Control Systems Fan Motors

Control Systemsfor Cooling Tower

Fan Motors

TR-CS91

1Control Systems for Cooling Tower Fan MotorsContents

Page

Motor control required by electrical codes ............................................................................ 3Wiring diagrams symbols and general forms ..................................................................... 4Control enclosures NEMA types ........................................................................................ 5Sizing short-circuit protection ................................................................................................ 6Disconnect (safety) switch .................................................................................................... 7Circuit breaker ....................................................................................................................... 8Combination starter ............................................................................................................... 9Lightning arrester .................................................................................................................. 9Manual controller ................................................................................................................... 9Magnetic controller ................................................................................................................ 9Across-the-line starters ....................................................................................................... 10Reduced voltage starters .................................................................................................... 11Reconnectable starters ....................................................................................................... 14Special features .................................................................................................................. 15Control of magnetic starters ................................................................................................ 16Control for motor heating .................................................................................................... 17Motor overload protection ................................................................................................... 18Sizing of motor-overload protection .................................................................................... 18Soft start motor controller .................................................................................................... 21Variable frequency drive ..................................................................................................... 21Programmable controllers ................................................................................................... 22Purchasing information ....................................................................................................... 23Wiring diagram of single speed motor with time delay ........................................................ 24Wiring diagrams of two speed motors with various special features.............................. 25-32

Note: This file was revised in 91. This is not it, it is the original from PageMaker 2. Check over the illustrationscarefully to find which Fig was revised. DL 6-26-95.

2List of Tables

Table Page

1 Diagram symbols and letters .................................................................................... 42 Motor connections ..................................................................................................... 43 Motor design voltages ............................................................................................... 54 Locked rotor code letters .......................................................................................... 65 Max. rating or setting of motor branch-circuit protective devices .............................. 66 Recommended dual-element fuse sizes ................................................................... 77 Typical circuit breaker sizes ...................................................................................... 78 Typical disconnect switch ratings .............................................................................. 89 Standard fuse sizes .................................................................................................. 8

10 HP ratings for manual starters .................................................................................. 911 Characteristics and costs of magnetic starters ....................................................... 1012 HP ratings for magnetic starters ............................................................................. 1113 HP ratings for high voltage controllers .................................................................... 1114 Average motor amps & conductors for 200 V & 230 V ........................................... 2015 Average motor amps & conductors for 460 V & 575 V ........................................... 20

3Motor Control Required byElectrical Codes

This section describes the various protective devices, controls, andenclosures required for this equipment by most electrical Codes.Refer to the Codes for alternates which are allowable under certainconditions.

Required Devices1. Disconnecting Means to disconnect motor and controller

from the circuit. It must either open all ungrounded conductorsand be in sight from* controller or it must lock in the openposition. This design must indicate whether switch is open orclosed. The disconnect must be a switch rated in horsepoweror a circuit breaker of the inverse time or instantaneous triptype. The disconnect, either switch or breaker, for 600 volts orless motor circuits must be ampere rated for at least 115% offull load current. It must also be capable of interrupting stalled-rotor current.

2. Motor Feeder Short-Circuit Protection to protect themotor-branch-circuit conductors, the motor control apparatus,and the motors against overcurrent due to short circuits orgrounds. There must be one in each ungrounded conductor. Itmust carry motor starting current, but not over 400% of full loadcurrent. See Tables 4 and 5 for sizing.

3. Motor Controller to start and stop the motor. Select thecontroller for motor basic HP and voltage. See Tables 10, 11,14 and 15.

4. Overload Protection to protect the motor, control apparatusand the branch-circuit conductors against excessive heatingdue to motor overloads, stalled rotor and excessive cycling.Select overloads sized at 125% or less of motor full load currentfor motors with service factor of at least 1.15. Overload sizemust not exceed 115% of full load current for all other motors.Use three Running Overcurrent units.

Note: Items 1 through 4 are available in a pump panel orcombination starter.

5. Conductors supplying a single motor must have a carryingcapacity not less than 125% of motor full load current.Conductors supplying more than one motor must have acarrying capacity not less than 125% of full load current ratingof the highest rated motor plus the sum of the full load currentratings of the rest of the motors. Voltage drop for conductorsmust not exceed 3% on the branch circuit.Any conductor intended only for grounding purposes must becolored green unless it is bare. Grounded current carryingconductors must be white or natural gray color. All ungroundedconductors of the same color must connect to the same un-grounded feeder conductor. The conductors for systems ofdifferent voltages must be different colors.

6. Non-Fused Disconnect Switch Not required if Item 1 can lockin open position or is within sight from* motor.Motors and control boxes must be grounded.

*in sight from must be visible and not more than 50 feet distant.

Item Contained In

ElectricalSupply

Fusible Safety Switch

orCircuit Breaker

Manual orMagneticStarter

Non-FusedDisconnect SwitchIn Sight from Motor

Motor

Conductors

43 Phase Single SpeedDual Voltage Y (most common) Connection

Table 2 - Motor Connections

Wiring Diagrams

T6

T9

T3

T5

T8

T2

T4

T7

T1

T1T4T7T9T6T3

T8T5 T2

T6

T9

T3

T5

T8

T2

T4

T7

T1

L1 L2 L3 L1 L2 L3

T1

T6

T3T1 T2

T2

T4

T4T6

L1

T5T3

T5

L2 L3

L1 L2 L3

T4

T1

T2T3

T5 T6

High Voltage Low VoltageConnection Connection

Low Speed High SpeedConnection Connection

3 Phase 2 Speed ConsequentPole (1 Winding) Variable Torque

By far, the largest percentage of cooling tower motorsare three phase squirrel cage induction type. Onlythese motors appear in the diagrams. For reference,the three phase motor winding connections most often

used on cooling tower motors appear below. Toreverse a three phase motor, change any two of thethree leads (L1, L2, and L3).

*NO - normally open, NC - normally closed - contact position when not energized, pushed, etc.F - Forward LF - Low Forward CR - Control Relay OL - OverloadR - Reverse LR - Low Reverse M - Program Timer LOL - Low OverloadH - High HF - High Forward TR - Time Relay HOL - High OverloadL - Low T1,T2 - Motor Terminal L1,L2 - Line Terminals

A1 XA2 X

Low High

A1 XA2 X

Hand Off Auto

Temperature Push Buttons Pilot Light TransformerActuated Switch Selector Switch Single Circuit Double Circuit Letter Iron Core

NO* NC* 2 Position 3 Position NO NC NO NC IndicatesColor

Contacts Coil Overload Relay A.C. MotorInstant Operating Timed Contacts - Contact Action Thermal Single ThreeNO NC Retarded When Coil is Phase Phase

Energized De-EnergizedNO NC NO NC

A1

A2

A1

A2

Table 1 - Diagram Symbols and Letters

R

There are two common types of wiring diagrams. Thecontrol equipment supplier provides the standardWiring Diagram, showing the physical layout ofcomponents and wiring. These diagrams depict theexact connections required. Each manufacturer usesunique connection points and physical layout, so eachdrawing applies only to one manufacturer.

Elementary Diagrams show the operation of a circuit

in the simplest manner with no attempt to show physi-cal layout. This requires separation of the coils fromtheir contacts. A letter designation ties coil S andcontact S. Only Elementary Diagrams appear in thismanual. All cooling tower motors and control enclo-sures must be grounded, even though groundingconnections do not appear in this manual. The dia-gram symbols are shown below:

5Control EnclosuresThe National Electrical Manufacturers Association(NEMA) has established standard types of enclosuresfor control equipment. Types most commonly usedwith cooling towers are described below.

Type 1 General Purpose This enclosure isintended primarily to prevent accidentalcontact with the control apparatus. It issuitable for general purpose applicationindoors under normal atmospheric condi-tions. It serves as protection against dustand indirect, light splashing. It is not dust-proof.

Type 3 Dust-tight, Rain-tight and Sleet (Ice)Resistant This enclosure is intended foruse outdoors to protect the enclosed equip-ment against windblown dust and water. It isnot sleet (ice) proof. This enclosure musthave watertight conduit connections, mount-ing means external to the equipment cavity,and locking provision.

Type 3R Rain-tight This enclosure is intended foruse outdoors to protect the enclosed equip-ment against rain. It is not dust, snow orsleet (ice) proof. When completely andproperly installed, this enclosure preventsentrance of rain above the level of the lowestlive part. The 3R enclosure prevents theentrance of a rod .125" in diameter except atdrain holes. Drain holes will not permit entry

of a rod larger than .250" diameter. Liveparts must be at least 4" from the nearestdrain hole.

Type 4 Water-tight A water-tight enclosure mustexclude water. It must pass a hose test.This enclosure is adequate for outdoor useon a cooling tower. It is usually a gasketed304 stainless steel enclosure. Type 4X is awater-tight corrosion resistant enclosure thatwill pass a 200-hour salt fog test.

Type 7 Hazardous Locations Class I Air Break This enclosure meets the applicationrequirements of the National Electrical Codefor Class I, Group A, B, C, or D hazardouslocations. These locations may containspecific types of flammable gases or vapors.Refer to the Code for more complete defini-tions of hazardous locations*. Type 7enclosures are intended for indoor use butare sometimes used outdoors on coolingtowers.

Type 9 Hazardous Locations Class II Thisenclosure is designed for use in Class II(combustible dust), Group E, F, or G areas.

Type 12 Industrial Use This enclosure is used forindustrial applications to prevent entrance offoreign materials such as dust, lint, fibers, oilseepage, or coolant seepage.

*The Code defines hazardous locations in Division 1 and Division 2. In general, starters for either location division must be inexplosion-proof enclosures. Motors for Division 1 locations must also be explosion-proof. Motors for Division 2 locations canbe any enclosure, so long as motor does not employ sliding contacts, centrifugal switches or other types of switching mecha-nisms, or integral resistance devices.

Power System Point of UtilizationVoltages (Motor Design) Voltage

120 115208 200240 230480 460600 5752400 23004160 40004800 46006900 6600

Table 3 - Motor Design Voltages

6Disconnect Means and Short Circuit Protection

Sizing Short-Circuit Protection

letter and full load current of the motor to properly sizethe short circuit protection for a given motor. Thesevalues appear on the motor name plate.

Table 4 lists the locked rotor kilovolt amperes for codeletters appearing on motor name plates. Table 5 liststhe maximum rating or setting of motor branch circuitprotective devices.

Actual locked rotor current of a motor might approach600% of full load current. However, the proper sizefuse or circuit breaker will not go out on a normal motorstart.

A properly sized device serving as both disconnectmeans and short circuit protection must:

(1) Carry normal circuit current continuously(2) Safely switch the circuit under normal or

abnormal conditions(3) Prevent overcurrents of a predetermined

magnitude for a particular time interval, and(4) Automatically and safely interrupt current of

any magnitude that the system can produce.

Either a circuit breaker or fusible disconnect switch canserve as a disconnect means and short-circuit protec-tion. The designer must know the locked rotor code

Table 4 - Locked Rotor Code LettersCode Letter KVA per HP Code Letter KVA per HP

A 0-3.14 L 9.0-9.99B 3.15-3.54 M 10.0-11.19C 3.55-3.99 N 11.2-12.49D 4.0-4.49 P 12.5-13.99E 4.5-4.99 R 14.0-15.99F 5.0-5.59 S 16.0-17.99G 5.6-6.29 T 18.0-19.99H 6.3-7.09 U 20.0-22.39J 7.1-7.99 V 22.4-and upK 8.0-8.99

Table 5 - Rating or Setting ofMotor Branch-Circuit Protective Devices

Percent of Full Load CurrentNontime Dual Element Instantaneous Inverse

Type of Motor Delay (Time Delay) Trip TimeFuse Fuse Breaker BreakerMax. Max. Recom- Max. Max. Recom-

mended mendedAll AC single-phase and poly-phase squirrel cage andsynchronous motors with full-voltage, resistor or reactorstarting:

No Code Letter 300 175 125 700 250 150-225%Code Letter F to V 300 175 125 700 250 150-225%Code Letter B to E 250 175 125 700 200 150-200%Code Letter A 150 175 125 700 150 150%

Where max. rating in table 400% not 225% 1300% 400% (with fullabove is not sufficient for exceeding load current lessstarting current of motor the 600 amps than 100 amps)max. rating can be increased to 300% (with fullthese percent values load current

greater than 100amps)

7Table 7 - Typical Circuit Breaker Available SizesThermal Magnetic Instantaneous Trip

15 90 450 Amp Trip Amp Trip20 100 500 Rating Range Rating Range25 125 600 3 8-28 225 300-225030 150 700 7 18-70 400 500-400035 175 800 15 50-180 600 625-900040 200 900 30 100-350 800 625-900045 225 1000 50 150-58050 250 1200 100 300-110060 300 1400 150 750-150070 35080 400

Table 6 - Recommended Dual Element Fuse Sizefor Overload and/or Short Circuit Protection

of Three Phase Motors with a 1.15 or Larger Service FactorVoltage

200 Volts 230 Volts 460 VoltsFuse Size Fuse Size Fuse Size

Overload Short* Overload Short* Overload Short*Full & Short Circuit Full & Short Circuit Full & Short Circuit

Load Circuit Protection Load Circuit Protection Load Circuit ProtectionHP Amps Protection Only Amps Protection Only Amps Protection Only1/2 2.3 2.8 4 2.0 2.5 3.5 1.0 1.25 1.83/4 3.2 4 5.6 2.8 3.5 5 1.4 1.6 2.5

1 4.1 5 8 3.6 4.5 6.25 1.8 2.25 3.21 1/2 6.0 7 12 5.2 6.25 9 2.6 3.2 4.5

2 7.8 9 15 6.8 8 12 3.4 4 63 11.0 12 20 9.6 12 15 4.8 5.6 95 17.5 20 30 15.2 17.5 30 7.6 9 15

7 1/2 25.3 30 45 22 25 40 11 12 2010 32.2 40 60 22 35 50 14 17.5 2515 48.3 60 80 42 50 70 21 25 4020 62.1 70 100 54 60 90 27 30 5025 78.2 90 110 68 80 110 34 40 5030 92.0 110 150 80 100 125 40 50 7040 119.6 125 175 104 125 150 52 60 8050 149.5 175 200 130 150 200 65 80 11060 177.1 200 250 154 175 200 77 90 12575 220.8 250 300 192 200 300 96 110 150

100 285.2 350 400 248 300 350 124 150 175125 358.8 400 500 312 350 450 156 175 200150 414.0 500 360 405 500 180 200 250200 552.0 600 480 600 240 300 350250 300 350 500

* Based on wire size in Tables 14 and 15 for RH, RHW, RVH, THW, THWN, & XHHW wire.

Disconnect (Safety) SwitchDisconnect switches are rated by amperage andhorsepower. A disconnect switch for a motor load ishorsepower rated. It must carry 115% of motor fullload current continuously and must be capable ofinterrupting motor stalled-rotor current. Many fusibleswitches have three horsepower ratings: standard

fuse, dual element fuse, and non-fuse. See Table 8 onPage 8.

Manufacturers differ slightly in horsepower rating oftheir switches. Typical values follow:

8Circuit Breaker

They do not have to be replaced when operated. Theyalso prevent operating the motor single phase. Circuitbreakers can also be equipped for remote operation.Low voltage (600 volts and less) circuit breakers are ofthe air break type. Both oil and air type breakers areavailable for high voltage systems. Air circuit breakersare rated 15, 20, 30, 40, 50, 60, 70, 90, 100, 125, 150,175, 200, 225, 250, 300, 350, and 400 amps. They areavailable in NEMA 1, 3R, 4, 7, 9 and 12 enclosures.

Circuit breakers used for motor protection usually haveboth thermal and magnetic trip elements. The thermalelements protect on overloads where inverse timetripping is desired. The magnetic trip elements in-stantly operate the breaker in case of dangerousoverload or short-circuit faults. Usually circuit breakersdo not operate as fast as fuses at high overcurrents,but operate faster on normal overloads.

Circuit breakers offer certain advantages over fuses.

Table 9 - Standard Fuse Sizes (Amperes)250 or 600 Volts

Single Element Dual Element1 35 100 300 0.1 1.0 2.5 6.25 20 70 2003 40 110 350 0.15 1.125 2.8 7 25 80 2506 45 125 400 0.2 1.25 3.2 8 30 90 300

10 50 150 450 0.3 1.4 3.5 9 35 100 35015 60 175 500 0.4 1.6 4.0 10 40 110 40020 70 200 600 0.5 1.8 4.5 12 45 125 45025 80 225 0.6 2.0 5.0 15 50 150 50030 90 250 0.8 2.25 5.6 17.5 60 175 600

Standard ampere ratings are 30, 60, 100, 200, 400,600, 800, and 1200 amperes. Disconnect switches areavailable in NEMA Type 1, 3, 3R, 4, 7, 9 and 12enclosures.

Do not use plug type fuses at voltages greater than 125volts between conductors except in a grounded neutralsystem with less than 150 volts from conductors toground. Therefore, they are inappropriate for mostthree phase systems. Cartridge type fuses are avail-able with either renewable or non-renewable fuse

elements.

Good practice dictates using dual-element fuses ratherthan one-time fuses. Dual-element fuses interrupthigher fault currents, generate less heat in the controlbox, and permit use of smaller fuses for better protec-tion. In addition, if a fuse clip is loose on a one-timefuse, the case can carbonize and fail when the fuseblows. A loose clip on a dual-element fuse will causethe fuse to blow before the case can carbonize.

Table 8 - Typical Disconnect Switch Horsepower Rating240V - 3 Phase 480V - 3 Phase 600V - 3 Phase

SwitchAmpere Standard Dual Non Standard Dual Non Standard Dual NonRating Fuse Fuse Fuse Fuse Fuse Fuse Fuse Fuse Fuse

30 3 7.5 7.5 5 15 20 7.5 20 2060 7.5 15 15 15 30 50 15 50 60

100 15 30 30 25 60 75 30 75 100200 25 50 50 50 125 125 60 150 150400 50 125 125 100 250 250 125 350 350600 75 200 150 400 400 200 500 500

9Combination Starter

equipment. Install arresters on the incoming side asnear as practical to the piece of equipment to beprotected. Connect one arrester element to eachungrounded lead.

Usually, to protect a motor, it is necessary to use asecondary class arrester along with a surge-absorbingcapacitor. A secondary class arrester is designed forsecondary distribution systems such as those supply-ing motors. Arresters consist of a spark gap and adevice to limit or quench the spark. Each manufactureruses his own method or material to limit the spark.Lightning arresters are usually rated for the maximumphase-to-phase and phase-to-ground voltage.

A combination starter includes circuit breakers anddisconnect switches as part of the motor controller.

Lightning Arrester

Lightning damage to motors and control equipment isusually caused by high voltage induced in the powerline rather than lightning hitting the motor or controldirectly.

Lightning can cause immediate failures or it canweaken insulation, causing failures at a later date. Inareas where thunderstorms are frequent, it is advisableto install lightning arresters to protect motors and other

Table 10 - Horsepower Ratings for Across-the-Line Manual StartersHorsepower at:

NEMA 60 Hz Three Phase Single PhaseSize 200 or 50 Hz 60 Hz 50 or 60 Hz 50 or 60 Hz

230 V 380 V 480 or 575 V 115 V 230 VM-0 3 5 5 1 2M-1 7.5 15 10 2 3

M-1P 3 5

Manual controllers are available for reversing or two-speed two-winding motor control. Single phasecontrollers are available with selector switch and pilotlight.

Manual Controllers consist of snap-action switch(es)and overload(s). They are available in NEMA 1, 4, 7,9, and 12 enclosures. Standard sizes appear in Table10.

Manual Controller

Motor Controller

Magnetic Controller

Types of Magnetic Starters

use of reduced voltage or reconnectable type startersfor larger horsepower motors. Reduced startingcurrent and torque, and increased starting time typifyreduced voltage and reconnectable type starters.Therefore, the designer must allow sufficient torque toaccelerate the load and to keep starting time shortenough to avoid overheating the motor.

The motor controller normally used on cooling towers isa magnetic starter. The standard magnetic starter usesa magnetic coil to close contacts and springs and/orgravity to open them. Some type of pilot device, suchas a push button or float switch, actuates the magneticcoil. The main types of magnetic starters are across-the-line, reduced voltage, and reconnectable.

Power company limitations on inrush current dictate the

10

L1

L2L3

F F F

M

B1

B2

STOP START

F

FUNCTION at 60F

FOL

Table 11 - Characteristics and Costs ofCommon Magnetic Starters Used for Squirrel-Cage Induction Motors

Across- Primary Auto- Partthe-Line Resistance Transformers Winding Star Delta

Connection Y Y Y Y YPhase Voltage V KV* KV V .58VStarting Current (phase) IS KIS KIS .6 TO .8 iS .333 ISStarting Current (line) IS KIS K2IS .6 TO .8 iS .333 ISStarting Torque TS K2TS K2TS .4 TO .48 TX .333 TSApprox. Cost Comparison C 4.2 4.3 3.0 (2 steps) 5.2

(closed (closedtransition) transition)

*K is a constant equal to the reduced voltage over the full line voltage.

Across-the-Line Starters: Across-the-line starters arethe most widely used. The transformer must haveenough capacity to allow the motors to be started thisway. The motor leads receive full voltage as soon asthe pilot device energizes the magnetic coil in anacross-the-line starter.

Table 12 lists sizes of across-the-line magnetic starters(including reversing) for use with single or multi-speedvariable-torque squirrel cage induction motors (non-plugging or non-jogging duty).

Standard Single Speed Across the Line Starterwith Hand-Off Auto Selector Switch, Push Button(Three-Wire) and Thermostat (Two-Wire) Control

B2 XB1 X

Hand Off Auto

Typical Current and Torque Curvesfor Design B Induction Motor

11

at a predetermined time interval.

This type of starter limits the inrush current, givessmooth motor and load acceleration, and provides ahigher starting cycle. Disadvantages of this starter arethe physical size of the starter and resistors and thepower loss in the resistors. Primary resistance typestarters are called close transition starting units.

Reduced Voltage Starters

Primary Resistance Starters: Reduced voltagestarters are either primary resistance type or auto-transformer type. The pilot device energizes themagnetic coil of a primary resistance starter, connect-ing the motor to the line through resistors. The resis-tors normally limit the motor voltage to 65% or 80% ofnormal voltage. A timer, energized at the same time asthe motor, times out and picks up the run contactorwhich in turn connects the motor directly across the line

Table 13 - Horsepower Ratings for High Voltage Controllersand Line Contactors

Size of Controller Continuous Horsepower Rating Induction Motors& Current Ratings Three Phase

Contactor Amperes 2200-2400 Volts 4000-4800 VoltsH 2 180 700 1250H 3 360 1500 2500

Table 12 - Horsepower Ratings for Across-the-Line Magnetic StartersSingle Speed and Multi-Speed Variable & Constant Torque

Horsepower at:Size Continuous Three Phase Single Phaseof Current Rating 200 V 230 V 380 V 460 or 575 V 50 or 60 Hz 50 or 60 Hz

Starter Amperes 60 Hz 60 Hz 50 Hz 60 Hz 115 V 230 V00 9 1.5 1.5 1.5 2 1/3 10 18 3 3 5 5 1 21 27 7.5 7.5 10 10 2 31P 36 3 52 45 10 15 25 25 3 7.53 90 25 30 50 504 135 40 50 75 1005 570 75 100 150 2006 540 150 200 300 4007 810 300 6008 1215 450 9009 2250 800 1600

12

FFF

STOP START OL

F

S

1 2 3

Motor

SSS

L1L2

L3R

ES

RES

RES

TR

2 Wire Control

OL

Auto-transformer Starters: Auto-transformers reducethe starting voltage in this type of starter. The advan-tages of this type of starter are:

The starter contains several voltage taps. The de-signer may select the correct reduced voltage for eachapplication. For motors up through 50 HP, 65% and80% voltage taps are included. For larger horsepowermotors, 50%, 65% and 80% voltage taps are included.

The transformer ratio reduces the line current for agiven torque.

Both open-circuit transition and closed-circuit transitionauto-transformer starters are available.

Open-circuit transition: A timer and the motor areenergized simultaneously through the transformer tap.

At a predetermined time, the timer opens the lines tothe primary of the auto-transformer, then connects themotor directly across the line. Disadvantages of thistype starter are: high cost, low power factor, completeloss of power when the motor is disconnected from theauto-transformer, and high inrush current when themotor is connected across the line.

Closed-circuit transition: Three transformers are firstconnected in wye and the motor is energized throughthe transformer taps. After a timed interval, the wyeconnections open, leaving the transformer secondarywinding in series with the motor. The motor is thenconnected directly across the line and the transformersare disconnected. Full voltage induces a lower currentpeak and complete loss of power does not occur.

Reconnectable Starters

TRF

S

Typical Wiring Diagram ofPrimary Resistance Starter

Typical Current and Torque Curveswith 65% Voltage on First Stepfor Design B Induction Motor

13

Motor

F

S

TR

TR

TR

SSS FFF

SS

OLOLOL

T1 T3

Stop StartL1

L3

L2

OL

4

3

T2

FSTR1 T

Motor

OLOLOL

T1T2

T3

Stop StartL1

L3

L2

OL

F

TR1TR1

FS FS

T T

2 Wire Control

2 Wire Control - Use Dotted Lines andRemove Jumper 3 to 4

TR

S

F

Typical Wiring Diagramof Auto-Transformer Starterwith Open-Circuit Transition

Typical Current and Voltage Curveswith 65% Voltage on First Stepfor Design B Induction Motor

TR1

S

T

F

Typical Wiring Diagramof Auto-Transformer Starter

with Closed-Circuit Transition

Typical Current and Voltage Curveswith 65% Voltage on First Stepfor Design B Induction Motor

14

T9T7T3T2T1 T8

OLOLOL OLOLOL

Motor

StopStart

S S S F F F

L1

L3

L2

OL

Fuse

S TR

Part-winding Starters: Reconnectable starters can behalf. The locked rotor current on the first step isapproximately 60% to 65% of full locked rotor amps.The locked rotor torque is approximately 46% to 49%of full locked rotor torque. Part-winding starting isprimarily used to allow the voltage regulator to adjust,preventing excessive line voltage reduction. With thismethod, a dip appears in the torque curve at halfspeed. Overloads and fuses for use with part-windingstarters should be sized for half the motor full loadcurrent and placed in each of the six lines to the motor.

Star-delta Starters: The motor must be wired for

running delta, with enough leads brought out to con-nect the motor for a star (or wye) start. In the first stepof starting with open transition, the motor is connectedwye and the timer energized. At a predetermined timeinterval, the motor is disconnected and reconnected tothe line wired delta. Locked rotor amperage on the star

connection is only 33% of the locked rotor amperageon delta connections. However, the voltage fluctuationcaused by disconnecting and reconnecting the motormay be objectionable.

Star-delta starters are available with closed transition.

either part-winding, or star delta type. Part-windingstarters require that the motor stator winding must bemade up of two or more circuits connected in parallelfor normal operation. Standard 230/460 volt motors,15 horsepower and larger, are generally suitable forpart-winding starting at the lower voltage. Check firstwith the motor manufacturer.

In the first step of part-winding starting, half the motorwinding and a timer are energized. At a predeterminedtime interval (usually one second), the second half ofthe motor winding is connected in parallel with the first

TR

S

F

2 Wire Control

Typical Wiring Diagramof Part-Winding Starting

Typical Current and Torque Curveswith Part-Winding Starting

for Design B Induction Motor

15

T3T2T1 T4

OLOLOL

Motor

Stop Start

F F F T T T

L1

L3

L2

OL

T6 T5

SS

TR

F S

S1 2 3

In the closed transition type, the motor remains con-nected to the line through resistors during the connec-tion change from star to delta.

Special Features

Single-Speed Motor Starters

Auxiliary Contacts: Auxiliary contacts, sometimescalled interlocks, are mechanically connected to thestarter so that energizing the starter coil opens thecontacts (N.C.) or closes the contacts (N.O.). Moststarters come with one auxiliary contact. This contactappears in the holding circuit with three-wire control orit can control operation of other equipment with two-wire control. Additional contacts (1 to 4, depending onstarter) are available factory installed or for fieldinstallation.

Push Buttons or Selector Switch on Cover: Pushbuttons, pilot lights, or selector switches are availablepre-installed on the cover of NEMA Type 1, 4, 7, 9, and12 starter enclosures. They are wired into the circuits

at the factory. Pilot lights are normally wired in parallelwith the coils whose operation they indicate (see wiringdiagram on page 24).

Control Transformer: Personnel safety sometimesdictates low voltage control circuits. To accomplishthis, the control circuit can be wired for connection to aseparate power source, or a control circuit transformercan be a part of the starter to provide a 115-volt controlcircuit voltage. Some control circuit transformers haveenough capacity for a 100-watt work lamp. A fuse inthe secondary circuit provides short circuit protectionfor the transformer and control circuit. The wiringdiagram on page 30 shows how to wire a controltransformer into the controls system.

Time Delay Contacts or Relays: Reversing a fanwithout a time delay imposes a heavy shock load onthe drive. Marley recommends a two-minute time delaywhen reversing so that the fan can slow down towindmilling speed before it actually reverses (seewiring diagram on page 24).

The timing head used by some manufacturers employs

S

F

T

TR

2 Wire Control

Typical Wiring Diagram ofStar-Delta Starter withOpen-Circuit Transition

Typical Current and Torque Curvesfor Design B Induction Motor

16

the starter coil and does not require a coil of its own(see page 24). Other manufacturers use a timer withits own coil. On page 24, these timer coils must be inparallel with the proper starter coil (forward timer coil inparallel with forward starter coil, etc.). Timers areavailable with two different types of contact operation:

Instantaneous operation on energization with timedelay operation on de-energization.

Time delay operation on energization with instantane-ous operation on de-energization.

Additional contacts without time delay are available.

On multi-fan towers, it is sometimes desirable toprevent more than one fan starting at the same time.Interlocks in the motor starters and time delay relayscan accomplish this goal. However, some means isnecessary to permit removing a fan from service formaintenance while the rest of the fans are operating. Asequence alternator can accomplish the same thing ifonly one fan is required at a time and alternating fans isdesirable.

Multi-Speed Starters

Multi-speed motor magnetic starters are available withthe same features listed for single-speed motor start-ers. The following additional features are also avail-able:

Compelling Relay: A compelling relay connected in amulti-speed starter allows the motor to start only at lowspeed. Any higher speed is available only after a low-speed start. Pressing any push button except lowspeed will not start the motor. This arrangementinsures that the motor will always first move the load atlow speed. The motor can only change from a higherto a lower speed after the stop button is pressed.

Accelerating Relays: A multi-speed starter equippedwith accelerating relays starts the motor at low speedand automatically accelerates it through successivesteps until the motor reaches the selected speed. Theoperator selects the motor speed by pressing theproper start button. Definite time intervals must elapsebetween each speed change. Individual timing relayscontrol each interval, and all are adjustable. The motorcan only change from a higher to a lower speed afterthe stop button is pressed.

Decelerating Relays: These are similar to accelerat-ing relays except that they prevent immediate reductionfrom a higher to a lower speed. Both the drivenmachinery and the motors suffer tremendous strains

when the motor changes to a lower speed withoutallowing the motor to adjust to the lower speed. Marleyrecommends a 20-second time delay before energizinga lower speed winding.

Control of Magnetic Starters

Three-Wire (Push Button) Control

The controls for magnetic starters are either three-wireor two-wire controls. Three-wire control is manualcontrol. An operator must push a button to start themotor.

Starters with three-wire control provide under voltageprotection for a motor. When the motor stops becauseof a voltage failure, it will not restart until the startbutton is pushed.

Separate push buttons select each speed and stop.Push buttons serve as momentary contact devices.Once the push button energizes the starter coil, thecircuit bypasses the start button. The circuit mayinclude any number of push buttons. Start buttons arein parallel and stop buttons are in series. Standard-duty push buttons are available with either normallyopen or normally closed contacts. Heavy-duty pushbuttons have both normally open and normally closedcontacts. Push buttons are also available with lock-outdevices, built-in lights, and different actuators andactuator guards. Indicator lights are available with orwithout attached transformer. Push buttons areavailable in NEMA Type 1, 4, 7, 9, and 12 enclosures.

Selector switches can serve the same function as pushbuttons. Since a selector switch is a maintainedcontact device, only one can be used to energize astarter wired for three-wire control. Any number can beused to de-energize a starter. Hand key or coil oper-ated selector switches are available with two or threecontact positions.

Two-Wire Control

The starter must use three-wire control to provide bothmanual and automatic starter control. Where onlyautomatic control is required, the magnetic starter iswired for two-wire control. Starters with two-wirecontrol provide under voltage release, which discon-nects the motor from the line if the voltage gets too low.However, the motor automatically goes back on the linewhen the voltage comes back up. Limit switches,pressure switches, temperature switches, and relaysused with two-wire magnetic starter control offerautomatic motor control.

17

Control for Motor Heatingusing the motor winding. The motor manufacturernormally installs the space heaters and determines thetransformer size necessary for single-phase heating.Neither space heaters nor single-phase heating shouldbe energized while the motor is running. Typical wiringdiagrams appear below.

The use of single-phase heating is normally limited tolow voltage (600 volts or less) squirrel cage inductionmotors. The wiring diagram shows a time delay relayto prevent connecting the transformer to the motor

winding until the motor voltages have collapsed. Anavailable solid state motor winding heater can beconnected to a single-speed full voltage motor starterwithout additional control.

Fan motors that will be idle for long periods shouldhave some method of heating. Elevating the motortemperature five or more degrees above ambientprevents condensation in or on the motor. Two com-monly used heating methods are electric space heatersand low (5% of normal) voltage single-phase heating

L1

L2L3

F F F

M

STOP START

F

OL

F

F

OLOLOL

MotorSpace Heater

F

Typical Wiring Diagram Showing Connections for Single Phase Heating

OLOLOL

F

STARTSTOP

F F F

OL

Motor

L1L2

L3

CR2

CR2

CR2TR

Heating Transformer

CR1 CR2

CR1F

CR1

F

R

GTR

CR2

Typical Wiring Diagram Showing Connections to Space Heater

R

G

18

Motor Overload Protection

motors can always accelerate the load across-the-linein 13 seconds or less. Refer any questions about fanstarting time to The Marley Cooling Tower Company.

In a cooling tower, the fan horsepower increases withhigh air density in the winter and decreases with low airdensity in the summer. Cooling tower fans are pitchedto draw contract horsepower for summer duty. Fanhorsepower quite often exceeds the motor name platehorsepower in winter when the air density is high; butthis does not hurt the motor. Allowable motor horse-power is limited by motor temperature, which consistsof ambient plus the temperature rise due to the powerlosses in the motor. The temperature rise in winter(due to increased power losses) is more than offset bythe drop in ambient temperature.

Starter overload capacities vary with ambient (seePage 19). Overloads can best protect a motor insummer and winter, without false tripping of the over-loads, if they are always at about the same ambient asthe motor. This can be done by installing the startersoutside near the motor. Overloads which are compen-sated to carry the same horsepowers at high or lowambient conditions should not be used with coolingtower fans.

Overloads as Part of the Safety Switch

Dual element fuses in a fusible safety switch give bothshort-circuit protection and motor-running overcurrentprotection. Where motors are protected by switchesdescribed above, dual element fuses should be used toprotect the starter and conductors.

Sizing of Motor-Overload Protection

Motor manufacturers select and install Type A overcur-rent devices. The proper size for a Type B devicedepends on the motor operating horsepower full loadcurrent, the starter enclosure, and the temperature ofthe starter relative to the temperature of the motor.Most overload selection tables apply to motors with aservice factor greater than 1.0. The overload heatersfor 1.0 service factor motors are normally smaller andtheir selection appears in a footnote with the table.Overload selection tables are usually attached to theinside of the motor starter enclosure. The proper sizefor a Type C device depends on the motor operatinghorsepower full load current.

The motor full load current appears on the motor nameplate. Currents vary with manufacturer and with motordesign (one-speed, two-speed, one-winding, etc.).Nominal current values for 60 Hz, 1800 RPM motorsappear in Tables 14 and 15.

The following types of motor overload protection areused:

Sensors Built into the Motor

Thermocouples (usually copper-constantan), imbeddedin the coils during assembly, provide a signal to read orrecord temperature or sound an alarm.

Resistance temperature detectors imbedded in thecoils provide a signal in a circuit to sound an alarm orturn off a motor on high temperature. They are nor-mally used only in form wound motors (large HP).

Thermistors, usually with a positive temperaturecoefficient, can provide a signal to an auxiliary circuit toswitch a motor starter off. The thermistors, imbeddedin the winding, have a constant resistance until thecritical temperature occurs. The resistance value thenchanges by a factor up to one hundred.

Special rate-of-rise temperature switches protect amotor against overloads and stalled rotor conditions.Two or more sensors installed in the end turns sense atleast two phases of a three-phase motor and turn offthe motor starter. They automatically reset when thetemperature drops about 15C. This type of protectorcan sense the rapid temperature changes caused by astalled rotor.

Thermostats used in motors are usually bimetallic-disctype attached to the winding end turns. They areavailable with either normally open or normally closedcontacts and reset automatically with about a 10Ctemperature drop. They do not normally protect amotor against the rapid temperature increases causedby a stalled rotor.

Sensors Built into the Motor Starter

Temperature and current sensitive relays in the motorstarter open the line to the holding coil of the magneticstarter. A three-phase motor requires three relays, onein each line. A single-phase motor normally requiresone relay. Properly sized relays trip at not more than125% of the full load current for motors with a 1.15 orlarger service factor (115% for all other motors).

NEMA classifies these overload relays by time currentcharacteristics. The class number indicates the time atwhich the relay will trip at 600% of the current rating.Class 10 relays trip in 10 seconds and are normallyused with hermetically sealed motors and other motorswhich can endure locked rotor current for only a veryshort time. Class 20 relays trip in 20 seconds and arenormally used on cooling tower motors and othernormal motor acceleration applications. Marley fan

19

Variation in Starter Overload Tripping Current with Ambient Temperatures

20

Wire & Conduit Sizes for Wire & Conduit Sizes forFull Load Amps Types RUW, T, TW Wire Types RH, RHW, RUH, THW, THWN, XHHW Wire

HP 460 V 575 V 460 V 575 V 460 V 575 VWire Conduit Wire Conduit Wire Conduit Conduit Wire Conduit Conduit

AWG or AWG or AWG or RH, RHW, THWN AWG or RH, RHW, THWNMGM MGM MGM RUH, THW XHHW MGM RUH, THW XHHW

1/2 1.0 0.8 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/23/4 1.4 1.1 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/2

1 1.8 1.4 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/21 1/2 2.6 2.1 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/2

2 3.4 2.7 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/23 4.8 3.9 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/25 7.6 6.1 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/2

7 1/2 11 9 12 1/2 14 1/2 12 1/2 1/2 14 1/2 1/210 14 11 10 1/2 12 1/2 10 3/4 * 1/2 12 1/2 1/215 21 17 8 1/2 10 1/2 10 3/4 * 1/2 10 3/4 1/220 27 22 6 1 8 1/2 8 1 * 1/2 8 1 1/225 34 27 6 1 6 1 6 1 1/4 * 3/4 8 1 1/230 40 32 4 1 6 1 6 1 1/4 * 3/4 6 1 1/4 3/440 52 41 3 1 1/4 4 1 4 1 1/4 * 1 6 1 1/4 3/450 65 52 1 1 1/4 3 1 1/4 3 1 1/4 1 4 1 1/4 160 77 62 0 1 1/2 2 1 1/4 2 1 1/4 1 1/4 3 1 1/4 175 96 77 000 2 0 1 1/2 0 2 * 1 1/4 2 1 1/4 1 1/4

100 124 99 0000 2 000 2 000 2 1 1/2 0 2 1 1/4125 156 125 300 2 1/2 0000 2 0000 2 1/2 * 2 000 2 1 1/2150 180 144 400 3 300 2 1/2 300 2 1/2 2 1/2 0000 2 1/2 2200 240 192 700 3 1/2 500 3 500 3 3 300 2 1/2 2 1/2

Wire & Conduit Sizes for Wire & Conduit Sizes forFull Load Amps Types RUW, T, TW Wire Types RH, RHW, RUH, THW, THWN, XHHW Wire

HP 200 V 230 V 200 V 230 V 200 V 230 VWire Conduit Wire Conduit Wire Conduit Conduit Wire Conduit Conduit

AWG or AWG or AWG or RH, RHW, THWN AWG or RH, RHW, THWNMGM MGM MGM RUH, THW XHHW MGM RUH, THW XHHW

1/2 2.3 2.0 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/23/4 3.2 2.8 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/2

1 4.1 3.6 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/21 1/2 6.0 5.2 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/2

2 7.8 6.8 14 1/2 14 1/2 14 1/2 1/2 14 1/2 1/23 11.0 9.6 12 1/2 14 1/2 12 1/2 1/2 14 1/2 1/25 17.5 15.2 10 1/2 10 1/2 10 3/4 * 1/2 10 3/4 * 1/2

7 1/2 25.3 22 8 1/2 8 1/2 8 1 * 1/2 8 1 * 1/210 32.2 28 6 1 6 1 6 1 1/4 * 3/4 8 1 * 1/215 48.3 42 3 1 1/4 4 1 4 1 1/4 * 1 6 1 1/4 * 3/420 62.1 54 2 1 1/4 2 1 1/4 3 1 1/4 1 4 1 1/4 * 125 78.2 68 0 1 1/2 1 1 1/4 2 1 1/4 1 1/4 3 1 1/4 130 92.0 80 00 1 1/2 0 1 1/2 0 2 1 1/4 2 1 1/4 1 1/440 119.6 104 0000 2 000 2 00 2 1 1/2 0 2 * 1 1/450 149.5 130 300 2 1/2 250 2 1/2 0000 2 1/2 * 2 000 2 1 1/260 177.1 154 400 3 300 2 1/2 250 2 1/2 2 0000 2 1/2 * 275 220.8 192 600 3 500 3 400 3 2 1/2 300 2 1/2 2 1/2

100 285.2 248 900 4 700 3 1/2 600 3 1/2 * 3 500 3 3125 358.8 312 2000 1250 4 1/2 900 4 3 1/2 700 3 1/2 * 3 1/2150 414 360 2000 1250 5 * 4 900 4 3 1/2200 552 480

Table 15 - Average Motor Full Load Amps and Minimum Conductor and Conduit Size (1984 N.E.C.) for 60 Cycle Induction Type A.C. Motor Circuits 460 V & 575 V

Table 14 - Average Motor Full Load Amps and Minimum Conductor and Conduit Size (1984 N.E.C.) for 60 Cycle Induction Type A.C. Motor Circuits 200 V & 230 V

21

Soft Start Motor ControllerSeveral manufacturers offer Soft Start Motor Control-lers. These controllers use silicon controlled rectifiers(SCRs) to ramp the motor starting voltage (starting atzero and increasing to full voltage over a period oftime). The starting time is adjustable from one secondup to 24 seconds or more, depending on the manufac-turer. The advantage of soft start is the reducedstarting torque and shock on the fan drive.

An energy saving feature in these controllers reducesthe voltage to the motor at partial loads. This reducesthe losses in the motor by reducing the magnetic fluxdensity. It also improves the power factor. The cost ofthese controllers is approximately $30 per horsepowerin a NEMA 12 enclosure.

A soft start controller is usually installed between theacross-the-line starter and the motor.

Variable Frequency DriveThe past few years have seen considerable develop-ment of variable frequency controls that permit operat-ing standard, three-phase, squirrel cage inductionmotors as variable speed motors. These controllersconvert one or three-phase a.c. power to d.c., then re-convert it to three-phase variable voltage and fre-quency power. They try to maintain constant volts percycle so that the motor torque remains constant at allspeeds. Motor cooling becomes less effective at lowspeeds, so some applications may require reducedload torque at lower speeds. However, this limitationdoes not apply to fan and pump applications.

Diode or SCR bridges convert the a.c. power to d.c.The drive also controls the voltage by adjusting thefiring point of the SCRs. Some users have reportedthat SCRs introduce noise back in the line, causingproblems with computers. An isolation transformerand/or suppression equipment either at the computeror at the variable frequency drive may be necessary ifthis occurs.

Diode bridges, on the other hand, cannot regeneratepower back to the a.c. line (regenerative braking).Manufacturers who use diode bridges instead of SCRsto convert to d.c. usually guarantee that they will notput noise back to the line. Since the d.c. from a diodebridge is at constant voltage, it is necessary to add anSCR or transistor to the output to control the voltage tosome inverters.

The device that changes d.c. back to variable fre-quency a.c. is called an inverter. Three basic inverterdesigns are common:

(1) Six steps voltage inverter (VSI).(2) Six steps current inverter (CSI).(3) Pulse width modulating inverter (PWM). This

inverter uses constant voltage d.c.

Most variable frequency drives in the 1 to 200 HPrange use voltage source inverters (VSI). Many 1 to 20HP units are the (PWM) type. The losses at full load inthe power source are about 3% for the VSI type and5% for the PWM type. Motor losses with a PWM

inverter are less than with a VSI inverter since thepower supplied is closer to a sine wave.

In addition, the motor losses on a VSI control increase10% to 20% because the input is a square wave ratherthan a sine wave source. The temperature rise in amotor varies almost directly with the losses. As anexample of these two effects, an 80C rise 90%efficient motor would have a 96C rise and be 88%efficient when operating on a square wave. Because ofthis effect, some motor manufacturers recommendusing a high efficiency 1.15 service factor motor with aninverter power source.

Motor starting time and torque and decelerating timeand torque are adjustable with a variable frequencycontroller. The cost per horsepower of variable fre-quency controls decreases as the horsepower capacityof the control increases. Cost and performance ofvariable frequency drives will continue to improve asdevelopment continues and the devices gain popular-ity. Base unit prices do not include a temperaturecontroller, start-up engineer, critical speed lockout,safety disconnect or motor starters to permit alternateoperation direct across-the-line.

The designer must consider several other restrictionswhen specifying a variable frequency controller for awater cooling tower. Splash lubricated gear reductionunits require a minimum operating speed for adequatelubrication. This minimum input speed varies with thegear unit design, and is between 440 and 750 RPM ona Marley Geareducer. The inverter controls mustprevent motor operation below the minimum speed.

Also, some tower components may have a naturalfrequency within the range of operating speeds of avariable frequency motor drive. If the equipmentoperates for any significant time at the critical speed, acatastrophic failure could occur. Therefore, the invertercontrols must prevent operation at or near a criticalfrequency. Most variable frequency control manufac-turers offer field-installed kits to lock out a 4 Hz bandaround a critical frequency.

22

Programmable ControllersIt has always been possible to reduce the cooling effecton a multi-fan tower by turning off fans or reducing fanspeed with a multi-speed motor. Either an operatorchanged speeds manually or automatic controls withthermostats changed the speed using relays andtimers.

A thermostat normally controlled each speed changeon each motor. The thermostats were all set at differ-ent temperatures to prevent changing speed on morethan one fan at a time. By adding timers or a multi-circuit timer, it was possible to use one thermostat(temperature) to increase speed and another thermo-stat (temperature) to decrease speed of all fans asrequired.

Programmable controllers are now available to in-crease or decrease fan speed; wait for the water

temperature to stabilize; then change another fanspeed. These controls can also prevent motor over-heating from excessive cycling. They still require twothermostats, one to increase fan speed and one todecrease fan speed. A dead band between the twotemperatures allows operation with no speed changerequired. Programmable controllers replace only thecontrol of the magnetic motor starters, not the magneticstarters themselves.

The cost of a programmable controller depends on thenumber of inputs and outputs required. An input couldbe a thermostat or selector switch, for example.Switching a motor speed would be considered anoutput. For example, 4 two-speed motors wouldrequire eight outputs to get eight changes in tower airrate.

23

Purchasing Information (for Control Equipment)The customer should specify the following informationwhen purchasing individual items of control equipment.

Magnetic Across-the-Line Starter

1. Single or multi-speed.2. Motor horsepower (each speed).3. Line voltage.4. Frequency (cycles).5. Number of phases. (Number of wires if two-

phase.)6. Full load motor current (at each speed if more

than one speed).7. Enclosure type by NEMA type number and size

number.8. Desired control type on cover: start-stop

buttons, plain cover, or selector switch markedHand, Off, and Automatic.

9. On multi-speed motor starters, state if conse-quent pole or separate winding. State if motoris constant torque, variable torque, or con-stant horsepower.

10. On Multi-speed and single-phase motor starters,send terminal diagram of motor.

11. State whether pilot control device is two orthree-wire. Three-wire is for push buttoncontrol. If two-wire, describe pilot device. Statevoltage if different from line voltage.

12. State if compelling relay, accelerating relay,decelerating relay, or extra interlocks aredesired on starter.

13. State if motor will be reversed. If two-speedmotor, will motor be reversed one-speed or two-speed. If reverse one-speed, which speed.

Timing Relay

1. Whether a.c. or d.c.2. Line voltage.3. If a.c., state frequency (cycles).4. Contact arrangement desired, (i.e., normally-

open or normally-closed).5. Enclosure type by NEMA number.

6. Timing range desired.7. Relay type: Fluid dashpot, Pneumatic,

Motor drive, or Electronic.

Push-Button Stations

1. Number of stations needed.2. Marking of each button.3. Enclosure type by NEMA number.4. State whether contacts are normally-open,

normally-closed, or both. Standard-duty buttonshave normally-closed or normally-openswitches. Heavy-duty buttons are all normally-open, normally-closed.

Safety Switch

1. Motor horsepower and full load current.2. Line voltage.3. Number of phases.4. Enclosure type by NEMA number.5. State if fuse holders are desired.6. State if fuses are to be included (extra).7. State if cover is interlocked.8. State the position and size of hub or conduit

openings, if not standard.

Float Switch

1. Voltage.2. Horsepower rating.3. Whether a.c. or d.c.4. If a.c., state phases.5. Chain or rod operated.6. Length of chain or rod.7. Enclosure type by NEMA number.

Temperature Switch (Thermostat)

1. Whether a.c. or d.c.2. Horsepower rating.3. Desired cut-in & cut-out temperatures.4. Voltage.5. If a.c. state phases.

24

STOP OLR RFWD

F F

CR1

CR2

R R R F F F REV

L1

L2

L3

FanMotor

T1 T2 T3

OL

Item Allen Bradley Cutler Hammer General Electric Square D WestinghouseStarter Bulletin 505 File A50 CR 309 Form Class 8736 Class A-211

Push Button Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2

Wiring Diagram of Three Phase Magnetic StarterSingle Speed Motor with

Reversing with Time Delay andPush Button Control

R

R

CR1

CR2

G

F

Minimum Time DelayReversing - 2 Minutes

25

HHH

HH

T2

A2

T5T6 T4T3T1

HOLLOL

FanMotor

A1 Stop

L L

L

L1

L3

L2

OLH HLow

HL

CR1

High L

L

T13T11 T12T3T1

HOLLOL

FanMotor

L H H H

L1

L3

L2

T2

L


Push Button Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2

L

H

CR1

Minimum Time DelayHigh to Low Speed - 20 Seconds

Wiring Diagram of Three Phase Non-Reversing StarterTwo Speed Consequent Pole Variable Torque Motor with

Time Delay on Deceleration and Push Button Control

A1 XA2 X

Run Safe

Note: If motor is separate winding type, usesame control circuit but change powercircuit to that shown at right.

26


Push Button Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2Selector Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2Switch

FanMotor

T1 T2 T3 T13T12T11

L1

L3

L2

LF LF LF LR LR LR HF HF HF

FanMotor

T1 T2T3

T5T4T6

L1

L3

L2

LF LF LF LR LR LR HF HF HF

HFHF

OL

HF

LF

HF

LR

LFCR3 CR2 CR1

CR3 CR2 CR1

CR3 CR2 CR1

2 Min LR

2 Min TR1

20 SecHF

A2

A1 StopVIBSW

LF

LR

HF

TR1

CR1

CR2

CR3

Minimum Time Delay1. High to Low Speed - 20 Seconds2. Reversing - 2 Minutes

Wiring Diagram of Three Phase Magnetic StarterTwo Speed Consequent Pole Variable Torque Motor with

Time Delay on Deceleration, Reversing Low Speed with Time Delayand Push Button Control

A1 XA2 X

Run Safe

Note: If motor is separate winding type, usesame control circuit but change powercircuit to that shown at left.

27

HH

RRR

L HHHLL

LOL HOL

FF F

H

CR1

T5T6 T4T3T1

FanMotor

L1

L3

L2

T2

OL

LHigh

H

LowH

A2

A1 Stop H

L C1

C2 F

R


Push Button Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2Selector Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2Switch

F RRRFF

L HHHLL

LOL HOL

T13T11 T12T3T1

FanMotor

L1

L3

L2

T2

Wiring Diagram of Three Phase Magnetic StarterTwo Speed Consequent Pole Variable Torque Motor with

Time Delay on Deceleration, Reversing Both Speeds and Push Button Control


L

H

F

R

A1 X C1 XA2 X C2 X

Run Safe Fwd Rev


CR1

28

T5T6 T4T3T1

HOLLOL

FanMotor

L L H H H

L1

L3

L2

T2

L

H H

LowStop

OL

A2

A1

H

L

H

L

H

High

CR1

CR1B2

B1Vib

Switch

A1 XA2 X

Run Safe

B1 XB2 X

Hand Off Auto

L HHHLL

LOL HOL

T13T11 T12T3T1

FanMotor

L1

L3

L2

T2

Wiring Diagram of Three Phase StarterTwo Speed Consequent Pole Variable Torque Motor with

Time Delay on DecelerationAutomatic Temperature and Push Button Control


Push Button Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2Temperature See Minneapolis Honeywell, Penn or Barber Coleman

Switch

L

H

CR1

Minimum Time DelayHigh to Low Speed - 20 Seconds


Functions@ 60F

Functions@ 40F

29

Item

Alle

n Br

adle

yCu

tler H

amm

erG

ener

al E

lect

ricSq

uare

DW

est

ingh

ouse

Star

ter

Bulle

tin 5

20Fi

le A

700

CR 3

09 F

orm

Clas

s 88

10Cl

ass

A-90

0Pu

sh B

utto

nBu

lletin

800

TFi

le E

20CR

104

P Fo

rmCl

ass

9001

Type

PB2

Tem

pera

ture

See

Min

neap

olis

Hone

ywel

l, Pe

nn o

r Bar

ber C

olem

anSw

itch

Wiri

ng D

iagr

am o

f Thr

ee P

hase

Mag

netic

Sta

rter

Two

Spee

d Co

nseq

uent

Pol

e Va

riabl

e To

rque

Mot

or w

ith T

ime

Dela

y on

Dec

eler

atio

nR

ever

sing

Low

Spe

ed w

ith T

ime

Dela

yA

utom

atic

Tem

pera

ture

and

Pus

h Bu

tton

Cont

rol

LF

Fan

Mot

or

T1T2

T3T1

3T1

2T1

1

L1 L3L2

LRLR

LRLF

LFHF

HFHF

LR

Fan

Mot

or

T1T2

T3T5

T4T6

L1 L3L2

LFLF

LFLR

LRH

FH

FH

F

HF

HF

OL

2 M

inTR

2

20 S

ecTR

3

A2A1VI

BSW

2 M

inTR

1

HF

LF

LFCR

2

CR1

C2

C1

LH

B1 B2

Low

T1T2

Stop

Hig

h

A1X

A2X

Run

Safe

B1X

B2X

Han

dO

ffAu

to

C1X

C2X

For

Rev

Not

e:If

mot

or is

sep

arat

ew

indi

ng ty

pe, u

sesa

me c

ontro

l circ

uit

but c

hang

e po

wer

circ

uit t

o th

at s

how

nbe

low.

Not

e: T1 F

unct

ions

at 6

0F

T2 F

unct

ions

at 4

0F

Min

imum

Tim

e D

elay

1.H

igh

to L

ow S

peed

- 20

Sec

onds

2.R

ever

sing

- 2

Min

utes

CR1

CR2

TR2

TR1

TR3

LF LR HF

30

HOL

T5T6 T4T3T1

LOL

FanMotor

L L H H H

L1

L3

L2

T2

L

F F R R RF

H H

LowStop

OL

A2

A1

H

L

H

L

H

High

CR1

CR1B2

B1Vib

Switch

F

R

C2

C1

H

L

B1 XB2 X

Hand Off Auto

HOL

T13T11 T12T3T1

LOL

FanMotor

L L H H H

L1

L3

L2

T2

L

R R F F FR



Push Button Bulletin 800T File E20 CR 104P Form Class 9001 Type PB2Temperature See Minneapolis Honeywell, Penn or Barber Coleman

Switch

L

L

H

CR1

F

R


A1 XA2 X

Run Safe

C1 XC2 X

For Rev

Functions@ 60F

Functions@ 40F

Wiring Diagram of Three Phase Magnetic StarterTwo Speed Consequent Pole Variable Torque Motor with Time Delay on Deceleration

Reversing Both Speeds with Time Delay Automatic Temperature and Push Button Controland 120 VAC Control Transformer

31

Wiri

ng D

iagr

am o

f Thr

ee P

hase

Mag

netic

Sta

rter

Two

Spee

d Co

nseq

uent

Pol

e Va

riabl

e To

rque

Mot

or w

ith T

ime

Dela

y on

Dec

eler

atio

nR

ever

sing

Low

Spe

ed w

ith T

ime

Dela

y, A

utom

atic

Tem

pera

ture

and

Pus

h Bu

tton

Cont

rol

Fan

Mot

or

T1T2

T3T1

3T1

2T1

1

L1 L3L2

LFLF

LFLR

LRLR

HF

HF

HF

Item

Alle

n Br

adle

yCu

tler H

amm

erG

ener

al E

lect

ricSq

uare

DW

estin

ghou

seSt

arte

rBu

lletin

520

File

A70

0CR

309

For

mCl

ass

8810

Clas

s A-

900

Push

But

ton

Bulle

tin 8

00T

File

E20

CR 1

04P

Form

Clas

s 90

01Ty

pe P

B2Se

lect

orBu

lletin

800

TFi

le E

20CR

104

P Fo

rmCl

ass

9001

Type

PB2

Switc

hPr

ogra

mSe

e Ze

nith

or A

utom

atic

Tim

ing

& Co

ntro

lsTi

mer

Min

imum

Tim

e D

elay

1.H

igh

to L

ow S

peed

- 20

Sec

onds

2.R

ever

sing

- 2

Min

utes

Fan

Mot

or

T1T2

T3T5

T6T4

L1 L3L2

LFLF

LFLR

LRLR

HF

HF

HF

HF

HF

OL

LFHF

L

2 M

inLR

2 M

inTR

1

20 S

ecH

F

A2

A1St

opVI

BSW

LF

HF

CR2

CR1C

R2High

Low

H

C1 C2

CR2

TM1

TM2

CR2

Prog

ram

Tim

er

C1X

C2X

Han

dAu

to

A1X

A2X

Run

Safe

Not

e:If

mot

or is

sep

arat

e wi

ndin

gty

pe, u

se s

ame

cont

rol

circ

uit b

ut c

hang

e po

wer

circ

uit t

o th

at s

how

n be

low.

Sugg

este

d Au

tom

atic

Reve

rsin

g Cy

cle1.

40 M

inut

es F

orwa

rd2.

20 M

inut

es R

ever

se

HF

LF LR TMCR1

TR1

CR2

32

HF

CR

1

CR

1

LF

Fan

Mot

or

T1T2

T3T5

T4T6

L1 L3L2

LRLR

LRLF

LFH

FH

FH

F

OL

2 M

inLR

20 S

ecH

F

B1VI

BSW

A1 A2

2 M

inTR

1

LF

LF

CR

2

CR

1

CR

2

LHB2

LowTM

1

TM2

Stop

CR

2

Hig

h

C1 C2

CR

1

CR

2

D1 D2

HF

HF

Wiri

ng D

iagr

am o

f Thr

ee P

hase

Mag

netic

Sta

rter

Two

Spee

d Co

nseq

uent

Pol

e Va

riabl

e To

rque

Mot

or w

ith T

ime

Dela

y on

Dec

eler

atio

nR

ever

sing

Low

Spe

ed w

ith T

ime

Dela

y, R

ever

sing

Low

Spe

ed w

ith P

rogr

am T

imer

Aut

omat

ic T

empe

ratu

re a

nd P

ush

Butto

n Co

ntro

l

LF

Fan

Mot

or

T1T2

T3T1

3T1

2T1

1

L1 L3L2

LRLR

LRLF

LFH

FH

FH

F

Not

e:If

mot

or is

sep

arat

e wi

ndin

gty

pe, u

se s

ame

cont

rol

circ

uit b

ut c

hang

e po

wer

circ

uit t

o th

at s

how

n be

low.

TM TR1

CR1

CR2

HF

LF

LR

Func

tions

@ 4

0F

Func

tions

@ 3

2F

Func

tions

@ 6

0F

Sugg

este

d Au

tom

atic

Reve

rsin

g Cy

cle1.

40 M

inut

es F

orwa

rd2.

20 M

inut

es R

ever

se

Min

imum

Tim

e D

elay

1.H

igh

to L

ow S

peed

- 20

Sec

onds

2.R

ever

sing

- 2

Min

utes

D1

XD

2X

Tim

eO

ff

A1X

A2X

Run

Safe

B1X

B2X

Han

dO

ffAu

to

C1X

C2X

Fwd

Rev

Item

Alle

n Br

adle

yCu

tler H

amm

erG

ener

al E

lect

ricSq

uare

DW

estin

ghou

seSt

arte

rBu

lletin

520

File

A70

0CR

309

For

mCl

ass

8810

Clas

s A-

900

Push

But

ton

Bulle

tin 8

00T

File

E20

CR 1

04P

Form

Clas

s 90

01Ty

pe P

B2Se

lect

orSe

e M

inne

apol

is Ho

neyw

ell,

Penn

, or B

arbe

r Col

eman

Switc

hPr

ogra

mSe

e Ze

nith

or A

utom

atic

Tim

ing

& Co

ntro

lsTi

mer

7401 W 129 Street Overland Park, KS 66213 913 664 7400www.marleyct.com email: [email protected] the interest of technological progress, all products aresubject to design and/or material change without notice.2001 Marley Cooling Technologies Printed in USA

Cooling Technologies

Control Systems Fan Motors

Documents

Transcript of Control Systems Fan Motors