMA weatherproof enclosure isavailable. A waterproof, submersibleenclosure is available for use in vaults,subways and other locations suscepti-ble to flooding. Each type of enclosurecan be supplied for separate mountingor transformer throat mounting.

The mounting dimensions andterminal locations on the throat of the transformer mounted networkprotector shall match the dimensionsand terminal locations of the trans-formers as specified in ANSI/IEEEC57.12.40. Thus the transformer

mounted CMD network protectorwill fit with any appropriately sizednetwork transformer built to ANSI/ IEEE C57.12.40 standards.

Precharged Stored-EnergyMechanism for the Type CMDNetwork Protector

For fast reclosing of the Type CMDnetwork protector, we offer precharg-

ing of the stored energy mechanism.This mechanism charges its closingsprings only after the main contactscompletely open. It will then store thespring energy by holding the chargingsprings at a predetermined stoppingpoint in the spring charging cycle.

When the MPCV relay calls for a “close,”the closing circuit is completed througha closing coil which, via a latch, releasesthe spring energy and thereby closesthe network protector.

Once the springs are charged and therelay contacts have called for “close,”the complete network protector clos-

ing time is approximately 5 cycles.

This feature is most beneficial in theapplication of two unit, 480 volt, spotnetworks in which one network protec-tor may be “open” (due to light loads)and the other feeder, which suppliedthe load’s power requirement is now“opened.” The network protector,which was opened because of lightloading, is ready to “close” with itsclosing springs charged. This closingaction will take place in approximately5 cycles, and will eliminate motorstarter drop-out and reduce apparentlight “flicker.”

The standard CMD mechanism, whichtakes approximately 4.5 seconds tocharge and close the breaker contacts,is suitable in all low voltage distrib-uted grid systems as well as threeor more unit 480 volt spot networks.However, the stored energy mecha-nism can be applied in all typical

network services.

Note:Published fault close ratings of theCMD are significantly reduced in using thestored energy mechanism.

Submersible Enclosure for Transformer Mounting

1875A NEMA 1A Semi-Dust-Tight Enclosure for Transformer Mounting

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17January 2003


Type MPCV Network Protector RelayRef. No. 0475

Description

The microprocessor controlled networkrelays were designed to replace the typeCN-33 electromechanical master relay,the type CNJ electromechanical phasing

relay and the type BN electromechanicaldesensitizing relay. The MPCV seriesrelays use the same voltage and currentinputs as do the electromechanicalequivalent. They also continuallymonitor voltage across an open breakerand current through a closed breaker,and perform the following functions.

s The trip contact will close uponbalanced fault conditions if thepositive sequence power flow isout of the network.

s The close contact will close if theensuing positive sequence powerwill be into the network.

s

The trip contact will close upon theflow of reverse magnetizing currentof its associated transformer.

The MPCV series relay will mount onstandard existing CMD and CM-22network protectors utilizing thepresent system of low voltage relaymounting studs.

Warning

The MPCV relays are designed to beused on network protectors whichhave been wired for 216Y/125 voltor 480Y/277 volt service using relaypotential transformers. This relay is

designed to operate at 125 volts (lineto ground). Do not attempt to applythis relay on any other system voltageor configuration.

Figure 17.1-4.Trip Characteristics

Failure to follow these instructionscould result in severe personal injury,death, and/or product or propertydamage.

Functional Characteristics

All measurements in the relay aremade as net voltages and currents,computed as the positive sequencevoltage and current (represented asV1X or I1) and the negative sequencevoltage and current (represented asV2X or I2). The network positive andnegative voltages sequence aredenoted V1N and V2N respectively.The other important voltage is thephasing voltage, which is the differ-ence between the transformer andnetwork voltages, whose sequencecomponents are denoted V1P and V2P.

The V1N is defined as the referencephasor for all phase measurements,and the nominal phase-to-neutralvoltage (1 P.U.) is defined as 125V ACrms. From this, the basic functionalcharacteristics are graphically depictedin Figures 17.1-4 through 17.1-6.

Trip FunctionFigure 17.1-4 diagrams the current-induced trip characteristics. The posi-tive sequence current I1 is multipliedby the cosine of the angle of its phasorrelated to V1N. If the resulting sign isnegative, then reverse power-flow isindicated. The trip level (11COSØ) forthis can be adjusted from .05 to 5

percent of rated current. The cosinemultiplication operation results in thestraight line which is perpendicular tothe phasor.

In a different fault condition, thenegative sequence network voltageV2N will exceed 0.06 P.U., in whichcase the trip curve is rotated 60ºclockwise direction to the alternatetrip curve shown, with the same triplevel as set before (.05 to 5 percent).In either case, the trip is called for after50 mS, or three line cycles, in a 60 Hzsystem, of a fault condition.

The BN function can be initialized to

modify the characteristics and timingof the reverse-current trip conditions.This adds to the basic detectionrequirements that the true rms valueof the reverse current exceeds somesettable threshold between 50% and250% of the protector CT rating. Whenthe magnitude of the reverse current isless than the settable threshold, a tripwill occur if the condition exists foran adjustable time period of 0 to 5minutes. The BN function is standardon all MPCV relays.

Figure 17.1-5.Closing Characteristics —Straight Closing

Close CharacteristicsFigure 17.1-5 also diagrams the volt-age regions for close, float and tripoperation when the protector is open.Under extreme conditions when theprotector is open, a trip is called forto prevent a dangerous manual closeoperation. With the protector openand the network and transformer volt-ages normal and balanced, positivesequence phasing voltage (V1P) ismeasured. If V1P is in the close region,the relay makes its close contact. If V1P is not in the close region, but isless than 0.06 P.U., then the float is

called for, as this voltage difference isnot deemed dangerous regardless of the phase relationships, and manualclose of the protector would notexceed the breaker capacity. If V1P isgreater than 0.06 P.U. and does not liein the close region, then trip is calledfor to prevent manual closing. Therelay also calls for trip under all rolledand crossed phase conditions, evenwhen either the transformer side orthe network side of the protector isde-energized.

The close contact will close only inthe quadrant defined by the two lines,

termed master and phasing. The phas-ing line, emanating from 0, defines aminimum phase angle of the phasingvoltage ahead of the network voltagefor closing, which is selectable at +5º,-5º, -15º or -25º. The master line setsa minimum difference between thetransformer and network voltage, set-table from 0.0008 to 0.02 P.U. at 0º (inphase). This line exhibits a slope of 7.5º.

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Type MPCV Network Protector RelayRef. No. 0476

Figure 17.1-6.Circular Closing Curve

If the network side is de-energized,and the transformer side is energized,

the close contact will close, if V1N isless than 0.1 P.U., and V2N is less than0.06 P.U., and V1P exceeds 0.8 P.U.Note that, as stated before, if V2Pexceeds 0.2 P.U., then the trip contactwill close, indicating crossed phaseson either the transformer side or thenetwork side.

Note:If the phases are crossed on boththe transformer and the network side, V2Pcould be very close to or equal to zero, butthe trip contact will close as V1N is less than0.1 P.U. and V1P is less than 0.8 P.U.

The other closing curve characteristic

option available is the circular lineclosing curve which maintains thesame value of phasing volts fromthe -25° to +90° quadrants (refer toFigure 17.1-6). The circular closingcurve permits the network protectorto close at lower loads while assuringthe watt flow is into the network.

Any close conditions must exist for500 mS before the close contactwill close.

SettingsAll settings can be altered through adigital programming pendant which

plugs into the unit while mounted onthe network protector breaker. Whennot in use, the pendant may be storedseparate from any network protectorlocation, most conveniently with thenetwork protector test kit. While thependant is plugged in, actual trip and

close operations will be inhibited andthe amber float light will flash. Thependant has a display for the readoutof the set points and a keyboard toset them.

Factory default settings are pro-

grammed into each MPCV networkrelay, however each project and pro-tector application represents differentvoltage and loading conditions, whichcan require adjustment of the defaultsettings to other appropriate values.Experienced service technicians mustbe utilized when commissioningprotectors, and proper tools such asprotector test sets and programmingpendants must be used to startupprotectors and maintain the units.

Relay settings can also be implementedvia Eaton’s Cutler-Hammer PowerNetsoftware, which allows for the full

use of the communication features of the MPCV network relay as describedon the following pages. Non-Cutler-Hammer communication protocolsmay be able to interface with a subnet-work of MPCV relays through a dataconcentrator and an independentlywritten and supplied driver.

MPCV-D Relay (Front View) for CMD Protectors MPCV-D (Front View) for Existing G.E. Protectors

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17January 2003


Type MPCV Network Protector Relay —Communications ConfigurationsRef. No. 0477

Figure 17.1-7.Configuration #1 — Hardwired PowerNet Communication Network

Figure 17.1-8.Configuration #2 — Hardwired Remote Sites/Digital Communication Links through Multiple Cells

mpcv

mpcv mpcvmpcv

mpcv mpcv mpcv

mpcv mpcv mpcv

eolrResistor

VAULT #4

VAULT #3

VAULT #2

VAULT #1

TypicalNetworkRelay MPCV

To other PowerNet

network and devices

Network Card

PC with PowerNet Sof tware including Wavef orm Analysis —Provides communication between remote PC and each MPCV Network Relay:Data includes Trip Buff er, Wavef orm Analysis, Metering of Current, Voltages, Power,Power Factor, Harmonics and Status (Protector open / close, Temperature, Door open)

TypicalNetworkProtectors

Twisted Pair#18 AWG

BELDENCAT. 9473 or

IMPCABLE

coniPC

mpcv mpcv

mpcv mpcvmpcv

eolr

DIGITAL COMM.

MODEM

DIGITAL COMM.

MODEM

PC with Software

ToDigital Cell Site and

Digital Communication System

From REMOTESITES

andDIGITAL CommunicationSystem Links

PC with PowerNet Software —

Allows dial-up monitoring or

continuous monitoring of

REMOTE SITENetwork Systems

REMOTE SITE #1

mpcv mpcvmpcv

eolr

DIGITAL COMM.

MODEM

PC with Software



REMOTE SITE #1

mpcv mpcvmpcv

eolr

DIGITAL COMM.

MODEM

PC with Software



REMOTE SITE #1

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PowerNet Software for Type MPCV —Network Protector Communications RelaysRef. No. 0478

Control and MonitoringCapabilities from aPersonal Computer

Proven PowerNet software, devel-

oped by the Eaton’s Cutler-Hammerbusiness, provides an operator withthe capability to control networkprotectors from a personal com-puter…while simultaneously monitor-ing power quality and operatingconditions, providing this informationin real time.

Sample Monitoring Screen

PowerNet software is a user-friendly,Microsoft Windows-based programthat allows the operator to point andclick through the screens. Standard soft-ware screens are appropriate for mostapplications but can be customized tomeet your individual requirements.

PowerNet software is designed torun on any IBM compatible PC, 486Pentium or higher, that has: 16M RAMplus a 1 GB hard disk drive, a colormonitor, VGA video card, a keyboardand a mouse.

As a minimum, Microsoft Windows 95or NT software with Microsoft Excel is required.

A dedicated computer is not required.Word processing or other programscan be run while PowerNet continuesto monitor and log events.

Sample Set Point Screen

MonitoringPowerNet provides energy manage-ment, operations and equipmentstatus information, and offers theoperator these capabilities:

s Real-time information. The operatorcommands an inquiry to each MPCVRelay on the system which logs cur-rent, voltage, power (watts, vars andVA), energy, frequency, demand,power factor, and total harmonicdistortion (THD). This informationis displayed on a single screen.

Also displayed on this screen isnetwork protector inside air temper-ature. Additionally, from the samescreen, the operator can select toview the last trip waveform orreview the MPCV Relay setpoints.

s Data printout. Real-time informationfrom all MPCV Relays on any one

feeder can be printed out to providea near instantaneous load flow of the entire feeder. This informationis an important source for planningand emergency loading scenarios.

s Internal environment of the net-work protector enclosure. Waterinside the network housing andupper copper bus temperatures.Breaker status (open/closed).

s Vault environment. Transformertop oil temperature, water in thenetwork vault, fire alarm, andnetwork enclosure pressure.

ControlPowerNet provides multiple networkprotectors controlled from a remotelocation and allows the followingcapabilities:

s Close or trip the breaker relaycontacts. If the operator chooses tohave the breaker’s relay trip contact“make,” the breaker opening canbe viewed on-screen and listedcurrents will go to zero. A designed-in safety feature prevents thenetwork protector from being closedwhile the MPCV Relay trip contact is“made” until the relay trip responseis removed.

s Relay set points. The operator canreview or change the operational setpoints without using the hand-heldcontrolling pendant. Passwordprotected security helps preventaccidental or improper usage.

AlarmingPowerNet provides the operator withthese capabilities:

s Receive an alarm in real time.When an established parameter

of a monitoring function is reachedor exceeded, an alarm condition isdisplayed immediately on the PCscreen, enabling the operator to:

u Identify the vault or feeder inquestion.

u Determine what alarm has beentriggered and at what location.

This information is used to sendservice crews directly to the problem,rather than performing the timeconsuming tasks of checking eachnetwork protector on any one feeder.

An alarm will show graphically orsound audibly when an event occurs,

alerting the operator to a situationrequiring immediate attention. Alarmscan be removed from the screenonce they have been reviewed andacknowledged.

System Support and UpgradesAvailable support programs includeprogram design, network trouble-shooting, 24-hour service and soft-ware training. Software upgradesare available to customers who havealready purchased the program.

Additional Information

Details about communicationsrelays are available in SA-376 MPCVCommunications Relay. This literatureand other descriptive materials, includ-ing information about Cutler-HammerNetwork Protectors, are availablethrough your authorized Cutler-Hammerdistributor or sales engineer.

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17.1January 2003


CMD Network Protector SchematicRef. No. 0479

Typical Schematic Diagram

CMD Network Protector 480Y/277 Volts

Figure 17.1-9.Typical Schematic Diagram

BF4 BF3

BF4

5

RL

G

750

P.B.

T3T1 T2

T1A

T2B

T1

N1A

N2B

32

22T2

T3C

N3C

MPCV

MPCV

MPCV

M P C V

7

6

M P C V

T3

N3

N1A

N2 N2B

N1

11

N1 N2

N3C

3121

N2

G

21

N3

N3

T1

Control

Xfmr.

PS M

125

BF1

PF

G

T1

12

22

T2

G

32

T3

M P C V

IN3671

AC

208

+

-

60

48

BF2

75053

3

2

G1

60

BN

Jumper Plate

**

1200*

Dry Auxiliary Contacts Wired to Secondary Disconnects In Protector

BF3

BF4

52

44

L.O.

TRIP &

49E

TRIP

MPCR

JC

BF2

Xfmr. Side

31

21

11

12

38

28

18

23

13

33

12

10

11

9

G

8 7

15

8

Network Side

Secondary Disconnect51

B

50

A

To Protector

BF1 4 1

52B

40

52A

B

5 2

44B

3

1

44A

JA4

4

MPCR

5 4

- SCHEMATIC DIAGRAM -

5 7

5 8

Trip De

vice250V DC Coil

150 Ohms

A

49

(+)

AC

5 6

5 5

4 2

BF1

W

BR1

(-)

BF2

B

47

49A

4 6

MPCR

4

2

1

64

65

N2

67

62

63

15

16

05

13

14

TX

To

11

16

17 12

1318

B

11

12

OHMS

208

49E

BF4

49D

49C

BF3

For Remote Trip & L.O.

Via the Disconnect Cabinet(Optional)

Overcurrent & Ground Fault, & Lockout 125V DC Relay Cat #BFDF10S(Optional)

31

2

Phase Rotation

ConnectionRemote atDisconnect Cabinet

Legend – CMD Network Protectors

MPCV - MPCV Network Relay Terminal Number NJA & JC - Microswitch Contacts on External Operating HandleM -AC Charging Spring MotorW -Normally Open Contact

(Closed When Charging Springs)BF1 -AC Motor Closing RelayBF2 - AC Master Trip Relay to Prevent ClosureBF3 - DC Overcurrent & Ground Fault Lockout Relay

(Actuates from Remote 125V DC Control SourceThrough Remote Contacts-AC Option Available)

BF4 - AC Remote Trip and Lockout Relay(Actuates from AC Control in Protector throughRemote Contact Closure)

RL - Red Pilot Light for Monitoring CapacitorDischarge Before Maintenance

- Capacitor for Capacitive Trip System- Resistor

PB - Manual Pushbutton for Capacitor Discharge- Remote Contact Scheme on Network DisconnectCabinet (if Used) – Serves to Open Protector WhenDisconnect Cabinet Doors are Opened

Special Notes

1. *For remote trip and lockout, wires #44 and #52must be jumpered when unit is drawnout on rails fortesting. Also, wires #44 and #52 must be jumperedif lockout feature is not to be used.

2. **Pushbutton for capacitor discharge.

3. JA contact is closed when handle is in “Auto” position.

4. JC contact is closed when handle is in the“Closed” position.

5. When the drawout unit is in the connected position,contacts JA and JC are operated by the handlemechanism.

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Type CM52Ref. No. 0480

Type CM52 Network Protectors

Typical Enclosed CM52 Network Protector

Quality Designed to be Smarter, Safer and Streamlined

The new Eaton’s Cutler-Hammer CM52 Network Protectorprovides the highest level of reliability and service continuityavailable today. An intelligent protective device, the CM52Network Protector is designed to handle ratings from 800 to6200 amps, 216 to 600 volts. This new network protector fea-tures an electrically operated, composite case, spring closedair network circuit breaker controlled by the Cutler-Hammer

MPCV network relay.The CM52 meets or exceeds the standards in IEEE C57.12.44.This ensures a product with the highest performance stan-dard applicable to a network protector. A first for networkprotectors, the CM52 is setting a new standard by beingUL-qualified. This third party approval certifies the deliveryof a quality product. A UL-qualified network protector meanseasier code approval for quicker system start-up and lessapproval time and costs in a non-utility environment.

CM52 Protector Faceplate

Network Protector Ratings

Several network protector models currently exist to satisfyall location requirements. The new CM52 design covers allof these ratings, giving you one type of protector to handleall installation needs. The styles available include internal orexternal fuse mountings and submersible or NEMA enclo-sures throughout the current and voltage ratings. Havingparts and accessories common through all protector ratingsmeans lower maintenance and inventory costs. The CM52was also designed with higher interrupting and fault closeratings than existing protector models. This higher ratingallows for safer installations and better protection on anetwork system.

Table 17.1-2.CM52 Ratings Table — Ratings through 480 Volts Wye

ContinuousCurrentRating

InterruptingRating

Closeand LatchRating

Suggested TransformerRating (kVA)

216V 480V

80012001600/1875

424242

353535

225300500

500750

1000

20002500/28253000

426565

354545

600750

1000

100015002000

250045006200

858585

656565

100010001000

200020002000

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17.1January 2003


Type CM52Ref. No. 0481

Type CM52 Network Protectors

CM52 Secondary Contacts

Protector downtime is both frustratingand costly. No adjustments, few

replacement parts, color-coded wiring,diagnostics, and a protected motor arekey contributors to the high-level ser-vice reliability and reduced downtimeof the Eaton’s Cutler-Hammer CM52Network Protector.

CM52 Voltage Regulator Device

The CM52 is a low maintenance networkprotector. It requires no adjustments, iseasier to troubleshoot and has built-indiagnostics. Maintenance time is nolonger needed for the adjustment of protector contacts. Troubleshootingis much easier with the CM52 throughcolor-coded wiring and a front accessi-ble test switch. Diagnostics are builtin to the Voltage Regulator Device(VRD). The VRD is a solid-state designto deliver regulated power to the motorand trip device without using a calibra-tion-adjusting resistor. With the newCM52, maintenance becomes easierand protector downtime decreases,saving money and increasing reliability.

CM52 is UL Labeled

Much more manageable at lessthan half the weight of older network

protectors, the protector is easier tohandle, resulting in less time in vaults,and lower labor costs. A four-position,draw-out, deadfront circuit breakermakes testing quick and safe, curbingmaintenance time and costs. The dead-front provides worker safety, drasti-cally reducing the possibility of liveelectricity accidents during inspection.A front accessible 9-point test switchprovides safe and easy connectionof test equipment during testingand troubleshooting.

Quality was the focus through thedesign to the manufacturing of thenew CM52 Network Protector. Thecircuit breaker in the CM52 goesthrough a 100-point testing procedurein an ISO 9000 breaker specialtyplant. The quality design and testingof the CM52 virtually eliminates theneed for later adjustments andinsures a reliable product.

The Intelligence of theProtector — MPCV Relay

Within the CM52 lies its intelligence,the MPVC Network Relay. The pro-grammable MPCV Network Relay

brings the proven performance of microprocessor-based technologyto the new Cutler-Hammer CM52Network Protector.

This programmable relay offers multi-ple selections to meet the require-ments of each network protectorinstallation. With the MPCV, you canselect between the traditional straight-line master close curve and modifiedcircular close curve. Our enhancedsequence-based algorithm providesexceptional performance and stabilityover a wide range of temperaturesand voltages in comparison with a

power-based algorithm. Additionally,the anti-pumping feature on the MPCVrelay protects the motor under damag-ing system conditions.

CommunicationsThe MPCV relay has built in communi-cation capabilities for monitoringand control of the network protector.This allows you to access and displayinformation from the relay includingvoltage, current, energy usage, powerquality, and last trip details. Control of the protector is possible from a remotelocation, providing safer conditionsand quicker response time.

The relay can also communicate otherinformation about the network protec-tor’s environment through standardauxiliary inputs. Information such aswater inside the network housing, orerratic internal enclosure temperaturewill send an alert notifying of prob-lems in the vault.

The relay has the capability of commu-nicating information to a Data Concen-trator/Translator (DC/T) over a shieldedtwisted pair of communications wires.Information is obtained through a util-ity’s SCADA protocol and/or the Cutler-Hammer PowerNet software program.

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Ref. No. 0482


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17January 2003

Spot Network EquipmentRating Selection

Spot Network Equipment Selector GuideRef. No. 0483

Figure 17.2-1 illustrates the generalconfiguration of the network equip-ment for Tables 17.2-2 through 17.2-5equipment values. For three-unit spotnetworks, the fourth transformer/pro-tector pair and load L4 bus and load donot exist. For two-unit spot networks,the third and fourth transformer/protec-tor pairs and load L3 and L4 busesand loads do not exist. Tables 17.2-2 through 17.2-5 are developed forsystems anticipating only one primaryfeeder outage, and secondary voltageis 480 wye or 208 wye respectively.

Table 17.2-1.CMD, CM-22, and CMR ProtectorComparison

ᕃ Strongly recommended for spot networkapplications. Used optional stored energymechanism on two transformer spotnetworks.

ᕄ Type NPL silver sand fuses have been testedup to 150,000 amperes at 600 volts.

ᕅ CMR-8 fuses are alloy type at 4500A, butchange to externally mounted current-limiting silver sand mounted remotefrom the protector, such as a disconnector fuse truck.

ᕆ NPL fuses can be mounted in epoxyenclosures or network disconnect cabinets.

Features Model or Type Protector

CMD ᕃ CM-52 ᕃ CMR-8

ContinuousCurrentRatings inAmperes

800-3000A

800-4500A

4500-5100A

OperatingMechanism

SpringClose

SpringClose

SpringClose

Closeand LatchRatingAvailable

YES YES YES

MechanismWithdrawal

Drawout Drawout Rollout

MechanicalLife (No. Ops)

10,000 10,000 10,000

WithdrawnConstruction

Dead-front

Dead-front

Live-front

ProtectorFuse Type

Silver-SandNPLType ᕄ

Silver-SandNPLType

LeadAlloy/ Silver-Sand ᕅ

FuseLocation

Externalᕆ

Externalᕆ

InternalExternal

ProtectorTrip Device

CapacitorTrip

ShuntTrip

ShuntTrip

DielectricTest Passed

5000V 2200V 2200V

Figure 17.2-1.Spot Network Configurations

Table 17.2-2.Spot Network Equipment Ratings for Liquid Transformers —480V Secondaries Liquid Transformers (Including Oil and Silicone) OA 55°C Risewith 138% Short Time Capacity (Up to 24 Hours for Probable Sacrifice of 1% Life)

Table 17.2-3.Spot Network Equipment Ratings for Dry Transformers —480V Secondaries Dry-Type Transformers (Including VPI, VPE and Cast Coil) AA/FA 80°C Risewith 150% Overload Capacity (Continuous when Fan Cooling is Active and Ambient is 30°C)

Total NetworkTX kVA Nominal

TL = Load kVA(Maximum forOne PRI Outage)

TX = Network TXkVA (55°C Liquid)

NP = ProtectorAmpacity at 480V

LV Switchgear TieBreaker Frame/Trip Amperes

Two-Unit Spot Network TL = L1+L2 and L3 = L4 = 0

1000

15002000

690

10351380

500

7501000

1200

16001875

800/800AT

1600/1200AT1600/1600AT

300040005000

207027603450

150020002500

250035004500

3200/2200AT4000/3200AT4000/4000AT

Three-Unit Spot Network TL = L1+L2+L3 and L4 = 0

150022503000

138020702760

500750

1000

120016001875

800/800AT1600/1200AT1600/1600AT

450060007500

414055206900

150020002500

250035004500

3200/2200AT4000/3200AT4000/4000AT

Four-Unit Spot Network TL = L1+L2+L3+L4

200030004000

207031054140

500750

1000

120016001875

800/800AT1600/1200AT1600/1600AT

6000800010000

6210828010350

150020002500

250035004500

3200/2200AT4000/3200AT4000/4000AT


TL = Load kVA(Maximum forOne PRI Outage)

TX = Network TXkVA (80°C Dry)

NP = ProtectorAmpacity at 480V

LV Switchgear TieBreaker Frame/Trip Amperes


100015002000

75011251500

500750

1000

120016001875

1600/1000AT1600/1400AT2000/1600AT

300040005000

225030003750

150020002500

282535004500

3200/2600AT4000/3200AT4000/4000AT


150022503000

500750

1000

500750

1000

1600/1000AT1600/1400AT2000/1600AT

450060007500

450060007500

150020002500

250035004500

3200/2600AT4000/3200AT4000/4000AT


200030004000

225033754500

500750

1000

120016001875

1600/1000AT1600/1400AT2000/1600AT

60008000

10000

67509000

11250

150020002500

250035004500

3200/2600AT4000/3200AT4000/4000AT

LOADSL1

LOADSL2

LOADSL3

LOADSL4

TL = L1 + L2 + L3 + L4 = Total Network Load kVA

TX

NP

Tie

TX

NP

Tie

TX

NP

Tie

TX

NP

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Rating Selection

Spot Network Equipment Selector GuideRef. No. 0484

Table 17.2-4.Spot Network Equipment Ratings for Liquid Transformers — 216Y or 208Y Secondaries Liquid Transformers(Including Oil and Silicone) OA 55°C Rise with 138% Short Time Capacity (Up to 24 Hours for Probable Sacrifice of 1% Life)

ᕃ For the listed table Total Load values (TL) protector ratings are not available. However, protector ratings are available through 5000 amperes which willsupport reduced TL (Total Load) values of 1871 kVA, 3742 kVA and 5613 kVA for two-unit, three-unit, and four-unit spot networks, respectively at 216Yvolt secondary (4% less load values are supported if 208Y is the system voltage).

Note:NA indicates that spot networks are not available.

Table 17.2-5.Spot Network Equipment Ratings for Dry Transformers — 216Y or 208Y Secondaries Dry Transformers (Including VPI, VPEand Cast Coil) AA/FA 80°C Rise with 150% Overload Capacity (Continuous when Fan Cooling is Active and Ambient is 30°C)

ᕄFor the listed table Total Load values (TL) protector ratings are not available. However, protector ratings are available through 5000 amperes which willsupport reduced TL (Total Load) values of 1871 kVA, 3742 kVA and 5613 kVA for two unit, three unit, and four unit spot networks, respectively at 216Yvolt secondary (4% less load values are supported if 208Y is the system voltage).

Note:NA indicates that spot networks are not available.


TL = Load kVA (Maximumfor One PRI Outage)

TX = Network TX kVA(55°C Liquid)

NP = ProtectorAmpacity at 216V or 208V

LV Switchgear Tie BreakerFrame/Trip Amperes


1000

15002000

690

10351380

500

7501000

2000

30004500

2000/1900AT

3200/2800AT4000/4000AT

300040005000

207027603450

150020002500

ᕃ

N/AN/A

5000/5000ATN/AN/A


150022503000

138020702760

500750

1000

200030004500

2000/1900AT3200/2800AT4000/4000AT

450060007500

414055206900

150020002500

ᕃ

N/AN/A

5000/5000ATN/AN/A


200030004000

207031054140

500750

1000

200030004500

2000/1900AT3200/2800AT4000/4000AT

60008000

10000

62108280

10350

150020002500

ᕃ

N/AN/A

5000/5000ATN/AN/A


TL = Load kVA (Maximumfor One PRI Outage)

TX = Network TX kVA(80°C Dry)

NP = ProtectorAmpacity at 216V or 208V

LV Switchgear Tie BreakerFrame/Trip Amperes


100015002000

75011251500

500750

1000

225035004500

2000/1900AT3200/3100AT4000/4000AT

3000

40005000

2250

30003750

1500

20002500

ᕄ

N/AN/A

5000/5000AT

N/AN/A


150022503000

150022503000

500750

1000

225035004500

2000/1900AT3200/3100AT4000/4000AT

450060007500

450060007500

150020002500

ᕄ

N/AN/A

5000/5000ATN/AN/A


200030004000

207031054140

500750

1000

225035004500

2000/1900AT3200/3100AT4000/4000AT

60008000

10000

62108280

10350

150020002500

ᕄ

N/AN/A

5000/5000ATN/AN/A

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17January 2003

Spot Network EquipmentRating Selection

Protector Application InformationRef. No. 0485

Table 17.2-6.Transformer and Protector Combinations and Protector Ratings

ᕃ The interrupting rating exceeds the available fault current from the transformer.ᕄ The short time rating of protectors without fuses equals the interrupting rating.ᕅ CM-52 protector ratings may be slightly higher. See Table 17.1-2 on Page 17.1-12.ᕆ Close and latch ratings only apply to protectors having spring close or stored energy mechanisms, such as CMD and CM-52 models.

Note:Use this table and its equipment ratings when designing network systems where the protectors are rated lower or higher, as apercentage of the full load amperes of the transformers, than those selected in the Tables 17.2-2 through 17.2-5. This table is also usefulwhen selecting equipment ratings for systems which anticipate more than one single primary outage, e.g., when two outages are expectedon a four-transformer spot network.

Network Transformer Network Protectors

TransformerNameplatekVA Rating

Full Load Currentrms Amperes

ContinuousCurrent Ratingrms Amperes

Protector Ratingas % of TransformerFull Load Current

Interrupting Rating inrms SymmetricalAmperes ᕃᕄᕅ

Close and Latch Ratingin rms SymmetricalAmperes ᕅᕆ

System Voltage = 216Y/125 or 208Y/120

225300500

600800

1333

80012001600

133150120

30,00030,00030,000

25,00030,00025,000

500500500

133313331333

187520002250

141150169

30,00035,00035,000

25,00035,00035,000

750750

1000

200020002667

250028253000

125141112

60,00060,00060,000

40,00040,00040,000

10001000

26672667

35004500

131169

60,00060,000

40,00060,000

System Voltage = 480Y/277

500750

1000

600900

1200

80012001600

133133133

30,00030,00030,000

25,00025,00025,000

10001000

1000

12001200

1200

18752000

2250

158167

188

30,00035,000

35,000

25,00035,000

35,000

150015002000

180018002400

250028253000

139157125

45,00045,00045,000

40,00040,00040,000

200025002500

240030003000

350045005000

145150167

45,00060,00060,000

40,00060,00060,000

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Ref. No. 0486


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17January 2003

Spot Network EquipmentLayout Dimensions

Liquid Type Network Unit DimensionsRef. No. 0487

Figure 17.3-1.Liquid Network Unit Dimensions and Weights, Indoor Design

Note:Dimensions are approximate for silicone filled network transformers and are typical for the ratings indicated. Designs can becustomized to fit into existing spaces in many instances, although at higher cost. Specifiers are encouraged to consult the Eaton’s Cutler-Hammer business to facilitate special existing conditions.

Table 17.3-1.Liquid Network — Dimensions in Inches (mm)

ᕃ Protector selected at 480 volts per Table 17.2-2 recommendations.ᕄ Consult the Cutler-Hammer business for network disconnect information. If disconnect is remote from this location, then the transition box at top of

protector is 30 – 36 inches (762.0 – 914.4 mm) above protector flange.

Table 17.3-2.Liquid Network — Weights in Lbs. (kg)

ᕅ Weights for transformers include the fluid weight.ᕆ The number of gallons of liquid includes the fluid inside the primary switch.ᕇ Consult the Cutler-Hammer business for network disconnect information. If disconnect is remote from this location, then the transition box at top of


D

32(812.0)

SW

18

(457.2) WP

TX

Plan View

ND

NPDN

DD

HP HL NP

TX

SWHT

ND

HN

12(304.8)

H

Front

LiquidTransformer

Legend:SW = PrimaryTX = Network Transformer (Silicone filled)NP = Network ProtectorND = Network Disconnect (Non-loadbreak)

Front View

WT

Neutral

W All dimensions are shown in Tables 17.3-1 and 17.3-2.

NetworkEquipment

Dimensions — Refer to Plan and Front View Figures Above

TXkVA

NP ᕃ Amps

HT HP HL HN H WT WP W DN DD D

500750

1000

120016001875

64 (1625.6)67 (1701.8)77 (1955.8)

49 (1244.6)50 (1270.0)54 (1371.6)

40 (1016.0)43 (1092.2)54 (1371.6)

52 (1320.8)55 (1397.0)66 (1676.4)

106 (2692.4)109 (2768.6)120 (3048.0)

50 (1270.0)53 (1346.2)56 (1422.4)

34 (863.6)34 (863.6)34 (863.6)

102 (2590.8)105 (2667.0)108 (2743.2)

32 (812.8)32 (812.8)32 (812.8)

34 (863.6)34 (863.6)34 (863.6)

42 (1066.8)45 (1143.0)48 (1219.2)

150020002500

250035004500

83 (2108.2)90 (2286.0)93 (2362.2)

57 (1447.8)61 (1549.4)63 (1600.2)

55 (1397.0)65 (1651.0)67 (1701.8)

69 (1752.6)74 (1879.6)90 (2286.0)

123 (3124.2)ᕄ

ᕄ

62 (1574.8)66 (1676.4)68 (1727.2)

36 (914.4)38 (965.2)42 (1066.8)

116 (2946.4)122 (3098.8)128 (3251.2)

38 (965.2)38 (965.2)48 (1219.2)

34 (863.6)ᕄ

ᕄ

55 (1397.0)63 (1600.2)68 (1727.2)

NetworkEquipment

Weights in Lbs.(kg)

Liquid Gallons(Liters)

TXkVA

NPAmps

Network TX ᕅ Protector NP Network Disconnect Network TX ᕆ

500750

1000

120016001875

7800 (3541)10,600 (4812)11,400 (5176)

850 (386)850 (386)850 (386)

250 (114)300 (136)350 (159)

220 (833)250 (946)320 (1211)

150020002500

250035004500

16,100 (7309)21,000 (9534)24,000 (10,896)

1200 (545)1450 (658)1500 (681)

400 (182)ᕇ

ᕇ

500 (1893)600 (2271)700 (2650)

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Layout Dimensions

Dry-Type Network Unit DimensionsRef. No. 0488

Figure 17.3-2.Dry-Type Network Unit Dimensions and Weights, Indoor Design

Note:Dimensions and weights are for standard VPI or VPE Dry-Type designs, 80°C rise with fans with 150% continuous overload capacity andaluminum windings. Copper windings add more weight. Primary voltage is 15 kV, 95 kV BIL insulation.

Table 17.3-3.Dry-Type Network — Dimensions in Inches (mm)

ᕃ Protector selected at 480 volts per Table 17.2-3 recommendations.ᕄ Dimensions for overall width include a bussed transition — 20 inches (508.0 mm) on the primary. This 20-inch (508.0 mm) section may be eliminated

by using cable connections to primary bushing in lieu of buswork.ᕅ Consult the Eaton’s Cutler-Hammer business for network disconnect information. If disconnect is remote from this location, then the transition box

at top of protector is 30 – 36 inches (762.0 – 914.4 mm) above protector flange.

Table 17.3-4.Dry-Type Network — Weights in Lbs. (kg)

ᕆ Dimensions and weights are for standard VPI or VPE Dry-Type designs, 80°C rise with fans with 150% continuous overload capacity and aluminumwindings. Copper windings add more weight. Primary voltage is 15 kV, 95 kV BIL insulation.

ᕇ Protector stand carries the weight of the protector, since the dry-type end sheets do not have the strength to support the weight of the protector.ᕈ Consult the Cutler-Hammer business for network disconnect information. If disconnect is remote from this location then the transition box at top of


Legend:SW= PrimaryTX = Network Transformer (Silicone filled)NP = Network ProtectorND = Network Disconnect (Non-loadbreak)

SW TX

HP

HLNP

TXSW

HT

ND

Front

Dry TypeTransformer

Plan View Front View

ND

NP DDD

W

20(508.0)

WT

DN

Front

HN

H

FrontDry TypeTransformer

18 (457.2)

WP

Neutral

36(914.4)

12(304.8)

NetworkEquipment


TXkVA

NP ᕃ Amps

HT HP HL HN H WT WP W ᕄ DN DD D

500750

1000

120016001875

90 (2286.0)90 (2286.0)

102 (2590.8)

90 (2286.0)90 (2286.0)90 (2286.0)

56 (1422.4)56 (1422.4)56 (1422.4)

69 (1752.6)69 (1752.6)69 (1752.6)

123 (3124.2)123 (3124.2)123 (3124.2)

90 (2286.0)102 (2590.8)102 (2590.8)

34 (863.6)34 (863.6)34 (863.6)

180 (4572.0)192 (4876.0)192 (4876.0)

32 (812.8)32 (812.8)32 (812.8)

34 (863.6)34 (863.6)34 (863.6)

66 (1676.4)66 (1676.4)66 (1676.4)

150020002500

250035004500

102 (2590.8)112 (2844.8)120 (3048.0)

90 (2286.0)90 (2286.0)90 (2286.0)

60 (1524.0)64 (1625.6)66 (1676.4)

75 (1905.0)81 (2057.4)90 (2286.0)

129 (3276.6)ᕅ

ᕅ

102 (2590.8)124 (3149.6)130 (3302.0)

36 (914.4)38 (965.2)42 (1066.8)

194 (4927.6)218 (5537.2)226 (5740.4)

38 (965.2)38 (965.2)48 (1219.2)

34 (863.6)ᕅ

ᕅ

66 (1676.4)66 (1676.4)66 (1676.4)

NetworkEquipment

Weights in Lbs. (kg)

TXkVA

NPAmps

Primary SW + Fuses Network TX ᕆ Protector NP + Stand ᕇ Network ND Disconnect

500750

1000

120016001875

2000 (908)2000 (908)2000 (908)

5600 (2542)6700 (3042)8450 (3836)

950 (431)950 (431)950 (431)

250 (114)300 (136)350 (159)

150020002500

250035004500

2000 (908)2000 (908)2000 (908)

10,150 (4608)13,150 (5970)16,000 (7264)

1330 (604)1550 (704)1600 (726)

400 (182)ᕈ ᕈ

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17January 2003

Spot Network EquipmentLayout Dimensions

Dry-Type Network Unit — Switchgear Mounted Protector DimensionsRef. No. 0489

Figure 17.3-3.Dry-Type Network Unit Dimensions and Weights, Indoor Design with Switchgear Mounted Protector

Note:Dimensions and weights are for standard VPI or VPE Dry-Type designs, 80°C rise with fans with 150% continuous overload capacityand aluminum windings. Copper windings add more weight. Primary voltage is 15 kV, 95 kV BIL insulation.

Table 17.3-5.Dry-Type with Switchgear Mounted Protector — Dimensions in Inches (mm)

ᕃ Protector selected at 480 volts per Table 17.2-3 recommendations.ᕄ Primary transition section 20 inches (508.0 mm) in width may be eliminated by using cable interconnections. Elimination of transition reduces

width by 20 inches (508.0 mm).ᕅ Dimensions are approximate for low voltage switchgear construction. Close-coupling to switchgear structures with Main and Feeders will

require 72 – 78 inch (1828.8 – 1981.2 mm) depth depending upon the type of feeders used, fused or nonfused. When switchgear is remote,

using cable or busway connections, the depth of the Protector section can be reduced to 72 inches (1828.8 mm).ᕆ Consult the Eaton’s Cutler-Hammer business on availability of 4500A CMR-8 Protector in switchgear mounting.

Table 17.3-6.Dry-Type with Switchgear Mounted Protector — Weights in Lbs. (kg)

ᕇ Dimensions and weights are for standard VPI or VPE Dry-Type designs, 80°C rise with fans with 150% continuous overload capacity andaluminum windings. Copper windings add more weight. Primary voltage is 15 kV, 95 kV BIL insulation.

ᕈ

Consult the Cutler-Hammer business on availability of 4500A CMR-8 Protector in switchgear mounting.

HP

NPTXSW

HT

Legend:SW= PrimaryTX = Network Transformer (Silicone filled)NP = Network ProtectorND = Network Disconnect (Non-loadbreak)(1) = Primary Transition Section May Be Eliminated

By Using Cable Interconnections

(2) = Protector Structure May Be Close-Coupled ToSwitchgear Without Transition

Plan View Front View

Dry TypeTransformer

(1)

HN

SwitchgearMounted

(2)

H

ToSwitchgear

DPNP

TXSW

Plan View

Dry TypeTransformer

Low-VoltageSwitchgear

(2)

D

Front

W

WT 7136(914.4)

20(508.0)

(1)

NetworkEquipment


TXkVA

NP ᕃ

AmpsHT HP HN H WT W ᕄ DP D ᕅ

500750

1000

120016001875

90 (2286.0)90 (2286.0)

102 (2590.8)

90 (2286.0)90 (2286.0)90 (2286.0)

96 (2438.4)96 (2438.4)96 (2438.4)

90 (2286.0)90 (2286.0)

102 (2590.8)

102 (2590.8)102 (2590.8)102 (2590.8)

228 (5791.2)228 (5791.2)228 (5791.2)

66 (1676.4)66 (1676.4)66 (1676.4)

78 (1981.2)78 (1981.2)78 (1981.2)

150020002500

250035004500

102 (2590.8)112 (2844.8)—

90 (2286.0)90 (2286.0)—

96 (2438.4)96 (2438.4)—

102 (2590.8)112 (2844.8)—

112 (2844.8)112 (2844.8)—

238 (6045.2)238 (6045.2)ᕆ

66 (1676.4)66 (1676.4)—

78 (1981.2)78 (1981.2)—

NetworkEquipment

Weight in Lbs.(kg)

TXkVA

NPAmps

Primary SWIncluding Power Fuses

Network TransformerTX ᕇ

Low Voltage Switchgearand Protector NP

500750

1000

120016001875

2000 (908)2000 (908)2000 (908)

5600 (2542)6700 (3042)8450 (3836)

4000 (1816)4000 (1816)4000 (1816)

150020002500

250035004500

2000 (908)2000 (908)—

10,150 (4608)13,150 (5970)—

4400 (1998)4600 (2088)ᕈ

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Layout DimensionsRef. No. 0490

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