IB-51000B

POWELL

INDUSTRIES, INC.

IB-51000BINSTRUCTIONS

POWELL ELECTRICAL MANUFACTURING COMPANY8550 MOSLEY DRIVE • HOUSTON, TEXAS 77075 USA

PHONE (713) 944-6900 • FAX (713) 947-4453http://www.powellelectric.comhttp://www.powellservice.com

©2001 POWELL ELECTRICAL MANUFACTURING COMPANY ALL RIGHTS RESERVED REVISION 11/2003

Installation Maintenance Renewal Parts

Series P-51000 PowlVac®

Metal-clad Switchgear

with Vacuum Circuit Breaker

4.16 KV, 7.2 KV and 13.8 KV Voltage Classes

P-51000 PowlVac® Metal-clad Switchgear IB-51000B

ContentsSection Page

I. INTRODUCTION ............................................................................................................. 5A. SCOPE ................................................................................................................................................. 5B. PURPOSE ............................................................................................................................................ 5C. CONFLICT WITH OTHER DOCUMENTS ........................................................................................... 5D. OTHER ITEMS OF CAUTION .............................................................................................................. 5E. INSTRUCTION BULLETINS ON THE WEB......................................................................................... 5

II. SAFETY .......................................................................................................................... 5A. GENERAL ............................................................................................................................................ 6B. SPECIFIC SAFETY RULES ................................................................................................................. 6C. X-RAYS ................................................................................................................................................ 6D. SAFETY LABELS ................................................................................................................................. 7

III. DESCRIPTION................................................................................................................ 8A. GENERAL ............................................................................................................................................ 8

1) One-high Construction ...................................................................................................................82) Two-high Construction ...................................................................................................................8

B. SECONDARY COMPARTMENT .......................................................................................................... 9C. PRIMARY COMPARTMENT ................................................................................................................ 9D. VOLTAGE RATINGS ............................................................................................................................ 9E. LIGHTING IMPULSE WITHSTAND (BIL) ............................................................................................. 9F. FACTORY DIELECTRIC TEST ............................................................................................................ 9G. CIRCUIT BREAKER: THE REMOVABLE ELEMENT ......................................................................... 10H. SAFETY INTERLOCKS AND PROVISIONS ..................................................................................... 10

1) Positions Interlocks ..................................................................................................................... 102) Circuit Breaker Compartment Safety Provisions ..........................................................................10

I. CIRCUIT BREAKER RACKING MECHANISM ................................................................................... 111) Disconnected position .................................................................................................................. 112) Test Position ................................................................................................................................123) Connected Position ...................................................................................................................... 12

J. CIRCUIT BREAKER OPERATION ..................................................................................................... 12K. AUXILIARY ENCLOSURES AND COMPARTMENTS ........................................................................ 13L. ANTI-CONDENSATION HEATERS .................................................................................................... 13M. VOLTAGE (POTENTIAL) TRANSFORMER (ROLLOUT CARRIAGE) ............................................... 13N. FUSE DISCONNECTING DEVICE (ROLLOUT CARRIAGE) ............................................................. 14O. CURRENT TRANSFORMERS (THROUGH-TYPE) ........................................................................... 14P. MAIN BUS, MAIN BUS TAPS, AND GROUNDS ................................................................................ 14Q. PRIMARY DISCONNECT DEVICES AND SUPPORTS ..................................................................... 14R. LIGHTING .......................................................................................................................................... 15

IV. INSTALLATION............................................................................................................. 15A. GENERAL .......................................................................................................................................... 15B. RECEIVING........................................................................................................................................ 15C. STORAGE .......................................................................................................................................... 15D. HANDLING ......................................................................................................................................... 16E. POSITIONING THE METAL-CLAD SWITCHGEAR ........................................................................... 16

1) Drawings and Diagrams ............................................................................................................... 16F. PREPARATION OF FLOOR-ANCHORING ........................................................................................ 17

1) Indoor Metal-clad Switchgear ....................................................................................................... 172) Outdoor Metal-Clad Switchgear ................................................................................................... 17

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Section Page

G. DOOR ALIGNMENT ........................................................................................................................... 181) Door Alignment Conditions ...........................................................................................................182) Aligning Switchgear Doors ...........................................................................................................18

H. THE REMOVABLE ELEMENT ........................................................................................................... 18I. GROUNDING ..................................................................................................................................... 19J. CONNECTIONS ................................................................................................................................. 19K. MAIN BUS ASSEMBLY INSULATION ................................................................................................ 20

1) Wrapping Bus Joint ...................................................................................................................... 212) Applying PVC Boots ..................................................................................................................... 213) Cleaning Bus Insulation ............................................................................................................... 21

L. PRIMARY CABLES ............................................................................................................................ 21M. INSULATING PRIMARY CABLES TERMINATIONS .......................................................................... 22N. GROUND FAULT CURRENT TRANSFORMERS (THROUGH TYPE) ............................................... 22O. CONTROL CABLES ........................................................................................................................... 23P. SURGE PROTECTOR ....................................................................................................................... 23Q. ROOF ENTRANCE BUSHING ........................................................................................................... 23R. VOLTAGE TRANSFORMER (VT), CONTROL POWER TRANSFORMER (CPT), AND FUSE

ROLLOUT CARRIAGES .................................................................................................................... 231) Control Power Transformer Rollout .............................................................................................. 232) Fuse Rollout ................................................................................................................................. 24

V. OPERATION ................................................................................................................. 24A. GENERAL .......................................................................................................................................... 24

1) Inserting the Circuit Breaker into the Compartment ...................................................................... 242) Removing a Circuit Breaker from the Upper Compartment .......................................................... 253) Electrical Operation ...................................................................................................................... 254) Shutters ....................................................................................................................................... 255) Racking Mechanism..................................................................................................................... 276) Floor Pan ..................................................................................................................................... 277) Truck-Operated Cell Switch (TOC) (Optional) .............................................................................. 278) Removable Element Position Interlock (Optional) ........................................................................ 289) Mechanism-Operated Cell Switch (MOC) (Optional) ....................................................................2810) Secondary Disconnect Device .....................................................................................................2911) Dummy Removable Element ....................................................................................................... 3012) Ground and Test Device ............................................................................................................... 30

B. TEST AND INSPECTION ................................................................................................................... 31VI. MAINTENANCE ............................................................................................................ 32VII. RECOMMENDED RENEWAL PARTS AND REPAIR PROCEDURE ........................... 33

A. ORDERING INSTRUCTIONS ............................................................................................................ 34B. RECOMMENDED RENEWAL PARTS ............................................................................................... 34

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Contents


Figures

Tables

Figure Page

Table Page

Figure 1. Typical Metal-Clad Switchgear Line-up ...............................................................................................8Figure 2. One-high Basic Construction ..............................................................................................................8Figure 3. Two-high Basic Construction ..............................................................................................................9Figure 4. Interior Metal-clad Switchgear ...........................................................................................................10Figure 5. PowlVac® Vacuum Circuit Breaker ................................................................................................... 11Figure 6. Front Description of Circuit Breaker .................................................................................................. 11Figure 7. Circuit Breaker Cover Removed ....................................................................................................... 12Figure 8. Unit Space Heater .............................................................................................................................13Figure 9. Voltage Transformer and Rollout Carriage ........................................................................................ 13Figure 10. Control Power Transformer (Rollout Carriage) .................................................................................. 14Figure 11. Lifting Method for Switchgear ............................................................................................................16Figure 12. Recommended Floor ........................................................................................................................17Figure 13. Anchoring of Units with Channel Base .............................................................................................. 18Figure 14. Ground Bus Splice Assembly ............................................................................................................20Figure 15. Proper Bolt Assembly ........................................................................................................................20Figure 16. Wrapping of Bus ............................................................................................................................... 21Figure 17. Taping of Roof Bushing .....................................................................................................................22Figure 18. Rear View of Two-High Unit and Ground Fault Transformer ............................................................. 22Figure 19. Angle Shipping Bracket .....................................................................................................................23Figure 20. Shutters ............................................................................................................................................25Figure 21. Recommended Method for Lifting Circuit Breaker To Upper Cell ......................................................26Figure 22. Closed Door Racking ........................................................................................................................27Figure 23. Typical Compartment Door ...............................................................................................................28Figure 24. Position Interlock ..............................................................................................................................28Figure 25. Lower Mechanism-Operated Cell Switch (MOC) and Operating Mechanism ...................................29Figure 26. Upper Mechanism-Operated Cell Switch (MOC) and Operating Mechanism ....................................29

Table A. PowlVac® Metal-clad Switchgear ....................................................................................................... 9Table B. Bolt Torque Values for PowlVac® Metal-clad Switchgear ....................................................................20Table C. Accessories ........................................................................................................................................ 35Table D. Troubleshooting Topics ........................................................................................................................ 36

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WARNING

THIS EQUIPMENT MAY CONTAIN HIGH VOLTAGES AND CURRENTS WHICH CAN CAUSE SERI-OUS INJURY OR DEATH.

THE EQUIPMENT IS DESIGNED FOR USE, INSTALLATION, AND MAINTENANCE BY KNOWLEDGE-ABLE USERS OF SUCH EQUIPMENT HAVING EXPERIENCE AND TRAINING IN THE FIELD OFHIGH VOLTAGE ELECTRICITY. THIS DOCUMENT, AND ALL OTHER DOCUMENTATION SHALL BEFULLY READ, UNDERSTOOD, AND ALL WARNINGS AND CAUTIONS SHALL BE ABIDED BY. IFTHERE ARE ANY DISCREPANCIES OR QUESTIONS, THE USER SHALL CONTACT POWELL ELEC-TRICAL MANUFACTURING COMPANY IMMEDIATELY AT 1-800-480-7273.

CAUTION

Before any adjustment, servicing, parts replacement, or any other act is performed requiringphysical contact with the electrical working components or wiring of this equipment, the POWERSUPPLY MUST BE DISCONNECTED. Failure to follow this caution may result in injury or death.

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IMPORTANT

The information in this Instruction Bulletin is not intended to explain all details or variations of themetal-clad switchgear with circuit breakers, nor to provide for every possible contingency or hazardto be met in connection with installation, testing, operation, and maintenance of the equipment. Foradditional information and instructions for particular problems, which are not presented sufficientlyfor the user’s purposes, contact Powell Electrical Manufacturing Company at 1-800-480-7273.

I. INTRODUCTION

A. SCOPE

This instruction bulletin describes the followingPowlVac® Metal-clad Switchgear: IB-50000, IB-60000,IB-60200 PowlVac® Vacuum Circuit Breakers.

B. PURPOSE

This instruction bulletin provides:

1. Guidelines for safety

2. A general description of the operation and mainte-nance of the metal-clad switchgear

3. Instructions for installation and placing the metal-clad switchgear into service

4. Instructions for part replacement

5. Lists of renewal parts: Accessory List, Table C

6. Procedures for critical adjustments

7. Illustrations, photographs, and descriptions of themetal-clad switchgear

8. Troubleshooting Topics, Table D

C. CONFLICT WITH OTHER DOCUMENTS

This instruction bulletin is intended to assist the user insafety, usage, installation, operation, and maintenanceof the PowlVac® Metal-clad Switchgear. This instruc-tion bulletin covers the design common features of thePowlVac® Metal-clad Switchgear, and should be usedalong with other supplemental documents that pertainto the specific type of the metal-clad switchgear, andthe specific type of the circuit breaker purchased. Thisinstruction bulletin and any supplemental documentsmust be studied and understood in order for thepurchaser to become fully acquainted with the metal-clad switchgear.

THIS INSTRUCTION BULLETIN SHALL TAKEPRECEDENCE if a conflict exists between this instruc-tion bulletin and any other document, whether pro-duced by Powell Electrical Manufacturing Company orthe user, relating to safety, usage, description, installa-tion, illustration, maintenance, renewal parts, andprocedure.

D. OTHER ITEMS OF CAUTION

Before unpacking the metal-clad switchgear, study thisinstruction bulletin and all supplemental documenta-tion.

It should be noted that some illustrations containedherein are general illustrations showing componentlocations and may not represent the constructiondetails of each user’s specific equipment type andline-up.

To the extent required, the products described in thisinstruction bulletin meet all applicable ANSI, IEEE, andNEMA Standards; however, no assurance is given withrespect to local codes and ordinances because theyvary widely.

E. INSTRUCTION BULLETINS ON THE WEB

Powell Electrical Manufacturing Company InstructionBulletins are posted on the company Web site locatedat http://www.powellservice.com. The instructionbulletins are designed to provide our customers withtechnical information about our product and therecommended servicing, maintenance service adviso-ries, and renewal parts. For more information, pleasecontact Powell Apparatus Service Division (PASD) at1-800-480-PASD, 713-944-6900, [email protected].

II. SAFETY

Each user has the responsibility to instruct andsupervise all personnel associated with the installa-tion, operation, and maintenance of this equipment onall safety procedures which must be observed.Furthermore, each user has the responsibility ofdevising a complete safety program for each type orclass of equipment.

The metal-clad switchgear described in this instructionbulletin contains high energy and high speed mecha-nisms interlocked to provide specific operating se-quences. To insure the safety of personnel associatedwith installation, operation, and maintenance of the

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metal-clad switchgear, it is mandatory that the follow-ing rules be observed. These instructions are notintended to be a complete safety program, or to takethe place of the complete user safety program.Rather, these instructions cover the more importantaspects of personnel safety related to PowlVac® metal-clad switchgear.

A. GENERAL

1. Only supervised and qualified personnel trained inusage, installation, operation, and maintenance ofpower metal-clad switchgear shall be allowed towork on this equipment. It is mandatory that allrelated instruction bulletins, supplements, andservice advisories be studied, understood, andfollowed.

2. Maintenance programs must be consistent withthe customer’s experience and manufacturer’srecommendations, including service advisoriesand instruction bulletins. A well-planned andproperly executed routine maintenance program isessential for the metal-clad switchgear’s reliabilityand safety.

3. Service conditions and metal-clad switchgearapplications shall be considered in the develop-ment of such programs, including such variablesas ambient temperature and humidity, actualcontinuous current, thermal cycling, number ofoperations, interrupting duty, and unusual localconditions such as excessive dust, ash, corrosiveatmosphere, vermin, or insect problems.

B. SPECIFIC SAFETY RULES

1. DO NOT WORK ON AN ENERGIZED METAL-CLAD SWITCHGEAR. IF WORK MUST BEPERFORMED, THE POWER SUPPLY MUST BEDISCONNECTED AND DE-ENERGIZED, ANDTHE METAL-CLAD SWITCHGEAR MUST BEREMOVED FROM SERVICE BEFORE ANYWORK IS PERFORMED.

2. DO NOT WORK ON AN ENERGIZED CIRCUITBREAKER OR ON THE METAL-CLADSWITCHGEAR, REMOVE THE CIRCUITBREAKER FROM SERVICE AND REMOVE ITFROM THE METAL-CLAD SWITCHGEARENCLOSURE.

3. DO NOT WORK ON A CIRCUIT BREAKER WITHTHE CONTROL POWER ENERGIZED.

4. THESE CIRCUIT BREAKERS UTILIZE STOREDENERGY-SPRING CHARGED MECHANISMS.THESE MECHANISMS MUST BE SERVICEDONLY BY SKILLED AND KNOWLEDGEABLE

PERSONNEL CAPABLE OF RELEASING EACHSPRING LOAD IN A CONTROLLED MANNER.EXTREME CARE MUST BE EXERCISED TOKEEP ALL PERSONNEL, TOOLS, AND OTHEROBJECTS CLEAR OF MECHANISMS WHICHARE TO BE OPERATED OR RELEASED. DE-TAILED INFORMATION REGARDING THESEMECHANISMS IS FOUND IN THIS INSTRUC-TION BULLETIN, AND THE INSTRUCTIONBULLETIN FOR THE CIRCUIT BREAKER.

5. DO NOT ATTEMPT TO CLOSE THE CIRCUITBREAKER MANUALLY ON A LIVE CIRCUIT.

6. DO NOT USE AN OPEN CIRCUIT BREAKER BYITSELF AS THE SOLE MEANS OF ISOLATING AHIGH VOLTAGE CIRCUIT. FOR COMPLETEISOLATION, THE CIRCUIT BREAKER SHALL BEIN THE DISCONNECTED POSITION.

7. ALL COMPONENTS SHOULD BE DISCON-NECTED BY MEANS OF A VISIBLE BREAK ANDSHOULD BE SECURELY GROUNDED FOR THESAFETY OF PERSONNEL PERFORMINGMAINTENANCE OPERATIONS ON THE METAL-CLAD SWITCHGEAR, CIRCUIT BREAKERS, ORCONNECTED EQUIPMENT.

8. INTERLOCKS ARE PROVIDED TO INSURE THEPROPER OPERATING SEQUENCES OF THEMETAL-CLAD SWITCHGEAR, CIRCUITBREAKER, AND FOR THE SAFETY OF THEUSER. IF FOR ANY REASON AN INTERLOCKDOES NOT FUNCTION AS DESCRIBED, DONOT MAKE ANY ADJUSTMENTS, MODIFICA-TION, OR DEFORM THE PARTS. DO NOTFORCE THE DEVICE INTO POSITION. CON-TACT POWELL ELECTRICAL MANUFACTURINGCOMPANY.

C. X-RAYS

High test voltage that is applied across the contacts ofa vacuum interrupter may generate x-rays. Theintensity of this radiation is dependent on the peakvoltage and the contact gap. At the normal operatingvoltage of this equipment, the radiation levels arenegligible. At the voltages specified for testing, the testoperator shall be no closer than one meter in front ofthe circuit breaker, and shall be separated from thevacuum interrupters under test by the two thicknessesof steel used in the construction of the circuit breakerframe and the front cover. The circuit breaker shall beeither fully opened or fully closed when making highpotential test. Do not test the circuit breaker withcontacts partially opened.

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D. SAFETY LABELS

The metal-clad switchgear has danger, warning, andcaution labels attached to various locations. Read and

observe directions on all safety labels duringswitchgear operation, handling, and maintenance.

HAZARD OF ELECTRIC SHOCK OR BURNTURN OFF POWER TO THIS EQUIPMENT BEFORE

WORKING INSIDE.

WHEN CLEANING BUS BAR INSULATION,ONLY DENATURED ALCOHOL OR ISOPROPYLALCOHOL SHOULD BE USED TO REMOVEFOREIGN MATERIAL FROM THE INSULATIONSURFACE.

FAILURE TO DO SO MAY DAMAGE THEDIELECTRIC AND/OR THE MECHANICALPROPERTIES OF THE INSULATION!

HAZARDOUS VOLTAGEWILL CAUSE SERIOUS

INJURY OR DEATH.

DE-ENERGIZE ALL POWERBEFORE REMOVING BARRIERS.

REPLACE BARRIERSBEFORE ENERGIZING.

CONTROL AND INSTRUMENTPOWER MAY BE PRESENT

ON DEVICE STUDSAND TERMINAL BLOCKS

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Figure 1. Typical Metal-Clad Switchgear Line-up

III. DESCRIPTION

A. GENERAL

The P-51000 PowlVac® Metal-clad Switchgear withvacuum circuit breaker is designed to comply withANSI Standard C37.20.2 and the portions of NEMAStandard SG-5 applying to metal-clad switchgear.Metal-clad switchgear is characterized by removableinterrupting devices, isolation of major circuit elements,grounded metal compartments, and insulated primarybus conductors. The metal-clad switchgear is a line-upof one or more switchgear vertical sections known asunits, which are enclosed on all sides, top, and bottomexcept for the ventilation openings, lower unit cablepenetrations, and view windows.

The metal-clad switchgear is used to protect andcontrol medium-voltage/alternating current powerdistribution systems. Each unit consists of a numberof circuit breaker compartments, plus auxiliarycompartments containing accessory apparatus. Thecircuit breakers are used to control various types ofcircuits, such as incoming lines, bus ties, feeders,and motor starters. Also, special functions areprovided in great variety and may be required forparticular applications. Figure 1 illustrates a typicalPowlVac® metal-clad switchgear lineup.

This instruction bulletin should be used in conjunctionwith the appropriate instructions for Vacuum Circuit

Breakers, including any applicable supplement(s),separate instructions covering other components ofthe metal-clad switchgear, and applicable drawingsbecause each metal-clad switchgear line-up is customdesigned for a particular use and application. Sepa-rate instructions covering other components are notincluded in this publication, but are available uponrequest.

The PowlVac® Metal-clad switchgear basic verticalsections are available in two basic designs, one-highconstruction, and two-high construction.

1) One-high Construction

The basic one-high construction standard measure-ments are 92" height x 36" width x 83-5/8" depth. Thecompartment holds one circuit breaker. For specialuse, a one-high construction with extended height,front, center, and rear sections is available.

Figure 2. One-high Basic Construction

2) Two-high Construction

The two-high basic construction standard measure-ments are 95" height x 36" width x 95-1/8" depth. Thisconstruction can hold two circuit breakers: one in eachcompartment located one above the other.

Note: Each construction includes primary and sec-ondary compartments, as shown in Figure 2 and 3.These instructions apply to both types of construction.Where significant differences exist between the twoconstruction types, each is explained separately.

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C. PRIMARY COMPARTMENT

The primary compartment contains the highvoltage equipment and connections arranged incompartments to offer increased safety byminimizing personnel exposure and limiting theeffects of faults. The primary enclosure containscontrol devices, current transformers, shutters,interlocks, and a ground bus. See Figure 3 forthe location of the primary enclosure and seeFigure 4 for the equipment’s devices.

D. VOLTAGE RATINGS

PowlVac® Metal-Clad Switchgear is available inthe standard voltage ratings listed in Table 1.These ratings correspond to the ratings of thecircuit breaker used:

NOTE: Certain non-standard ratings are avail-able for special applications. Consult the manu-facturer for details. Refer to the specific jobdrawings for detailed voltage ratings applicable toparticular switchgear line-up.

E. LIGHTING IMPULSE WITHSTAND (BIL)

60 kV for 4.16 kV class switchgear;95 kV for 7.2 kV; and 13.8 kV class switchgear.

F. FACTORY DIELECTRIC TEST

Power Frequency Withstand (ANSI C37.20.2) is 19kVfor 4.16 kV class switchgear, and 36kV for 7.2 kV and13.8 kV class switchgear.

NOTE: If required, Field Dielectric Tests should belimited to 75% of Factory Dielectric Test values. Directcurrent dielectric testing is not recommended. If DCtesting is required, see Section V. OPERATION, B.TEST AND INSPECTION for values to be used.

B. SECONDARY COMPARTMENT

The secondary compartment (Figure 2) is located atthe front (circuit breaker withdrawal side) of theconstruction. It is a compartment with a hinged dooror panels, which is mounted with the necessaryinstruments, controls, and protective devices. Theterminal blocks, fuse blocks, and some control devicesare mounted inside the compartment on the sidesheets and barriers. A raceway is provided to carry thecontrol and instrumentation wiring between the com-partments near the top of all vertical sections and nearthe center of the two-high construction.

Figure 3. Two-high Basic Construction

Table A. PowlVac® Metal-clad Switchgear

Nominal Voltage

Class kV, rms

Nominal 3-Phase

MVA Class

K Factor 1 kA

Rated Continuous Current at

60 Hertz Amps, rms 4.16 250 36 1200, 2000, 3000 4.16 350 50 1200, 2000, 3000 7.2 500 50 1200, 2000, 3000

13.8 500 25 1200, 2000, 3000 13.8 750 36 1200, 2000, 3000 13.8 1000 50 1200, 2000, 3000 13.8 1500 63 1200, 2000, 3000

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2) Circuit Breaker Compartment SafetyProvisions

PowlVac® metal-clad switchgear is provided with apositive mechanical interlock, which is designed todeter moving a circuit breaker, except when theprimary contacts are open. It also deters closing theprimary contacts while the circuit breaker is beingmoved, by blocking the operating mechanism me-chanically and electrically.

Safety shutters open and close over the stationaryprimary disconnects devices in response to themovement of the circuit breaker racking Mechanism.A spring discharge interlock is provided to dischargethe main closing spring when a circuit breaker iswithdrawn from the compartment. This interlock isactivated by unplugging the secondary disconnect plug(Figure 4, k), or the secondary disconnect overridedevice accessory.

CAUTION

Before placing metal-clad switchgear with keyinterlocks in operation, the key scheme mustbe carefully checked and only the proper keysleft in the locks.

All extra keys must be removed and de-stroyed, or secured where they are accessibleonly in an Emergency.

G. CIRCUIT BREAKER: THE REMOVABLEELEMENT

PowlVac® metal-clad switchgear is designed to housedifferent types of removable elements for variousfunctions and operations. One of these elements isthe circuit breaker, which includes a stored energyoperating mechanism, interlocks, primary disconnectdevices, secondary disconnect devices, and a groundconnection. All circuit breakers are equipped withwheels for easy insertion into and removal from theswitchgear compartment. Refer to Figure 5 andFigure 6 for a brief description and illustration of theexterior features of the circuit breaker. All circuitbreakers furnished on a particular work order, and of alike design and rating are completely interchangeable.

For a detailed description of the circuit breaker and itsoperation, refer to the appropriate instruction bulletinand any applicable supplemental documents forPowlVac® Vacuum Circuit Breakers.

H. SAFETY INTERLOCKS AND PROVISIONS

WARNING AND CAUTION LABELS ARE LOCATEDIN VARIOUS PLACES IN AND ON THESWITCHGEAR AND ON THE CIRCUIT BREAKERREMOVABLE ELEMENT. ALWAYS OBSERVETHESE WARNINGS AND CAUTION LABELS. DONOT REMOVE OR DEFACE THESE WARNING ANDCAUTION LABELS.

1) Positions Interlocks

Position interlocks (Figure 4, b) are often supplied inconjunction with disconnecting switches, removableelements, and special compartments where access isdenied unless the removable element is withdrawn tothe test position. The operation of key interlockschemes is generally described by a note or key charton the work order drawings.

a. Mechanism-Operated Cell Switch (MOC)b. Position Interlocksc. Current Transformerd. MOC Operating Mechanisme. Breaker Enclosure Interference Platef. Floor Pang. Truck-Operated Cell Switch (TOC)h. Shuttersi. Shutter Operating Mechanismj. Ground Busk. Secondary Disconnect Plugl. Rollout Stop Block

Figure 4. Interior Metal-clad Switchgear(Lower Compartment)

j

g

h

l

i

k

a

f

b

c

d

e

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A breaker compartment interference plate(Figure 4, e) is provided, which is designed to hinderthe insertion of an incorrect type or rating circuitbreaker into the compartment. The breaker enclosureinterference plates for the metal-clad switchgear andthe circuit breaker are designed to allow a circuitbreaker with equal or higher voltage and currentratings to be inserted in the compartment, and tohinder insertion of a circuit breaker of a lower rating.

The circuit breaker rating should be checked againstthe metal-clad switchgear rating. Under no circum-stances shall the breaker compartment interferenceplate be removed. Removing this plate allows anincorrect type of rating circuit breaker to be inserted into the compartment. For safety and since the interfer-ence plate does not coordinate control wiring, ALWAYSREFER TO WORK ORDER INFORMATION, DRAW-INGS, AND SCHEMES TO MAKE CERTAIN THATTHE CIRCUIT BREAKER AND METAL-CLADSWITCHGEAR ARE COORDINATED FOR OPERA-TION.

A rollout stop block (Figure 4, l) is provided to deter theremoval of the circuit breaker from the compartmentuntil the rollout latch (Figure 6, o) on the circuit breakeris depressed.

I. CIRCUIT BREAKER RACKING MECHANISM

The circuit breaker racking mechanism enablesmoving the circuit breaker to one of three positions inthe secondary compartment of the switchgear: discon-nected, test, and connected.

1) Disconnected position

In the disconnect position, the movable primarydisconnects of the circuit breaker are disengaged andseparated at a safe distance from the stationaryprimary disconnects located in the compartment. Ametal shutter covers the openings of the stationaryprimary disconnect devices which prevents contact. Inthis position, the secondary disconnect devices andcontrol contacts are disengaged.

Figure 6. Front Description of Circuit Breaker

a. Padlock Provision Arm and Clipb. Manual Charging Crankc. Nameplated. Manual Trip Paddlee. Handlef. Breaker Position Indicatorg. Racking Shaft Shutterh. MOC Switch Operating Armi. Circuit Breaker Open/Close Indicatorj. Manual Close Paddlek. Operations Counterl. Spring Charge Indicatorm. Secondary Disconnect Receptaclen. Secondary Disconnect Guideo. Rollout Latch

Figure 5. PowlVac® Vacuum Circuit Breaker

h

lno

ij

m

k

feca b d g

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CAUTION

If the control circuits are energized, the springcharging motor will operate to charge the circuitbreaker’s main closing spring as soon as thesecondary disconnect plug is inserted into thesecondary disconnect receptacle.

CAUTION

If the circuit breaker main closing spring ischarged, withdrawing the secondary disconnectplug will cause this main closing spring to dis-charge.

2) Test Position

In the test position, the primary disconnect devices aredisengaged and the shutters are closed. The second-ary devices are completed, by plugging in the second-ary disconnect plug into secondary disconnect recep-tacle so that the breaker may be electrically or manu-ally operated. However, the circuit breaker is in thesame physical location as the disconnected position.

3) Connected Position

In the connected position, the movable primarydisconnects and stationary primary disconnects areengaged, the shutters are open, and the secondarydevices and control contacts are completed.

Interlocks deter the movement of a circuit breakerfrom one position to another, unless the circuit breakeris tripped open. The interlocks also deter closing thecircuit breaker between positions.

J. CIRCUIT BREAKER OPERATION

The circuit breaker is operated by a spring-storedenergy mechanism. A charging motor (Figure 7,e) isused to compress the main closing spring. During aclosing operation, the energy stored in the mainclosing spring is used to close the vacuum interruptercontacts, compress the contact loading springs,charge the opening springs, and overcome frictionalforces. When the circuit breaker is tripped, the energystored in the opening and contact loading springsopens the contacts at the correct speed. In an emer-gency the stored energy mechanism may be chargedby a manual charging handle.

The secondary disconnect plug (Figure 4, j) is anumbilical cord device. A multi-pin plug is located at theend of a cord attached to the right side sheet of thesecondary compartment. This plug must be insertedin the secondary disconnect receptacle (Figure 6, m) inthe circuit breaker before the circuit breaker can beplaced in a compartment rack. Once the plug isinserted, and the circuit breaker is racked past the testposition, the plug is held in place and cannot beremoved while the circuit breaker is in the connectedposition or when moving between the connected andtest position.

For complete instructions on inserting and withdrawingthe circuit breaker in and out of the metal-cladswitchgear, refer to the PowlVac® circuit breaker’sinstruction bulletin.

Figure 7. Circuit Breaker Cover Removed

a. MOC Switch Operating Armb. Opening Springc. Main Closing Springd. TOC Operating Pine. Charging Motor

a dcb

e

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K. AUXILIARY ENCLOSURES ANDCOMPARTMENTS

Many sizes of auxiliary enclosures and compartmentsare furnished for various purposes in PowlVac® Metal-clad Switchgear line-ups. Some are listed below:

1. Bus transitions to motor controllers

2. Bus transitions to transformers

3. Cable entrance compartments

4. Starting reactor or autotransformer compartments

5. Relay and metering compartments

6. Instrument transformer compartments

7. Control power transformer compartments

L. ANTI-CONDENSATION HEATERS

Anti-condensation heaters are provided in all outdoormetal-clad switchgear in order to facilitate drying andto prevent condensation. It is recommended thatheaters are energized at all times; accordingly, noswitch or thermostat is provided in the heater circuitunless specified. Each one-high basic construction isfurnished with a heater providing 125 watts of heat.Each two-high basic construction has two suchheaters, for a total of 250 watts of heat. See Figure 8.

Heaters in circuit breaker compartments are located atthe side of the secondary compartment, below thelower primary disconnect devices. Heaters in auxiliarycompartments are located in a similar location. Inauxiliary compartments equipped with rollouts, it maybe necessary to remove the lower rollout to gainaccess to the heater.

M. VOLTAGE (POTENTIAL) TRANSFORMER(ROLLOUT CARRIAGE)

The voltage transformers are mounted on a rolloutcarriage equipped with primary and secondary discon-necting devices. When the voltage transformers aredisconnected, they are at a safe striking distance fromall live parts of the metal-clad switchgear. In addition,a grounding device is provided which contacts thefuses when the voltage transformers are disconnected,effectively discharging the transformers. In thisposition, the transformer fuses may be safely removedand replaced. See Figure 9. When the voltagetransformer rollout tray is in the disconnected position,the rear barrier of the tray effectively deters access tothe stationary primary disconnects mounted in thecompartment behind the rollout tray. However, thesestationary primary disconnects may remain energized.

Figure 8. Unit Space Heater

a. Anti-Condensation SpaceHeaters

a

Figure 9. Voltage Transformer andRollout Carriage

a. Voltage Transformer (Potential)b. Rollout Carriagec. Fuses

a b c

N. FUSE DISCONNECTING DEVICE (ROLLOUTCARRIAGE)

Current limiting fuses with high interrupting rating aresometimes used in metal-clad switchgear to protectsmall transformers or circuits where circuit breakerscannot be economically or functionally justified.

13


O. CURRENT TRANSFORMERS(THROUGH-TYPE)

Ring-type current transformers (Figure 4, c) arepositioned around the stationary primary disconnectdevices. These current transformers are removablefrom the front and may be located on upper and/orlower primary disconnect supports. When necessary,special current transformers may be mounted in theline module.

CAUTION

Do not remove the rollout tray from its railswithout first deenergizing the primary circuitto which the rollout connects. Removing thetray makes the stationary primary disconnectdevices accessible.

WARNING

Before servicing or removing current trans-formers, de-energize the associated primarycircuits.

Figure 10. Control Power Transformer(Rollout Carriage)

When fuses are disconnected, they are at a safestriking distance from all live parts of the switchgear.In addition, a grounding device is provided whichcontacts the fuses after they are disconnected, effec-tively removing any static charge from the fuses. Inthis position, the fuses may be safely removed andreplaced. The disconnecting devices are capable ofinterrupting transformer magnetizing current, butshould not be used to interrupt load current. Mechani-cal or key interlocks are applied to prevent operatingthe disconnecting device while the load is connected.This is generally accomplished by interlocking so thatthe transformer secondary breaker must be locked inthe open position before the disconnecting device canbe opened or closed.

P. MAIN BUS, MAIN BUS TAPS, AND GROUNDS

The main bus, main bus taps, and ground bus conduc-tors are made of copper. The main bus, main busjoints, and taps are insulated. This insulation providesprotection against the propagation of arcing groundfaults, but does not offer personnel protection againstshock hazards. The bolted connections are silver-plated or tin-plated.

The main bus supports of a 15 kV class metal-cladswitchgear are of molded cycloaliphaticepoxy. The main bus supports of a 5 kV class metal-clad switchgear are of polyester glass laminate.

Q. PRIMARY DISCONNECT DEVICES ANDSUPPORTS

The primary disconnect devices have flat silver-platedcopper contact bars located within the molded cy-cloaliphatic epoxy supports. The rear of the contact isbolted to the main bus riser or to the line-side bus.The contacts may be withdrawn from the rear of thesupports when other bus connections have beenremoved.

a. Control Power Transformerb. Fusesc. Secondary Breaker Operating Handled. Manual Interlocke. “T” Handle

a b

c d e

The fuses are mounted on a rollout tray equipped withdisconnecting devices. Control power transformers of15 kVA and smaller may be mounted on the rolloutwith the fuses. See Figure 10.

14


The movable primary disconnects engage with thestationary primary disconnects in the primary compart-ment of the metal-clad switchgear. The removableelement disconnect contacts are self-aligned fingers,which will compensate for minor misalignment of up toapproximately 1/8 inch.

R. LIGHTING

For through-door and closed-door racking, all metal-clad switchgear are equipped with a 120 VAC interiorlight and a door-mounted light switch. When the light isswitched on, the user can read the circuit breakerposition indicator messages in the view window of thecompartment door. One of the following messagesappears: “breaker test/disconnected” or “breakerconnected.” See Figure 23 for an illustration of theinterior view light switch.

IV. INSTALLATION

For assistance with installation, maintenance, and forordering renewal parts, contact the Powell ApparatusService Division (PASD). Visit the Web site at: http://www.powellservice.com or call 1-800-480-PASD or713-944-6900.

Before placing the metal-clad switchgear with vacuumcircuit breaker into service, the purchaser must set orprogram components such as protective relays,meters, timers, etc., in accordance with the require-ments of the specific type of installation. Program-mable devices may be shipped with temporaryprogramming, which was used to test the metal-cladswitchgear. Electro-Mechanical relays may be shippedin a blocked position to avoid damage during ship-ment. Refer to the separate instructions for thesecomponents for information on applying settings orprogramming.

A. GENERAL

This section contains information on receiving, han-dling, positioning, power cable termination, grounding,and checks to make the equipment ready for opera-tion.

Once the assembly of the metal-clad switchgear iscompleted on site, all joints and hardware, includingbus connections, structural assemblies, and controlconnections, should be checked for tightness andproper torque values. See Table B, in Section J fortorque values.

B. RECEIVING

The PowlVac® Metal-clad switchgear is fabricated inrigid, floor-mounted self-supporting steel verticalsections. The switchgear vertical sections are shippedin an upright position and when received should bekept upright.

When the metal-clad switchgear line-up reaches itsdestination, the purchaser should check the materialreceived against the shipping list to be sure that allparts have been received. If damage is found orsuspected, file claims as soon as possible with thetransportation company and notify the nearest repre-sentative of Powell Electrical Manufacturing Company.

Refer to the instruction bulletin furnished for receiving,storage, and handling instructions on the circuitbreaker.

Some other components, such as top-mountedresistors or potential transformers, may be shippedseparately. These components are identified by anumber coinciding with that of the switchgear verticalsection on which they are to be mounted.

C. STORAGE

If it is necessary to store the metal-clad switchgearand equipment for any length of time, the followingprecautions should be taken to prevent corrosion:

1. Uncrate the switchgear and equipment and checkthe shipment for condition and completeness.

2. Store switchgear and equipment in a clean, dry(maximum 50% humidity) place with a moderatetemperature (15°C to 59°F) and cover with asuitable canvas to prevent deposit of dirt or otherforeign substances upon movable parts andelectrical contact surfaces.

3. Uncrate batteries and put on a trickle chargeimmediately on receipt.

4. If dampness or condensation may be present inthe storage location, heaters shall be placed insidethe units to prevent moisture damage. Approxi-mately 250 to 500 watts of heaters per unit will berequired. Remove all cartons and other miscella-neous material packed inside units before energiz-ing any heaters.

5. Removable elements, such as a circuitbreakers and ground and test devices should beprepared separately for storage. Refer to theapplicable instruction bulletin for each element forinstructions.

6. An indoor switchgear must not be stored outdoors,even if it is completely covered with tarpaulin orplastic sheet.

15


D. HANDLING

It is always preferable to handle a PowlVac® metal-cladswitchgear line-up with overhead cranes, by the liftingmeans provided. See Figure 11.

For an outdoor switchgear line-up, lifting channels areprovided and are attached to the base of the verticalsections. Spreaders should be used in the slingsabove the vertical sections to prevent damage to thetop edges of the switchgear. Do not attempt to lift theswitchgear by using the angles installed on the sides.The angles are provided only to tie the vertical sec-tions down during shipment, which insures that the unitwill not tip over if it is top-heavy. The angles are not tobe used for lifting purposes. Slings should be tied toreferenced angles to prevent equipment tipping.

If bases are furnished, the switchgear may be movedon an even surface by the use of rollers or heavy-dutypipes placed under the base. Any force to move orjack the switchgear must be applied to the base andnot to the switchgear. The use of a forklift truck is notrecommended, since the forks may damage thecompartments or interior parts of the switchgearvertical sections. If no other method of handling isavailable, the forks must go completely under theswitchgear base bottom to avoid damage to theswitchgear.

E. POSITIONING THE METAL-CLADSWITCHGEAR

The recommended aisle space for the front and at therear of the metal-clad switchgear is shown on the floorplan drawing furnished for the particular order. Thespace at the front must be sufficient to permit insertion,withdrawal, and transferring of circuit breakers. Thespace at the rear must be sufficient for installation ofcables, for inspection and maintenance, and on someswitchgear to roll out voltage or control power trans-formers. The dimensions shown on the switchgeardrawings are those required for proper operation of theswitchgear.

When three or more switchgear units are to be ar-ranged in one continuous line-up, THE CENTERSHIPPING UNIT SHOULD BE THE FIRST LOCATED.The other shipping line-ups should then be installed insuccessive order in each direction from the center ofthe structure.

When installing a unit substation or power center, thepower transformer and the adjacent metal-cladswitchgear line-up should first be lined up and set inposition in accordance with the dimensions on thebase plan drawing for the installation. The additionalunits should then be installed.

Establish a base line located a few inches in front ofthe units and parallel with the desired front of thestructure. Equalize the distances from the front of theunits to the base line to make the face of the groupparallel to the base line.

Additional shipping members may have been installedin the bus or primary area to insure against shippingdamage. All shipping members must be removedfrom the switchgear compartments. All joints must beproperly tightened and insulated before energizing thebus.

Mats, screens, railing, etc. that are external to metal-clad switchgear may be required to meet local code.These items must be provided by the purchaser.

Figure 11. Lifting Method for Switchgear

CAUTION

APPLICABLE NATIONAL OR LOCAL CODESOR REGULATIONS MAY REQUIRE GREATERAISLE SPACE THAN IS NEEDED FOR OPERA-TION OF THE METAL-CLAD SWITCHGEAR.IT IS THE PURCHASER’S RESPONSIBILITYTO COMPLY WITH THESE CODES ANDREGULATIONS.

1) Drawings and Diagrams

Before any installation work is done, consult and studyall drawings and the Bill of Materials furnished byPowell Electrical Manufacturing Company for theparticular order. The drawings include arrangementdrawings and wiring and schematic diagrams.

16


F. PREPARATION OF FLOOR-ANCHORING

1) Indoor Metal-clad Switchgear

The station floor must be strong enough to remain rigidand not sag under the weight of the switchgearstructure. The floor also must be able to withstand theimpact stress caused by the opening of the circuitbreakers under short-circuit conditions. The shortcircuit impact load is approximately 1-1/2 times thestatic load weight of the switchgear.

The purchaser must provide suitable means foranchoring the switchgear to the floor. The floorsupporting the switchgear must be level in order toavoid distorting the switchgear structure and to alignthe switchgear properly. The switchgear must becorrectly and completely aligned prior to applying finalanchors. Level foundations are desirable since theyautomatically produce true, level, and plumb switch-board installations. However, the switchgear willoperate satisfactorily on a true and flat foundation thathas a uniform slope of no more than 1/8 inch in threefeet. The switchgear units must be placed on the floorchannels in such a manner that the base of each unitrests directly on each of the floor channels. Therecommended floor construction is shown in Figure12.

The floor channels should have a minimum webdimension of 4 inches. The required quantity andlocation of the floor channels is shown on the drawingsfurnished with the order. The spacing of the floorchannels, including the center channel, must be asshown on the drawings. Even though the switchgearis not anchored to the center channel, its location isimportant to the proper support and alignment of theswitchgear units. The floor channels must be level and

straight with respect to each other. Brass shimsshould be placed under floor channels when leveling isneeded.

Care should be taken to provide a smooth, hard, andlevel floor underneath and in front of the units tofacilitate installation and removal of the circuit breaker.

When installing metal-clad switchgear on existingfloors, it will usually be desirable to pour a newlyfinished floor with embedded channels, or to cut slotsin the floor for embedding and leveling the supportingchannels.

Encircling loops of reinforcing or building steel aroundsingle-phase conductors should be avoided in theareas for main cables when these circuits are rated at600 amperes or above.

The recommended practice is to weld the switchgearstructure to the floor channels, using a tack weld atpoints indicated for anchoring on the drawing. Afterwelding, any damaged paint should be removed, andthe weld and surrounding metal should be painted todeter corrosion. If welding facilities are not available,the switchgear should be bolted to the floor channels.

2) Outdoor Metal-Clad Switchgear

Outdoor equipment is provided with a channel base,usually 6" high. The switchgear may be installed on aflat concrete pad or on continuous piers running thelength of the switchgear and located under the mainlongitudinal members of the base. If it is desired toinstall the switchgear on individual piers (not continu-ous for the length of the switchgear), consult with thefactory for recommendations on the locations of piers.

The foundation must be level in order to preventdistortion of the equipment. Poor outdoor foundation

Figure 12. Recommended Floor

17


• The space between adjacent doors should beequalized to permit their free swing and presenta neat appearance.

• The door stops permit a door swing of approxi-mately 150°.

2) Aligning Switchgear Doors

The switchgear doors may be raised or loweredvertically, moved to the left or to the right horizontally,or rotated to make them plumb.

To align doors perform the following steps:

1. Loosen the mounting screws which attach the doorto the movable half of the hinge assembly. Mount-ing screws are located on the inside of the door.

2. With the screws in place, align the door assemblyby repositioning the mounting screws in the slightlyoversized holes.

3. With the mounting screws in the aligned position,tighten the screws to the proper torque. SeeTable B.

4. If the doors require further alignment, additionaladjustments may be made to the stationary half ofthe hinge assembly, which is mounted by screws,located inside the flange of the switchgear sidesheet.

When properly aligned, the doors of outdoorswitchgear should be tightly seated on the gasket allaround the closure. After aligning doors, close andlatch the door and check the seal by inspecting thegasket for impression or by running a 3" x 5" cardaround the edge of the door. If the card passesbetween the door and the gasket, the door is improp-erly adjusted, and it should be readjusted until the cardcannot pass between the door and the gasket.

leveling may be corrected by inserting brass shims atthe points where the integral base frame is fastened tothe concrete foundation. Level foundations are desir-able since they automatically produce true, level, andplumb switchboard installations. However, theswitchgear will operate satisfactorily on a true and flatfoundation that has a uniform slope of no more than1/8 inch over a distance of 3 feet.

When installing switchgear units on foundations ofuniform slope, the floor of the units should be parallelto the foundation and the vertical center line of theunits should be perpendicular to the floor instead oflevel and plumb. For pad mounted switchgears, powerand control conduits should be installed prior to place-ment of the switchgear. For pier-mounted switchgear,the conduits may be installed either before or after theswitchgear is placed. The recommended method ofanchoring an outdoor switchgear is shown in Figure 13.

Grouting may be required to assure a good fit. Analternate method is to tack weld the channel base toleveling steel embedded in the concrete. It is notrecommended that users attempt to embed anchorbolts in the concrete to penetrate predrilled holes in thechannel base, as the accuracy required for this methodof anchoring is very difficult to achieve under fieldconditions. When outdoor switchgear is shipped inmore than one shipping sections, care must be takento weatherproof the shipping break.

The necessary gaskets, roof caps, trim pieces, andhardware are furnished with the switchgear. Thesemust be carefully installed and caulked. If main cablesenter at the bottom of any of the outdoor units, it will benecessary to remove the rear sheet and the rear floorsheet. As the bottom rear cable entrance compartmentwill then be completely open, the units may be movedover the projecting conduits.

G. DOOR ALIGNMENT

This section provides door alignment information incase it is necessary to realign the doors of metal-cladswitchgear during installation. Before aligning doors,ensure the switchgear is level and plumb as describedin Section IV, Installation. Starting at either end of theswitchgear lineup, realign each door individually asneeded.

1) Door Alignment Conditions

When aligning doors, the following conditions apply:

• The top of each door should be level with theadjacent doors.

• The sides of each door should be plumb.

• The surface of each door should be flush withadjacent doors.

Figure 13. Anchoring of Units with Channel Base

18

For anchor bolt locations see plandrawings furnished with equipment.

”J” Bolt


CAUTION

Before inserting a removable element into thecompartment, manually check the shuttermechanism, the mechanism-operated cellSwitch (MOC) (Figure 4, h) and operatingmechanism, and the truck-operated cell switch(TOC) (Figure 4, l) for free movement. Thesechecks shall be made with all circuits de-energized.

H. THE REMOVABLE ELEMENT

Before installing or operating a removable element,such as the circuit breaker, ground and test device, ordummy removable elements, consult the instructionsbulletin for directions on installation, maintenance, andrenewal parts for that particular element.

Removable elements located in the one-high construc-tion, or in the lower compartment of a two-high con-struction may be rolled into place into the switchgearvertical section from the floor. Removable elementslocated in the upper compartments of two-high con-struction must be lifted into place using the optional lifttruck or some other method of crane or hoist.

The recommended lifting procedure is describedunder Operation, in Section V. A . 1) of this instructionbulletin.

For a detailed description of the circuit breaker and itsoperation, maintenance, and renewal parts refer to theappropriate instruction bulletins for PowlVac® VacuumCircuit Breakers, and any applicable supplementaldocuments.

I. GROUNDING

Before power connections can be made, theswitchgear vertical sections must be grounded. Aground bus is furnished with lugs at each end forconnection to the station grounding system.

The ground bus is bolted to the rear of the verticalsection near the bottom. It is arranged so that con-nections to the station ground can be made in anyunit.

Where equipment is shipped in more than one group,the sections of ground bus must be connected byusing the splice plates furnished with the equipment.See Figure 14. Assemble the ground bus joints asoutlined under “Connections.” Ground bus connec-tions are made in the lower portion of the cableentrance compartment. The switchgear ground busmust be connected to the station ground bus by aconductor having a current carrying capacity equal tothat of the switchgear ground bus. It is very importantthat the equipment be adequately grounded to protectthe operator from injury when short circuits or otherabnormal occurrences take place and to insure that allparts of the equipment, other than live parts, are atground potential.

It is recommended that the connection to the stationground have a cross section of 500,000 circular mils(240 mm2) or greater if the soil in which it is buried is ofsuch character as to cause appreciable corrosion.This is especially true where electrolysis from straycurrents or contact with dissimilar metals exists. Theresistance of the soil surrounding a station grounddepends on the condition of the soil as well as itschemical content. Dry, loose, sandy or frozen soils willhave a high resistance as compared with moist soils orsoils containing ashes, cinders or salt solution. TheIEEE Standard 142 states that grounding impedance inthe range of 1 to 5 ohms is generally acceptable forindustrial substations. Ground resistance testing isrecommended to verify that the ground resistance fallswithin this range.

J. CONNECTIONS

The main bus bars and other connection bars arecopper. The connection surfaces are silver surfacedor equivalent. The silver plating used on boltedcontact surfaces is approximately 0.0001" thick; platingon sliding contact surfaces is thicker. All field as-sembled joints in primary conductors, regardless ofmethod of insulation, should be made as follows:

1. Wipe the surface clean with a lint-free cloth. Donot use sandpaper or any abrasive on the platedsurface. Avoid handling of cleaned surface asmuch as possible. If the surface is tarnished,clean it with silver polish and then wash it withdenatured alcohol.

2. Join the clean contact surfaces by using thehardware provided.

19


The correct length of bolt must be used in eachjoint to insure that electrical clearances at boltlocations are maintained. As a general rule, whenusing ½" diameter bolts, the bolt should be 1"longer than the combined thickness of the copperbars being bolted together.

For example, if three ¼"-thick copper bars are tobe connected, the bolt should be 1-3/4" long. Inaddition to proper length bolts, the bolt assemblymust include flat washers, split-ring lock washers,and nuts. All hardware must be SAE Grade 5 orbetter. See Figure 15 for the proper assembly ofhardware.

CAUTION

The operating temperature of conduc-tors in metal-clad switchgear mayreach 105°C. Any insulating materialused in the metal-clad switchgearmust be suitable for this temperature.

Figure 14. Ground Bus Splice Assembly CAUTION

ALL EXPOSED PRIMARY BUS ANDCABLE JOINTS AND CONNECTIONSMUST BE INSULATED FOR THECORRECT SYSTEM INSULATIONRATING.

K. MAIN BUS ASSEMBLY INSULATION

To insulate the main bus assembly, remove thecompartment covers. Then, bolt the splice plates andbus bars together, following assembly instructions asgiven under Section J. Connections. Tighten boltsproperly. See Table B.

Table B. Bolt Torque Values for PowlVac®

Metal-clad SwitchgearNOTE: The bolt head drawings in the following tableare not to scale. Locate the Bolting Torque label onequipment for an accurate drawing of bolt sizes.

3. In some cases, external connections are made tometal-clad switchgear bus by bars. The metal-clad switchgear bars are normally silvered plated.Unplated bars, either copper or aluminum shouldnot be used to connect to plated bars.

4. All field assembled primary conductor joints andterminations must be insulated for the operatingvoltage. There are two methods of insulatingjoints: taping joints or applying boots whereapplicable. A detailed procedure for joint insulationis described under Section K. Main Bus Assembly.

NOTE: All hardware must be tightened to thetorque values listed in Table B.

20

Figure 15. Proper Bolt Assembly


NOTE: The PVC insulation boots are furnished forstandard configurations. Special configurationconditions must be taped.

4. Replace all covers previously removed.

3) Cleaning Bus Insulation

The main bus bar is insulated with a high-temperaturethermoplastic or thermoset material that providesdielectric and mechanical properties. Clean theinsulation to provide optimum insulation properties.Only use denatured alcohol or isopropyl alcohol toclean the insulation.

Wear protective gloves and goggles and clean themain bus bar in a well-ventilated area.

Wipe dirt or other foreign matter from the insulationwith a clean cloth saturated with only denatured orisopropyl alcohol.

3 Layers 2/3 Lap, 15kV Tape Thickness x 92 Layers 2/3 Lap, 5 kV Tape Thickness x 6

Figure 16. Wrapping of Bus

To provide adequate bus joint insulation, use any ofthe following methods:

• Wrapping bus joints, using tape or heat shrinkmaterial

• Applying PVC (polyvinyl chloride) boots

1) Wrapping Bus Joint

1. Fill all cavities around the contact nuts and con-nection bars with the Solar Compounds Corpora-tion Solarite KM1592 compound. Form a smoothsurface for taping, thus preventing air voids.

NOTE: The compound is not an insulating me-dium and should not be used for that purpose.

2. Wrap the bus joint with 3 layers, 2/3 lap, of ScotchSuper 33+ black insulating tape, maintainingtension on the tape while wrapping. Where thereare sharp angles, apply additional layers to obtainthe equivalent of the insulation on the flat surfaces.

3. Over the black tape, apply 2 layers, 2/3 lap, ofScotch 35 red insulating tape.See Figure 16.

NOTE: One layer wound 2/3 lap requires 3 turnsaround bar in one width of the tape. One layerthickness is 3 times tape thickness.

2) Applying PVC Boots

1. Prepare all joints as outlined under Section J.Connections.

2. Place the PVC boot over the joint. The bootshould fit snugly around all conductors, andflanges must contact each other in a smooth joint.

3. Secure the boot with the furnished nylon wire ties.The joint insulation is now complete.

CAUTION

Use alcohol in a well-ventilated area to avoidinhaling vapors.

CAUTION

Do not use any commercial soap-based ordetergent-based cleaner because they maydamage the insulation material.

Do not use carbon tetrachloride.

Avoid prolonged exposure to solvent vapors.

Use solvents in a well-ventilated area.

L. PRIMARY CABLES

Access the primary cable connections in PowlVac®

Metal-Clad Switchgear by opening the hinged reardoors. Before any primary cable connections aremade, the cables should be identified to indicate theirphase relationship with the switchgear connections.This is necessary to insure that motors will rotate in theproper direction and that the phase rotation is thesame when interconnecting two different sources ofpower.

Normally, compression terminals are used to terminateprimary cables. When shielded cables are used,proper stress relief must be provided at the cabletermination. This may be done by the use of a com-mercially available cable terminator, many types of

21

P-51000 PowlVac® Metal-clad Switchgear IB-51000B.

which are available, or by the use of a stress cone,which can be either hand-built or the prepackagedtype. In all cases, carefully follow the cablemanufacturer’s recommendations for installation of thetype of cable being used. Normally, no insulation orstress relief materials are furnished for cable termina-tions.

Potheads may be used when it is desirable to hermeti-cally seal the end of the cable to make a moisture-proof connection between the cable and switchgearbus. A pothead also prevents seeping of oil from theend of oil impregnated varnish cambric or paperinsulated cable.

M. INSULATING PRIMARY CABLESTERMINATIONS

All field assembled joints for primary cable termina-tions should be prepared as outlined under Section J.Connections. Upon completion of the cable termina-tion, care must be exercised when taping the exposedtermination.

1. All taping of roof bushing should be insulated asoutlined in Figure 17.

through the transformer. Armor clamps are furnishedfor this purpose when specified.

When lead or other conducting sheath cable, or cablewith shielding tape or braid is used, it is recommendedthat the sheath or shield be grounded solidly to theswitchgear ground bus. The ground lead should bebonded to the sheath or shield on the side of thecurrent transformer away from the primary terminals.In cases where the ground cannot be applied beforethe cable passes through the transformer, bond thelead to the sheath or shield between the transformerand the primary terminals. The ground conductormust then be passed back along the cable paththrough the current transformer before being con-nected to the ground bus.

Where potheads are used in the units provided withground fault current transformers, the potheadmountings must be insulated from ground. All cablesshould be kept as close to the center of the currenttransformer window as possible.

Figure 18. Rear View of Two-High Unit andGround Fault Transformer

a. Busesb. Ground Fault Transformer

b

b

a

a

Figure 17. Taping of Roof Bushing

2. The instructions for application of the tape insula-tion are the same as outlined for wrapping ofjoints.

N. GROUND FAULT CURRENT TRANSFORMERS(THROUGH TYPE)

Through-type current transformers are furnishedwhere specified for sensitive protection against groundfaults. These transformers are normally installed in ahorizontal position directly above or below the primarycable terminals, so that the primary cable or cablescan pass through them. One transformer is requiredfor each three-phase circuit. See Figure 18.

Where armored cable is used, the armor must beterminated and grounded before the cable passes

22


O. CONTROL CABLES

When control conduits enter the unit from below, theconduit should not extend more than 1 inch above thefloor. The control cables may be pulled through theconduits before or after the switchgear is installed,whichever is more convenient.

If the control conduits enter from above, drill the topcover of the front enclosure to suit the conduits, beingcareful not to damage existing wire bundles. Fastenthe conduits to the cover with locknuts.

Connect the cables to the terminal blocks in accor-dance with the wiring diagrams furnished for thespecific job. Control cables that must pass throughany primary enclosure must be routed in the metal-enclosed wireways provided within the switchgear, andall wireway covers must be replaced.

The cables from the control power source to theswitchgear must be large enough to avoid excessivevoltage drop when the circuit breakers are operated.(See testing instructions that apply to a particulardevice.) Where units have been split for shipment,any control or other secondary leads that must connectacross the split will be arranged with terminal blocks ina convenient location so that the wires can be recon-nected. The wires will be cut to length and formedbefore being folded back so that a minimum time willbe required for reconnecting them.

P. SURGE PROTECTOR

It is the responsibility of the purchaser to providesuitable surge arrestors to protect the metal-cladswitchgear from damage due to lightening or otherelectrical surges. When surge arrestors are furnishedas part of the switchgear, the primary cable terminationis insulated at the factory unless it must be discon-nected for shipment. When this connection is com-pleted in the field, it is necessary to insulate theprimary connection before the switchgear is energized.Normally, PVC boots are supplied to insulate theseconnections.

Q. ROOF ENTRANCE BUSHING

When furnished, roof entrance bushings are frequentlyremoved from the metal-clad switchgear for shipment,and the mounting openings are covered with shippingcovers.

To install the roof entrance bushings, remove anddiscard the shipping covers and install the roof en-trance bushings in their place. Use the gasket materi-als furnished with the roof entrance bushings to insurea weatherproof installation. If the bushings have fixedterminals, which cannot be rotated in the field, be sure

that the bushing terminal is aligned properly beforebolting the bushing in place.

When assembling the connection bar end of the roofentrance bushings inside of the metal-clad switchgearand other terminations where porcelain insulators areused, insulation should be applied as follows:

1. Prepare the connection bars as outlined underSection J. Connections. Fill all cavities around thecontact nuts and connection bars with SolariteKM1592 compound. Form a smooth surface fortaping, thus preventing air voids.

NOTE: The compound is not an insulating me-dium and should not be used for that purpose.

2. Wrap joint with insulating tape provided, maintain-ing tension on the tape while wrapping as shown inFigures 16 and 18. Where there are sharp angles,apply additional layers of tape to obtain the equiva-lent of the insulation on the flat surfaces.

R. VOLTAGE TRANSFORMER (VT), CONTROLPOWER TRANSFORMER (CPT), AND FUSEROLLOUT CARRIAGES

Rollout carriages will be shipped in a slightly openposition, which are held in place by two angle shippingbrackets bolted to the left and right support plates.Remove and discard the brackets and the hardware,which are used to attach them to the support plates.See Figure 19.

Close the rollout carriage carefully, insuring that theprimary and secondary disconnect devices alignproperly, and that the carriage closes completely. Also,confirm the operation of the interlocks provided withcontrol the power transformer and fuse rollouts. Therollouts function as follows:

a

Figure 19. Angle Shipping Bracket

a. Angle Shipping Bracket

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1) Control Power Transformer Rollout

The secondary circuit breaker is mounted inside thefront cover of the rollout, with its operating handleprojecting through the cover. The interlock mecha-nism deters opening or closing of the rollout carriageunless the secondary circuit breaker is in the “off”position.

To close the carriage, operate the secondary circuitbreaker to the “off” position, lower the interlock slider,and turn the “T” handle counterclockwise. It shouldnot be possible to close the secondary circuit breakerwith the interlock in this position. Close the carriage ina smooth but brisk motion, and turn the “T” handleclockwise raising the interlock slider, and operate thesecondary circuit breaker to the “on” position. With theinterlock in this position, it should not be possible toturn the “T” handle counterclockwise far enough tounlatch the carriage, or to roll out the carriage. SeeFigure 10.

To open the carriage, reverse the above procedure,withdrawing the carriage in a smooth but brisk motion,to prevent arching between the contacts.

2) Fuse Rollout

Fuse rollouts are normally interlocked with the second-ary circuit breaker of the transformer that the fusesprotect, using a key interlock system. The secondarycircuit breaker is provided with a key interlock whichreleases a key only when the circuit breaker is lockedin the “off” position. The rollout carriage is providedwith a key interlock, which deters opening or closing ofthe carriage unless the key is retained and the bolt iswithdrawn.

V. OPERATION

A. GENERAL

All removable elements, such as the circuit breakers ofthe same type, rating, and duplicate wiring may beinterchanged.

During operation, all live parts are enclosed by barrierswhich permits the user to perform maintenance withmaximum safety. Separate covers are provided overeach different compartment, so that any compartmentof housing may be exposed without exposing othercompartments.

All PowlVac® vacuum circuit breakers are equipped forelectrical operation. A manual charging handle issupplied as part of the accessories to permit manualoperation of the circuit breaker during maintenance.

“THIS DEVICE MUST NOT BE USED TO CLOSETHE CIRCUIT BREAKER ON ANY ENERGIZEDCIRCUIT.”

The control circuits may be checked accurately andsafely by moving the circuit breaker to the test positionwhere the main circuits are disconnected and thecontrol circuits are completed.

1) Inserting the Circuit Breaker into theCompartment

Do not place the circuit breaker into the compartmentuntil the switchgear line-up installation is complete. Ifthe circuit breakers are placed into the switchgear line-up before the installation is complete, trouble mayoccur from foreign materials in the compartments, andfrom a non-level foundation, or from distortion causedduring shipment or handling.

The circuit breaker can be inserted into the lowercompartment of the switchgear unit by first aligning thecircuit breaker wheels with the compartment floor panchannels. The circuit breaker is now ready to beinserted into the test position, and then racked to theconnected position. This procedure is fully describedin the circuit breaker instruction bulletin.

The procedure for inserting a circuit breaker into theupper compartment of a two-high construction varies,because the procedure depends on the design of thelift truck that shall be used.

The standard lift truck is used when adequate aislespace (68" minimum) is available. Perform thefollowing steps to insert a circuit breaker in the uppercompartment:

1. Lower the lift truck tray to the lowest position andset the brake (Figure 21, a).

2. While holding the lift truck in place, roll the circuitbreaker onto the tray, so that the front cover ofcircuit breaker faces towards the lift mechanism ofthe truck (Figure 21, b).

3. Push the circuit breaker onto the tray until thecircuit breaker latches onto the tray(Figure 21, c).

4. Open the upper compartment door of theswitchgear unit.

5. Release the brake and roll the lift truck to theposition in front of the lower compartment(Figure 21, d).

6. Elevate the circuit breaker slightly above the uppercompartment track level.

7. Position the lift truck tray onto the track level, sothat the slots at the edge of the tray will engagethe hooks in upper compartment (Figure 21, e).

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8. Lower the circuit breaker until the tray latches tothe compartment (Figure 21, f) floor pan, and setthe brake.

9. Release the circuit breaker rollout latch from theslot of the tray, and roll the circuit breaker into thecompartment until the rollout latch engages therollout stop block in compartment (Figure 21, f).

10. Disengage and remove the lift truck once thecircuit breaker is completely secured in the com-partment.

For removal of the circuit breaker, see Section 2),Removing a Circuit Breaker from the Upper Compart-ment.

NOTE: An alternate lift truck may be used for aswitchgear line-up that has an aisle space as narrowas 60 inches.

7. Disengage and remove the lift truck once thecircuit breaker is completely secured in the tray.

8. Lower the lift truck tray to the lowest position andset the brake.

9. While holding the lift truck in place, roll the circuitbreaker off of the tray.

3) Electrical Operation

1. General: A one-line, or three-line diagram, and aschematic diagram are prepared for each metal-clad switchgear line-up. All diagrams shall bethoroughly studied and completely understood bythe user before the metal-clad switchgear is placedinto service.

2. The reading of indicating, recording instruments,and meters is common knowledge to electricallytrained personnel. The use of instrument, rheostatcontrol, and governor motor control switches arealso common. Synchronizing switches are usuallyprovided on generator and incoming line units witha synchronizing switch contact, which is wired inseries with the circuit breaker control switch “close”contact. The synchronizing switch should alwaysbe turned “on” first, and the circuits adjustedshould be in synchronism as indicated by thesynchroscope before the circuit breaker is closed.

3. A green light indicates that the circuit breaker isopen, and a red light indicates that the circuitbreaker is closed. For the DC control schemes,the red light is also arranged to supervise the tripcoil and indicate that the trip coil circuit has conti-nuity.

4) Shutters

Metal shutters (Figure 20, a) cover the primary discon-nect contacts when the removable element is with-drawn from the compartment.

CAUTION

This is a two (2) person job. Do not attempt toperform this procedure alone, as it may resultin injury to the user, damage to the circuitbreaker, or damage to the lift truck.

CAUTION

When removing the circuit breaker from the lifttruck, hold the lift truck firmly in place toprevent the truck from rolling away from thecircuit breaker.

2) Removing a Circuit Breaker from the UpperCompartment

1. Release the brake and roll the lift truck to theposition in front of the lower compartment.

2. Open the upper compartment door of theswitchgear unit.

3. Elevate the lift truck slightly above the uppercompartment track level.

4. Position the lift truck tray onto the track level, sothat the slots at the edge of the tray will engagethe hooks in the upper compartment.

5. Lower the lift truck until the tray latches to thecompartment floor pan, and set the brake.

6. Release the circuit breaker rollout latch and roll thecircuit breaker into the lift truck tray until the rolloutlatch engages the tray.

a aFigure 20. Shutters

a. Shutters

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Figure 21. Recommended Method for Lifting Circuit Breaker To Upper Cell

f. Circuit Breaker Rolled into the Compartmentc. Circuit Breaker Latched in the Lift Truck Tray

e. Circuit Breaker Approaching Hookb. Circuit Breaker Placed on the Lift Truck

d. Lift Truck and Switchgear Position a. Lift Truck Ready to Receive the Circuit Breaker

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Cam plates (Figure 25, d) located on each side of thecompartment are operated by the circuit breaker crankarm rollers, which will then operate the switchgearshutters. As the circuit breaker is operated past thedisconnected position, the crank arm rollers will movethe cam plates rearward, and open the shutters beforethe circuit breaker starts its forward travel to the con-nected position. When the circuit breaker is racked tothe disconnected position, the shutters are returned totheir closed position by springs attached to the camplates. Provisions for padlocking the shutters in theclosed position are furnished on each of the two camplates. Padlocking either of the two cam plates willdeter opening of the shutters.

5) Racking Mechanism

The racking mechanism consists of two slotted camplates mounted on each side of the compartment(Figure 25, c) and the racking mechanism on thecircuit breaker. The crank arm rollers at the ends ofthe racking crank arms of the circuit breaker willengage the cam plates in the compartment, and theact of moving the circuit breaker from one position toanother can be performed. The procedures that movesthe circuit breaker from one position to another areknown as “standard racking,” “closed door racking,”“through door racking,” and “power racking.” Closed-door racking, through door racking, and power rackingare the three optional methods for racking the circuitbreaker into the compartment. All three rackingmethods incorporate a torque limiting device whichprevents damage to the racking mechanism. Refer toappropriate instructions for PowlVac® Vacuum CircuitBreakers, including any applicable supplement(s), fora further description of the full operating instructionsfor this racking mechanism.

With the three optional methods of racking, the frontdoor of the compartment has an opening, whichenables the racking procedure to be performed. Thisopening is covered by a teardrop cover which auto-matically closes by gravity when the racking handle isremoved. The metal-clad switchgear door is alsoprovided with other options, such as a viewing window,and an internal light which will allow viewing thebreaker position indicator (Figure 6, f) located on thecircuit breaker to be viewed. See Figure 22.

CAUTION

Before inserting the circuit breaker into thecompartment, be sure that the racking crankarms of the circuit breaker are in the fullywithdrawn position, pointing towards themovable primary disconnects. Otherwise, theprimary disconnects, shutters, or the rackingmechanisms may be damaged.

CAUTION

Before attempting to rack a circuit breaker in orout of compartment, make sure that the keyinterlock is unlocked and in the opened posi-tion. Otherwise, the racking mechanism may bedamaged.

Figure 22. Closed Door Racking

A further option to closed door racking is closed doortripping. If this option is furnished, a mechanical tripbutton on the door operates a mechanism within thecompartment, which trips the removable element.

6) Floor Pan

Each compartment is equipped with a floor pan (Figure4, f), which the removable element rolls on. Each sideof the pan is designed with channels, which the wheelsof the removable element roll into. The width betweenthe channels will align the removable element laterallyas it is rolled in the compartment.

The top flanges of the channel deter any tipping orvertical movement of the removable element. A rolloutstop block is welded to the top of the right channel ofthe floor pan. When a removable element is rolled intothe compartment, the rollout latch on the lower rightside of the removable element will drop behind thisrollout stop block. The latch deters the removal of theremovable element until the latch is manually de-pressed.

7) Truck-Operated Cell Switch (TOC) (Optional)

The purpose of the truck-operated cell switch (TOC) isto indicate whether or not the removable element is inthe connected position. (See Figure 4, g.) Whenrequired, the switch is mounted in the upper right

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fg

i

h

a b c

d

e

d

CAUTION

BEFORE ATTEMPTING TO RACK A REMOV-ABLE ELEMENT IN OR OUT OF A COMPART-MENT EQUIPPED WITH A REMOVABLE ELE-MENT KEY INTERLOCK, MAKE SURE THATTHE INTERLOCK HAS BEEN UNLOCKED ANDIS IN THE OPEN POSITION. OTHERWISE, THERACKING MECHANISM MAY BE DAMAGED.

corner in the secondary compartment. A TOC operat-ing pin (Figure 7, d) mounted on the upper right cornerof the removable element, just behind the front cover,engages the operating arm of the TOC switch andoperates the switch as the removable element movesfrom the test position to the connected position. Whenthe removable element is withdrawn, the spring returnmechanism of the switch returns to its original position.

8) Removable Element Position Interlock(Optional)

The removable element position interlock is a me-chanical, manually operated assembly designed todeter movement of the removable element from oneposition to another. The interlock may be securedeither by padlocks, or by key interlocks. The interlockconsists of an L-shaped steel bar with support brack-ets, and lock provisions. (See Figure 24.)

The interlock is held by gravity in the open, or non-interlock position. When the removable element is outof the compartment, rotating the interlock 90° clock-wise, and securing it will block the insertion of aremovable element. The L-shaped bar of the keyinterlock is attached to a steel plate which blocksmovement of the removable element. There are twovarieties of the steel plate. When the first variety isused, it blocks the operation of the key interlock whena removable element is in the connected position.This prevents locking the removable element in theconnected position, giving the interlock a “lock outonly” function. The second variety of steel plateenables the interlock to be operated with the remov-able element in either in the connected or discon-nected position, which gives the interlock a “lock in andout” function.

9) Mechanism-Operated Cell Switch (MOC)(Optional)

The mechanism-operated cell switch (MOC) is anauxiliary switch operated by linkages in the compart-ment, which operates in conjunction with the circuitbreaker mechanism.

a b

Figure 23. Typical Compartment Door

Figure 24. Position Interlock

a. Position Interlockb. Compartment

a. Breaker Open Light (Green)b. Breaker Main Spring Charged Light (White)c. Breaker Closed Light (Red)d. Door Handlee. Teardropf. View Windowg. Compartment Doorh. Interior View Light Switchi. Breaker Control Switch

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The MOC switch operating arm, which projects fromthe jackshaft of the circuit breaker at the lower left sideof the circuit breaker, operates in conjunction with theMOC assembly. This arm rides over an angle pivotedon the lower left side sheet of the compartment. Whenthe circuit breaker is closed, the arm moves down-ward, deflecting the angle.

A linkage to the switch connects the angle, and thewhole assembly is spring-loaded to the open position.In the one-high basic construction and in the lowercompartments of the two-high basic construction, theswitch is mounted in the compartment near the upperleft corner, and the operating linkage extends down-ward to the pivoted angle. In the upper compartmentsof the two-high construction, the switch is mountedbelow the left side of the circuit breaker, and theoperating linkage extends upward to the pivoted angle.See Figure 25 and Figure 26. As supplied, the mecha-nism-operated cell switch (MOC) will operate with theremovable element in either the connected or the testposition. If it is desired that the switch operate in theconnected position only, remove the small bolted-onangle that forms the bottom flange at the front of thepivoted angle.

10) Secondary Disconnect Device

The metal-clad switchgear has a secondary discon-nect device, which is a 16-point plug mounted at thelower end of an umbilical cord, which hangs at the rightside of the compartment. The secondary disconnectplug (Figure 4, k) plugs into the secondary disconnectreceptacle (Figure 6, m) on the lower right front of thecircuit breaker.

Interlocks are provided to deter misoperation of thecircuit breaker. Interlocks function as follows:

1. The secondary disconnect plug must be insertedinto the secondary disconnect receptacle when thecircuit breaker is in the disconnect position in orderto rack the circuit breaker from the test position.

2. The secondary disconnect plug must be insertedinto the secondary disconnect receptacle tooperate the circuit breaker in the test position.

3. The secondary disconnect plug may be withdrawnwith the circuit breaker in the test position, bydepressing the secondary disconnect guide, whichholds the plug in place, and pulling straight out onthe plug’s handle to disconnect the secondarydisconnect plug. The circuit breaker cannot beoperated or racked in either direction with the plugwithdrawn. Removing the plug will open a closedcircuit breaker and discharge the closing spring if itis charged.

Figure 25. Lower Mechanism-Operated Cell

Switch (MOC) and Operating Mechanism

a. Mechanism-Operated Cell Switch (MOC)b. MOC Operating Linkagec. Cam Plated. Shutter Operating Cam Platee. Pivoted MOC Operating Anglef. Bolted-on Angle

Figure 26. Upper Mechanism-Operated Cell

Switch (MOC) and Operating Mechanism

a. Mechanism-Operated Cell Switch (MOC)b. MOC Operating Linkagec. Cam Plated. Shutter Operating Cam Platee. Pivoted MOC Operating Anglef. Bolted-on Angle

ef

b

a

d

c

f

b

e

c

a

d

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CAUTION

UNDER NO CONDITIONS MUST THE DUMMYREMOVABLE ELEMENT BE RACKED IN OROUT WHEN THE BUS OR UNIT IS ENERGIZED.

4. The secondary disconnect devices must becompleted to enable the act of racking the circuitbreaker between the test position and the con-nected position. During this act, the plug is heldcaptive and cannot be withdrawn until the circuitbreaker returns to the test position or the connectposition.

11) Dummy Removable Element

Dummy removable elements are used as a means ofisolating circuits or bus sections, where operation isinfrequent and a circuit breaker cannot be economi-cally justified. The element consists of a framework,and primary disconnects which simulates the circuitbreaker removable element. The front ends of theprimary disconnects are connected, top to bottom, bycopper bars, which are fully isolated. The stationarystructure is the same as for the circuit breaker, exceptthat no secondary disconnect device or control devicesare provided. When the element is racked intoposition, it connects the upper set of the metal-cladswitchgear primary disconnect devices to the lowerset.

Key interlocks are applied to insure that all source ofpower is disconnected before operating the dummyremovable element. The key interlock used is similarto that described in the “Operation” section above, andis set up for the “Lock in and out” mode of operation.

The interference plates provided on the dummyremovable element will deter the insertion of anelement of lower continuous current rating in a higher-rated compartment. Further, these plates deter theinsertion of any dummy removable element into anycircuit breaker compartment. It may be possible toinsert a circuit breaker removable element into adummy removable compartment as far as the discon-nect position, but it cannot be racked into the compart-ment because there is no secondary disconnectdevices to perform the necessary interlock functions.

12) Ground and Test Device

The PowlVac® ground and test device is a removableelement which is mounted on a frame similar to theframe of a circuit breaker. It is equipped with aground contact, primary disconnects, groundingcables, test ports, wheels, and can be operatedmanually or electrically.

The ground and test device provides a means forobtaining access to the primary disconnect devices ofthe circuit breaker compartment for the purpose ofgrounding the primary circuits, and conducting certainhigh voltage withstand tests (hipot). Insulation andisolation barriers between phases, and between phaseand ground are also provided where required.

B. TEST AND INSPECTION

For test and inspection instructions, refer to applicableinstruction bulletins and any supplemental documents.For assistance with testing and inspection, contact thePowell Apparatus Service Division (PASD) on our Website at http://ww.powellservice.com, or call 1-800-480-PASD or 713-944-6900.

After the equipment has been installed and all connec-tions made, it should be tested and inspected beforeputting in service. Although the equipment anddevices have been completely tested at the factory, afinal field test should be made to be sure that theequipment has been properly installed and that allconnections are correct and have not become loose intransportation. The primary equipment should becompletely de-energized while the tests are inprogress.

The directions for testing devices such as relays,instruments, and meters are given in the instructionbook furnished for each device. The settings of theprotective relays must be coordinated with the otherrelays on the system and, therefore, these relays mustbe set by the purchases. General instruction booksare furnished for complicated automatic equipments,describing the sequence of operation of the devicesrequired to perform the desired function.

When transformers are furnished to supply the controlpower, the primary taps should be selected so that thecontrol voltage indicated on the wiring diagram isobtained on the secondary of the transformer. When abattery is used to supply the control power, the cablesfrom the battery to the switchgear should be largeenough to avoid excessive voltage drop. The voltageat the terminals of the breaker closing coils, when thebreaker is being closed, should not be less than 43.2volts for 48 volt coils, 112.5 volts for 125 volt coils, or225 volts for 250 volt coils.

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Make a rough check of engagement between allmoving and stationary contacts in both the connectedand disconnected (or grounded) positions. Thiscontact engagement may be checked simply by“lighting-out” or ringing-out” with a flashlight or bell.Contact engagement is factory adjusted and undernormal circumstances will check out properly.

After the switchgear together with the apparatus whichit is to control has been installed and all interconnec-tions made, it should be given a final check and testbefore being put into service. Extreme care must beexercised to prevent the equipment to be controlledfrom being connected to the system while the prelimi-nary tests are being conducted.

The testing equipment will depend on the size and typeof installation. Portable voltmeters will be required.For large and complicated installations, ammetersshould be available in case unexpected troubledevelops. Some simple portable device for “ringing” or“lighting-out” circuits should be included in the testingequipment.

WIRE CONNECTIONS, ACCESSIBLE BOLTED BUSCONNECTIONS, AND INSULATED JOINTS SHOULDBE EXAMINED TO MAKE SURE THAT THEY HAVENOT BEEN LOOSENED OR DAMAGED DURINGTHE SHIPMENT OR INSTALLATION.

The connections to the equipment apart from theswitchgear, such as instrument transformers, remotecontrol and interlock circuits, and auxiliary switchesshould be “lighted out” to make sure that they are alsocorrect. The extent to which this will have to be donedepends on the thoroughness of the installation work.There must be definite assurance that connections arecorrect before an attempt is made to operate theequipment.

The covers for meters, relays, and other devices whichhave to be removed during the course of installationand test should be carefully handled when removed.The covers should be put back in place promptly tokeep dust and dirt from collecting on the vital relayparts.

After the switchgear has been installed and put intooperation, the drawings supplied with the equipmentshould be reviewed and any deviations made duringthe installation should be noted.

NOTE: Exercise extreme care to ensure that equip-ment, which is to be supplied by the switchgear, is notconnected while preliminary tests are conducted.

As a final check before energizing the equipment, theinsulation integrity of the high voltage circuits shouldbe verified with a high voltage (2,500V or greater)megohmeter. All portions of the high voltage circuitsshould be checked, both phase-to-phase and phase-to-ground. This check will verify that there is no majorinsulation damage due to shipping, handling, andinstallation.

If a more stringent test of insulation integrity is desired,an AC high potential test is recommended. Performthe one minute low frequency withstand test describedin ANSI Standard C37.20.2- 1999 Subclause 5 and 6,at the voltage level appropriate for the equipment,14kV for equipment rated 4.16kV or 27kV for equip-ment rated 7.2kV or 13.8kV. Notice that these valuesare 75% of the factory high potential test values.

The covers for meters, relays, and other devices thathave been removed during the course of installationand tests should be carefully handled when removed.The covers should be put back in place promptly tokeep dust and dirt from collecting on the vital relayparts.

After the metal-clad switchgear has been installed, andput into operation, the drawings supplied with theswitchgear line-up should be studied and reviewed,and compared to any notations made on them of anydeviation made during or before time of installation.

For assistance contact the Powell Apparatus ServiceDivision (PASD). Visit the Web site at http://www.powellservice.com, or call 1-800-480-PASD or713-944-6900.

CAUTION

DC high potential testing is not recommended;however, if it is required, the voltage levelappropriate for the equipment, must be used.These are 20 kV for equipment rated 4.16 kV or38 kV for equipment rated 7.2 kV or 13.8 kV.The DC high potential test machine must notproduce instantaneous peak voltages exceed-ing 50 kV. For further information on DC highpotential testing, refer to the separate instruc-tions for PowlVac® Circuit Breakers.

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VI. MAINTENANCE

Contact Powell Apparatus Service Division (PASD) forassistance in performing maintenance, or for settingup a maintenance program. Visit the Web site athttp://www.powellservice.com, or call 1-800-480-PASDor 713-944-6900.

A regular maintenance schedule should be establishedto obtain the best service and reliability from theswitchgear. Plant operating and local conditions willdictate the frequency of inspection required. Forspecific information regarding the maintenance ofdevices, such as circuit breakers, relays, meters, etc.,refer to the separate instruction book furnished foreach device. The inspection cabinet, when furnished,provides a convenient means for maintaining thecircuit breakers. Under normal conditions, the protec-tive relays do not operate, therefore, it is important tocheck the operation of these devices regularly.

A permanent record of all maintenance work should bekept, the degree of detail needed depends on theoperating conditions. In any event, it will be valuablereference for subsequent maintenance work and forstation operation. It is recommended that the recordinclude reports of tests made, the condition of equip-ment, and repairs and adjustments that were made.

BEFORE ANY COVERS ARE REMOVED OR ANYDOORS OPENED WHICH PERMIT ACCESS TO THEPRIMARY CIRCUITS, IT IS ESSENTIAL THAT THECIRCUIT OR CIRCUITS BE DE-ENERGIZED ANDBREAKERS BE WITHDRAWN TO A DISCON-NECTED POSITION AND TAGGED OR LOCKEDOUT.

IF WORK IS TO BE DONE ON A REMOTE EQUIP-MENT CONNECTED TO A UNIT, THE BREAKERFOR THAT UNIT SHOULD BE PLACED IN THEDISCONNECTED POSITION AND TAGGED. ALSO,THE REMOTE EQUIPMENT SHOULD BE ISO-LATED FROM ANY OTHER POWER SOURCESCONNECTED TO IT.

The primary circuits of metal-clad switchgear areinsulated in order to reduce the size of the equipment.However, this insulation in most instances, requires acertain amount of air gap between phases and toground to complete the insulation. Placing an object,tool, or body part in the insulation air gap can cause abreakdown in the primary circuit to ground and cause ashort circuit.

Care should be exercised during maintenance andchecking procedures to prevent accidental circuitbreaker tripping or starting operation.

CAUTION

When the metal-clad switchgear is energized,inserting a tool, human body part, or otherconductive object in the insulation air gap,causes a breakdown in the primary circuit toground and can result in a short circuit, whichcan result in personal injury and/or seriousdamage to equipment.

The switchgear structure and connections should begiven the following overall maintenance at leastannually.

A. Equipment Condition: Thoroughly clean theequipment, removing all dust and other accumula-tions. Wipe clean the buses and supports. In-spect the buses and connections carefully forevidence of overheating or weakening of theinsulation.

B. Mechanisms and Wear points: Clean mecha-nisms and lubricate wear points. The applicationof lubricants should be held to a minimum toreduce the accumulation of dust and dirt.

C. Abnormal Wear: Check primary disconnectingdevice contacts for signs of abnormal wear oroverheating. Use a good grade of silver polish toremove deposits from the silver surfaced contacts.Discoloration of the silver surfaces is not ordinarilyharmful unless atmospheric conditions causedeposits, such as sulfides, on the contacts.Apply a thin coat of contact lubricant to the maincontacts before replacing the circuit breaker.

D. Other Disconnecting Contacts: Inspect all primaryand secondary disconnecting contacts, such asthose on the rollout transformer, for abnormalwear, fatigue, or overheating. Replace the con-tacts, if necessary. Otherwise, clean the maindisconnecting contacts with a good grade of silverpolish.

E. Control Contacts: Contacts should be inspectedand dressed or replaced when the surface be-comes seriously pitted. Unless repetitive duty hasbeen experienced, little attention should berequired.

F. Secondary Wiring: Check all wiring connectionsfor tightness, including those at the current andpotential transformers and at the terminal blockswhere circuits leave the switchgear. Ensure thatthe secondary wiring connections are properlyconnected to the switchgear ground bus.

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G. Mechanical Parts: Visually check and manuallyoperate mechanical moving parts such as theshutter, TOC and MOC switch assemblies, theposition interlock, hinged doors, and the roll-outfeatures of the transformers and fuses. Examinemechanical mating parts such as the levering-inarms and the guide channels.

H. Ventilation: Check all labyrinths, grillwork, and airpassages for obstructions and accumulations ofdirt. The air space under outdoor switchgear,which is necessary for the entrance of ventilatingair, should be cleaned of leaves and other possibledebris. Replace or clean dirty filters.

I. Battery and Charging Equipment: Special atten-tion should be given to the control battery becauseit is an important item for switchgear operation. Toprovide long life and reliable service for the battery,perform frequent inspections and tests recom-mended in the battery supplier’s instructions. Atthe same time the battery is checked, inspect thebattery charger and remove accumulations of dustand dirt.

J. Anchor Bolts: Check to see that all anchor boltsand bolts in the structure are tight.

K. Heaters: If the switchgear is equipped withheaters, check to see that all heaters are ener-gized and operating.

L. Records: The condition of each switchgear unit atthe time of inspection should be listed in a perma-nent record to become a guide for anticipating theneed for replacements or for special attentionbetween the regular maintenance periods. Insula-tion resistance tests are suggested for checkingthe insulation. A series of these tests will indicateany tendency toward a reduction in dielectricstrength of the insulation. Insulation resistancereadings should be taken before and after cleaningthe equipment and, insofar as possible, undersimilar conditions at successive periods. Recordsshould include the insulation resistance reading,

the temperature, and the humidity, either bydefinite reading or description. Acceptable limitsvary with the extent and design of the bus struc-ture. In contrast to a small installation, the longerswitchgear assemblies have a more extensive busstructure with a greater number of insulators.Therefore, there are a larger number of parallelinsulation resistance paths to ground, which tendsto decrease insulation resistance readings. Thisvariation in insulation resistance between differentswitchgear assemblies emphasizes the value of aseries of readings which can be charted to estab-lish a normal insulation level so that progressiveweakening of the insulation can be recognized.

M. Abnormal Conditions: Local atmospheric condi-tions such as high humidity, salty atmosphere,corrosive gases, heavy dust, extreme heat, orsevere operating conditions, are considered to beabnormal, and more frequent equipment inspec-tions are required.

A series of quarterly inspections should be per-formed to analyze the effect of local abnormalconditions on equipment. Then an inspection andmaintenance schedule can be established tomaintain the equipment in a satisfactory condition.

If maintenance and inspection frequency inabnormal conditions interferes with operating andproduction schedules, consideration should begiven to placing the equipment in a relatively tightroom. Clean air can be pumped into the room tocreate positive air pressure and decrease expo-sure of the equipment to abnormal conditions. Inareas where the ambient temperature is relativelyhigh, cooling the air will improve equipmentprotection from extreme heat conditions. A lessfrequent maintenance schedule can be estab-lished when equipment is protected from abnormalconditions.

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VII. RECOMMENDED RENEWALPARTS AND REPAIRPROCEDURE

A. ORDERING INSTRUCTIONS

Order Renewal Parts from Powell Apparatus ServiceDivision (PASD) on the Powell Web site at http://www.powellservice.com, or call 1-800-480-7273.

1. Always specify complete nameplate information,including:

a. Type

b. Serial Number

c. Rated Voltage

d. Rated Amps

e. Impulse Withstand

f. Control Voltage (for control devices and coils)

3. Specify the quantity and description of the part,and the instruction bulletin number.

a. If the part is in any of the recommendedrenewal parts tables, specify the catalognumber.

b. If the part is not in any of the tables, a descrip-tion should be accompanied by a markedillustration from this instruction bulletin, aphoto, or a sketch showing the part needed.

4. Standard hardware, such as screws, bolts, nuts,washers, etc., should be purchased locally.Hardware used in bolted joints of conductors mustbe SAE Grade 5 or better to insure proper clamp-ing torque and to prevent the joints form overheat-ing. The hardware should be plated to detercorrosion.

B. RECOMMENDED RENEWAL PARTS

It is recommended that a sufficient amount of renewalparts be stored in stock to enable the prompt replace-ment of any worn, broken, or damaged parts. Asufficient amount of stock parts minimizes serviceinterruptions, which are caused by breakdowns, andsaves time and expense. When continuous operationis a primary consideration, a greater amount of re-newal parts should be stocked, the quantity should beconsider on the severity of the service and the timerequired to secure replacements.

Furnished spare or replacement parts may not beidentical to the original parts, since improvements aremade occasionally. However, the furnished parts areinterchangeable with the original parts. A recom-mended quantity of spare replacement parts isprovided. Therefore, based on how the equipment isto be used, the purchaser determines the quantity ofreplacement parts that may be needed.

Powell Electrical Manufacturing Company recom-mends that only qualified technicians perform mainte-nance on circuit breakers. To deter a break in service,a spare circuit breaker should be kept on site. Shoulda circuit breaker need replacing, the spare circuitbreaker should be installed and the malfunctioningcircuit breaker should be returned to the factory forreconditioning.

34


Table C. Accessories

Catalog Description Breaker Type Qty. Illustration No. per

Standard Closed-Door Brk.Racking Racking

1 Secondary 51555G01 51555G03 1DisconnectOverride Device

2 Manual 50235-P1 50235-P1 1ChargingHandle

3 Racking Handle 50218G01 50218G01 1

4 Racking 51066G01 NA 1StartExtension

5 CPT 90421G01P 90421G01P 1SecondaryDisconnect

6 PT 90422G01P 90422G01P 1SecondaryDisconnect

7 Umbilical Cord 51702G01 51702G08 1

NA 51702G11 1 (57")

8 Powel-Lube Powl-Lube-102® Powl-Lube-102® 1LubricationKit

35


Table D. Troubleshooting Topics

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36


Index

A

Abnormal Conditions 34

Angle Shipping Bracket 25

ANSI, IEEE, and NEMA Standards 6

Anti-Condensation Heaters 14

Applying PVC Boots 22

Auxiliary Enclosures and Compart-ments 14

B

Battery and Charging Equipment 34

Breaker connected 16

Breaker test position 13

Breaker test/disconnected 16

C

Circuit breaker

Interlocks 13

Racking mechanism 12

Circuit Breaker Compartment SafetyProvisions 11

Circuit breaker withdrawal 10

Cleaning Bus Insulation 22

Closed-door racking 16, 28

Connections 20

Main bus bars 20

Control conduits 24

Control Power Transformer 14, 15

Control Power Transformer Rollout24

Control power transformer rollout 24

D

DC high potential testing 32Disconnecting Contacts 33Door alignment 19Drawings and Diagrams 17Dummy removable elements 31

E

Electrical Operation 26

F

Factory Dielectric Test 10

Field Dielectric Test 10

Floor-anchoring preparation 18

Fuse Disconnecting Device 15

Fuse Rollout 25

G

Ground bus connections 20Ground fault current transformers

23Grounding 20

H

Heaters 14

I

Indoor Metal-clad Switchgear 18Installation 16Instruction bullentins on the web

6Instruction bulletin conflict with

other documents 6on the web 6

Introduction 6Other items of caution 6Purpose 6Instruction bulletins on the Web 6

Insulating primary cables termina-tions 23

Insulation resistance tests 34Interior of Metal-Clad Switchgear

11

K

Key interlocks 29, 31

L

Levering-in arms 34Lift truck 20Lighting 16Lubricants 33

M

Main bus assembly 21Main bus, main bus taps, and

ground bus 15Maintenance 33Mechanism-operated cell switch

(MOC Switch) 30Miscellaneous parts 36

O

One-high Construction 9Operation 25Outdoor equipment 19Outdoor metal-clad switchgear 19

P

Position Interlock 29Positioning the Metal-clad

switchgear 17Powell Apparatus Service Division

35Power connections 20Power Frequency Withstand 10PowlVac® Metal-clad Switchgear

9Preparation of floor-anchoring 18Primary cables 22Primary compartment 10Primary disconnect 15Primary enclosure 10Proper Bolt Assembly 20PVC boot installation 22

R

Racking Mechanism 28Receiving 16Removable element

dummy removable element 31ground and test device 31

Removable Element PositionInterlock 29

Rremovable elements 16Renewal parts 16Ring-type current transformers 15Rollout Carriage 14, 15, 24Roof entrance bushing 24

37


S

Safety 6Safety labels 8Safety of personnel 6Secondary compartment 10Shutters 26Special compartments 11Standard open-door racking 28

T

Taping of roof bushing 22Test and Inspection 31Testing 31The removable element 20Through-door racking 28Torque values 16Truck-Operated Cell Switch (TOC)

28Two-high Construction 9

V

Vacuum circuit breakers 6Voltage rating 10Voltage transformer (VT) control

power transformer 24Voltage transformer rollout carriage

14

W

Web site 16Wrapping of joints 22

X

X-rays 7

38

POWELL

INDUSTRIES, INC.

POWELL ELECTRICAL MANUFACTURING COMPANY8550 MOSLEY DRIVE • HOUSTON, TEXAS 77075 USA

PHONE (713) 944-6900 • FAX (713) 947-4453http://www.powellelectric.comhttp://www.powellservice.com

©2001 POWELL ELECTRICAL MANUFACTURING COMPANY ALL RIGHTS RESERVED REVISION 11/2003

IB-51000B

Documents

Transcript of IB-51000B