Cutler-Hammer EATON Ampgard Mark V User manual

Effective 11/97
I.B. 48008
Cutler-Hammer
Instructions For Ampgard®Mark V Solid-State,
Brush-Type, Synchronous Motor Controllers
DANGER
HAZARDOUSVOLTAGE.
READ AND UNDERSTANDTHIS BOOKLET AND ITS
RELATED INSTRUCTION MATERIAL FOR FULL-
VOLTAGE CONTROLLERS INTHEIR ENTIRETY
BEFORE INSTALLING OR OPERATINGTHE
CONTROLLER.SEETABLE 1.
INSTALLATION,ADJUSTMENT,REPAIRAND
MAINTENANCE OFTHISTYPE OF EQUIPMENT MUST
BE PERFORMED BY QUALIFIED PERSONNEL. A
QUALIFIED PERSON IS ONEWHO IS FAMILIARWITH
THE CONSTRUCTION AND OPERATION OFTHIS
EQUIPMENT ANDTHE HAZARDS INVOLVED.
SYNCHRONOUSMOTORS
Polyphase synchronous motors have stators similar to
squirrel-cageinductionmotorsandmosthaverotorswith
DC slip-ring circuits which must be energized for normal
operation. The controller described in this booklet is for a
synchronous motor with slip rings and brushes.
Synchronousmotorsoperate at constant base speeds
correspondingtolinefrequencyandthe number of ma-
chine poles (revolutions/min = 120 x frequency/number of
poles). They are employed primarily to obtain high pullout
torques,constantoperatingspeeds, or generation of
leading reactiveVA (VAR) for system power-factor correc-
tion. Theyrequire conventionalACpolyphase power
sources for their stators and suitable DC power sources
fortheirrotorfields.
Fornormaloperation,synchronousmotorsmustbe
brought to near full operating speed, at which point the DC
powerisconnected to the rotating field through brushes
and slip rings. The motors are accelerated to their syn-
chronizing speeds by means of either built-in start wind-
ings or external auxiliary drives. Nearly all conventional
synchronousmotorsnow manufactured have built-in rotor
starting windings. Such starting windings are also referred
toassquirrel-cage windings, pole-face windings, damper
windings, or amortisseur windings. Start windings are
actually squirrel-cage induction bars located in the faces
TABLE I. REFERENCE MATERIAL
Contactor Ampere Instruction
Type Rating I.L. or I.B.
Type SJA 360A I.B. 48002
Type SJA 720A I.B. 48005
Type SJD 360A I.B. 48004
Type SJO 360A I.L.16-200-33
Type SJO 720A I.L. 17047
Type SJS 360A I.B. 48003
of the DC rotor poles. They produce accelerating torque
only and have short-time intermittent duty ratings. As
start windings, they become inoperative at synchronous
speeds but serve to dampen any tendency of the rotor to
oscillate in angular position with relation to the stator field.
The starting of synchronous motors involves two basic
switching functions. The first is the energizing of the
statortoproducebreakaway torque and acceleration to
near synchronous speed, the second is the energizing of
the DC rotor field at the optimum speed and rotor-stator
pole relationship. For motors having built-in start wind-
ings,thesameequipmentconsiderationsare required as
for full-voltageor reduced-voltagestartingmethodsused
for squirrel-cage induction motors. All factors relating to
the stator circuits are identical.
Synchronousmotors have two torque characteristics,
startingtorqueandrunning or synchronous torque. The
first is determined by the squirrel-cage design and the
“slip” as the motor accelerates from zero to near synchro-
nous speed. “Slip” is expressed as a percent fraction
wherethenumeratoristhedifferencebetweenthesyn-
chronousspeedand the non-synchronous speed, and the
denominator is the base speed, all speeds expressed in
revolution perminute(rpm). The running torque character-
istic (at synchronous speed) is produced by the magnetic
fields created by the DC field coils in the rotor which link
with the rotating fields produced by the AC current in the
stator windings. See Figure 1.
The DC field coils are energized via two slip rings and
brushes. The DC voltage applied to the field coils can be
varied to produce the desired level of direct current which
in turn produces a magnetic field through each pole which
can be varied. Once at synchronous speed,

I.B. 48008
Page 2
Effective 11/97
SYNCHRONOUSMOTORS(Continued)
changing the field current can change the power factor at
which the synchronous motor runs or the reactive current
drawnfromtheACline.
A synchronous motor cannot start with its DC pole
windings excited. Voltage is applied to the DC winding
only after the motor has been accelerated to a speed
which is over 90 percent of synchronous speed. With a
slip of less than ten percent, the DC poles will jump to
synchronousspeedwhenDCvoltageisappliedandwill
lock onto the rotating magnetic field produced by the
three-phasealternatingcurrentin the stator.
Applying DC at the most advantageous time is the job of
the motor controller which uses feedback signals to opti-
mize the transition and thereby minimize the disturbance to
the power system at the time of synchronization.
MOTOR FIELD EXCITATION
In this controller, the DC power for the excitation of a
synchronous motor field is obtained from a solid-state
power supply (exciter). Provisions are made for field
current adjustments. Usually, field current is set to
optimum values only after the motor field has reached
maximum operating temperatures. On cold start-ups, the
field current may be 20 to 40% high initially but will
decreasetonormal as operating temperatures are
reached. The field current is usually maintained as set
duringmotoroperation except where the field current
regulator option is included for those applications in which
VAR, power factor, or the field current itself is being
automaticallyadjusted.
THEMOTOR CONTROLLER
As explained in the companion instruction material, each
Ampgard®full-voltage motor starter (controller) consists of
onenonload-breakisolatingswitch,one contactor, current-
limiting fuses, a set of current transformers, and some
form of overload protection. A reduced-voltage starter
includes all of the components of a full-voltage starter plus
oneortwoadditionalcontactorsandrelatedcontrol
components. A synchronous motor controller is either a
full-voltagestarter or a reduced-voltagestarter which
includes a source of DC and the additional controls
needed to start a synchronous motor, operate it at syn-
chronous speed, and protect it.
THE MARKV CONTROLLER
The MarkV is a field power supply and controller that
blocksthefieldvoltageduringsubsynchronous operation
andappliesthe field voltage during synchronous operation.
The field voltage is adjusted by a potentiometer during
operation.
Fig. 1 Synchronous Motor Components
This solid-state field power source functions without
regardtothe phase sequence of the three-phase power
supply, which may be at either 50 or 60 hertz. The field
powersupplyandcontroller contains synchronizing
circuitry with means to adjust the synchronizing slip-
frequency from 1 to 9 percent (SW1) and the permissible
stalled-rotor time from 0 to 9 seconds (SW2). It has pole
slippagesensing,incompletesequence detection and
shutdown in the case of exciter low voltage or phase loss.
Figure 2 shows the solid-state field power supply panel
designed to control the application of either 125VDC or
250VDC to the field of a synchronous motor. The panel
consists of a printed circuit board (synchronizing control
board), protective fuses, and an assembly of power
thyristors (silicon controlled rectifiers, SCR’s) arranged to
convert 120 or 240VAC, three-phase, to 125 or 250VDC,
respectively. The direct current (DC) is supplied directly to
the field of the synchronous motor. The synchronizing
control board shown in the lower portion of Figure 2
appearsenlarged in Figure 3.
Characteristics
Each Mark V controller has a maximum DC current
capability (50, 100, or 200 amperes), a rated field supply
voltage of 125 or 250VDC, and the ability to withstand a
field output (induced) voltage of up to 1500 volts during
the time that the motor is coming up to rated speed, i.e.,

I.B. 48008 Page 3
Effective 11/97
the field has not yet been energized by the DC power
supply, or the converse, the motor coasting to a stop with
thefielddeenergized.
Thecontrollerprotective functions include:
1. Locked-rotorprotection
2. Incomplete-sequenceprotection
3. Failure-to-synchronizeprotection
4. Loss-of-synchronization(pull-out) protection
5. Open-phaseprotection
6. DC loss (field loss) protection
Automatic power factor regulation is not included with the
standard unit, but is available as an option.
Functions
MarkV controllers for synchronous motors consist of the
basic components shown in Figure 4. Their functions are
as follows:
The line contactor (M) operates to connect the motor to
theACline. Additionalcontactorsarerequiredinreduced-
voltage starters to short out the reactor or to connect and
disconnect the autotransformer in the circuit.
Theoverloadprotectionrelay(e.g.,IQ1000-II)protectsthe
motorfromdamagebyovercurrentconditions,single
phasing,orotherabnormalconditionssuchasphase
reversal or ground fault. It operates to trip the line
contactor M.
The starting and field-discharge resistor (S/D RES) is
used to improve the motor starting torque and to limit the
induced field voltage during starting or when the field
excitation is removed. The resistor current and ohmic
values are determinedbythe motor designer. Themotor
controller is designed to operate motors with less than
1,500 volts rms in the field during starting. The current
flowing to the resistor is controlled by diode D1 and SCR
Q4 (Fig.4). Voltage feedback (VR on the synchronizing
controlboard)providesinformation about the induced field
voltage,frequency, and phaseangle.
Fig.2 Mark V Field Power Supply Panel
Fig. 3 Synchronizing Control Board

I.B. 48008
Page 4
Effective 11/97
MarkV Controller Functions (Cont.)
The SCR field power supply QA1, QB1, QC1, QA2, QB2,
andQC2suppliesvoltage(125 or 250VDC) and current to
the motor field. The power supply comes in three sizes,
50,100,or200amperesDC.
The printed circuit board provides gating signals for the
starting and discharge circuit and protective functions as
well as the SCR power supply.
Thefield power transformer must have either a 120or 240
volt three-phase AC secondary. A 120 volt AC secondary
is required for the 125VDC system. A supply of 240 volts
AC is required for the 250VDC system. It may be con-
nected wye or delta. Do not ground the system. The
transformer is sized KVA = .17 x rated amps DC @ 125
volts DC or KVA = .34 x rated amps DC @ 250 volts DC.
Currenttransformers arefurnished inthemotorstarter
(controller) to supply current to protective relays and
various meters in direct proportion to the line current.
CONTROLLEROPERATION
Figure 4 shows the field power supply controller in con-
junction with the motor controller for a synchronous motor
starter. Note that the connection to the field supply
transformer is between the contactor (M) and the IQ
component so that the current transformers sense motor
stator current only.
The field power supply controller consists of three types of
circuits, one each dedicated to (1) field power, (2) control,
and (3) motor starting. The six thyristors (SCR’s), QA1
throughQC2,arethemaincomponentsofthefield power
circuit. The control circuit controls the starting circuit and
the output of the field power circuit.
A motor start sequence is initiated by closing the line
contactor (M). This results in the motor stator and the
solid-statefieldpowersupply being energized.
On start-up, three-phase voltage signals are supplied to
terminals KA2, KB2, and KC2. The open-fuse detection
circuit requires about 100 milliseconds to determine that
all voltages are present. It then causes RLY1 to close the
circuitbetweenterminals ST1 and ST2 onTB1 (Figure 5).
The light emitting diode, LED1 is lit. If any fuse opens
and voltage is lost at terminals KA2, KB2, or KC2, RLY1
will drop out to open the control circuit.
RLY1andRLY3maypulse open andclosedduringcertain
types of faults causing the interposing relay “MX” to drop
out,insuring that the“M”contactor hasdroppedout.SYTR
remainsenergizeduntil “M”dropsout.
The motor starter, being energized, causes the motor field
to generate an output voltage at the instantaneous slip
frequency of the motor. This voltage is controlled by the
independentlyoperatingthyristor-controlled startingcircuit
D1-Q4.
The voltage across the field starting and discharge
resistor (S/D RES) is monitored during the starting
sequencetodeterminetheinstantaneousslipofthemotor.
A motor slip condition of less than 75% (more than 25%
speed) must be reached within the preset time (rotary
switch SW2), ranging from 0 to 9 seconds, or a stalled
rotorcondition will be indicated by the incomplete-se-
quencerelay(RLY3)being energized.
As the motor continues to accelerate and the motor slip
frequency becomes less than the level established by the
setting of rotary switch SW1 (0-9%), the gate drives to the
field power supply thyristors activate and the soft turn-on
circuit begins to apply DC voltage to the motor field. If the
motor does not synchronize, Q4 is gated on. At the same
time gating to QA1 - QC2 is inhibited until Q4 stops
conducting.
Once again QA1-QC2 is gated on, applying voltage to the
motor field. This process is repeated until the motor
synchronizes or until a fixed time in the range of 2.5 to 3.5
secondselapses.
Should the motor continue to slip poles after the 2.5 to 3.5
second period has elapsed, as indicated by the starting
circuit thyristor (Q4) continuing to conduct, the incom-
plete-sequencerelay(RLY3)will be energizedindicatinga
failure to synchronize.
If the motor fails to reach the expected slip frequency
within 34 or 40 seconds from the beginning of the start
sequence,the timeout (TO)function will operateand the
incomplete-sequencerelay(RLY3) willagainbeenergized
if this option is chosen (by inserting jumper TO). See
OPTIONS onPage 6.
Whenmotor synchronizationisbeing established,the
output voltage is sensed and regulation of the field voltage
isaccomplishedbyappropriatecontrolof the gating
patternstothe field power supply thyristors QA1-QC2.

I.B. 48008 Page 5
Effective 11/97
The minimum output voltage can be adjusted from 50% to
70% of nominal voltage (125 or 250VDC) with a potenti-
ometer(P1)ontheprinted circuit board. See Figure 5.
Full voltage control is achieved by the addition of a
potentiometer (P2), typically mounted on the front panel of
the power supply cabinet. The range of local voltage
control adjustment is coordinated with the minimum output
voltageadjustment(P1)toproducethedesiredminimum
and maximum output voltages.
Fig. 4 Mark V Controller Schematic
When the motor is running at rated speed and the line
contactor (M) opens, the gating must be inhibited to SCRs
QA1 to QC2. To do this, voltage is removed from terminal
115andIN-.
If gating is not inhibited, the motor will continue to supply
excitation voltage until it slows to about 50% speed.

I.B. 48008
Page 6
Effective 11/97
OPTIONS
Each of the six variations rated by field supply output
currentandvoltage(50,100,or200amperesat either
125or 250VDC) willperform with any combination of
user selected options as determined by jumpers inserted
into terminals on the synchronous control board. See
Figure 5 andTable II.
Supply Frequency
The synchronizing and control circuit board may be
operated from either a 50 or 60 hertz power supply. To
operatefrom a 60hertz powersupply add threejumpers
to the 60 hertz terminals located near RLY1 and one
jumper to the 60 hertz terminal located near RLY3. See
Figure 5 andTable II.
To operate from a 50 hertz supply remove all four jump-
ers from the 60 hertz terminals and add a single jumper
to the 50 hertz terminal located near RLY3. See Figure 5
andTable II.
110/120VAC Operation
To operatethesynchronizingandcontrolcircuitboard
from a 110 or 120VAC supply, add six jumpers to
the120V terminals located aboveT1,T2, andT3 and two
jumpers to the 120V terminals located nearT4. Remove
thejumper from the 240V terminal located withTO
terminal nearT4. See Figure 5 and Table II. (Jumpers
are factory installed, when supplied as part of a complete
motorstarter.)
220/240VAC Operation
To operatethesynchronizingandcontrolcircuitboard
from a 220 or 240VAC supply, add three jumpers to the
240V terminals above T1,T2, and T3 and one terminal to
the240VterminallocatedwiththeTOterminalnearT4.
Removejumpers from the two 120V terminalslocated
nearT4. See Figure 5 andTable II.
ADJUSTINGTHE MOTOR FIELDVOLTAGE
To adjust the motor field voltage, use the external 2000
ohmpotentiometer(P2)shownin Figure 4.
POWER FACTOR,VAR OR DC FIELD CURRENT
CONTROL(OPTION)
When this option is included, a two-position selector
switch marked AUTO-MAN (SS1) is furnished. On initial
startup, place SS1 in the MAN (manual) position. I.B.
48009explainstheautomaticoperation and the connec-
tion of this additional control panel to terminalsVPF and
PSConthesynchronouscontrolboard(Figure5).
INCOMPLETE SEQUENCE –TIME-OUT SHUTDOWN
To utilize the time-out (TO) option which will energize
control relay RLY3, place a jumper onto the two pins
markedTO in the four-pin terminal marked240V,TO
located to the right of RLY3 on the printed circuit board.
With theTO jumper in place, RLY3 is energized whenever
the motor slip frequency fails to decrease to the synchro-
nizing slip frequency set by SW1 within a period of 34
seconds when operating at 60 hertz or 40 seconds when
operating at 50 hertz.
TABLE II — JUMPER INSTALLATION FOR OPTIONS
FUNCTION TERMINAL MARKING PUT JUMPER JUMPERS NEEDED
AT TERMINALS TO ACTIVATE
Use a 50 Hertz Supply 50 HZ, 60 HZ 50 HZ 1
60 HZ, 60 HZ, 60 HZ None 0
Use a 60 Hertz Supply 50 HZ, 60 HZ 60 HZ 1
60 HZ, 60 HZ, 60 HZ 60 HZ, 60 HZ, 60 HZ 3
Use a 110 or 120 VAC 240V, TO None 0
Supply 120 V, 120V 120 V, 120 V 2
(3) 120 V, 240 V, 120 V (3) 120 V, 120 V 6
Use a 220 or 240 VAC 240 V, TO 240 V 1
Supply 120 V, 120 V None 0
(3) 120 V, 240 V, 120 V (3) 240 V 3
Time-Out Shutdown 240 V, TO TO 1

I.B. 48008 Page 7
Effective 11/97
EXTERNAL INHIBIT
Ifthecontrollercontainsanautotransformerforreduced-
voltage starting, DC voltage will not be applied until after
transition to full voltage. Synchronization is blocked by
withholding115VACfromterminals 115 and IN-. When
voltage is applied to terminals 115 and IN-, the MarkV will
go into the synchronizing mode.
SYSTEM PROTECTION
This controller includes circuits that provide a means of
shutting down in the event of a stalled motor, excessive
start time (time-out periodexceeded),or pole slippage
after synchronization. Where the protection system
consists of contacts in a control circuit, use the normally-
closed (NC) contacts of RLY3 to open the
Fig. 5 Synchronous Control Board Layout

I.B. 48008
Page 8
Effective 11/97
SYSTEM PROTECTION (Continued)
circuit. These contacts are available at terminals SQ1 and
SQ2 ofTerminal Board 1 (TB1). See Figure 6.
RLY1(seeFigure6)becomesenergized about 50 millisec-
onds after power is delivered to the printed circuit board
andproper operational status of the controller is estab-
lished. RLY1 and its associated Light Emitting Diode
(LED1)remainenergizedas long as the built-in+15VDC
voltagesourceremainsaboveaprescribedleveland
three-phasepowerto the controller is present. The
normally-open(NO)contactsofRLY1 should be used in
series with the control circuit. Thus loss of control power
will result in shutdown of the motor.
ROTARY SWITCH SETTINGS
Rotary Switch 1 (SW1) is a ten-position selector switch
which determines the percent slip (1 to 9%) at which the
controller is to apply DC power to the synchronous motor
field to begin synchronization. Unless experience with a
particular motor suggests otherwise, set SW1 at 5%.
Rotary Switch 2 (SW2) is a ten-position selector switch
whichdeterminestheperiod(0to9seconds)duringwhich
the motor must accelerate to a slip condition of 75% or
less. If the motor does not accelerate to the 75% slip or
less within the set time period, a stalled rotor condition is
presumed to exist and the incomplete sequence relay
(RLY3) willbeenergized. Unlessexperiencewith a
particular motor and its load suggests otherwise set SW2
at 5 seconds.
STARTWINDING PROTECTION
The most critical protection for synchronous motors is that
for the windings used to start the motors. These windings
are short-time rated for starting duty only and are most
vulnerableunderlocked-rotor conditions. Optimum
protection provides for stall protection while still permitting
slipprotection. Squirrel-cagebarprotection is required on
motorstart-upwhileensuringthatpropersequential
synchronizing occurs and that motors will operate continu-
ously in synchronism. The protection system must detect
andoperatefor a condition of prolonged subsynchronous
operation beyond the thermal capability of the starting
windings. SeeFigure7.
Once synchronous motors have been initially and suc-
cessfully synchronized, loss of synchronism or pullout is
detected by the presence of induced slip current or AC
voltage superimposed on the DC excitation source. In
brush type controllers, the same system used for field
applicationisalsoemployedforpulloutprotectionwhere
field sensing is used for both functions.
Fig. 6 Control Relay Terminals
Because of the vulnerability of synchronous motors, the
best practice is to provide for immediate shutdown on
pullout except for those installations where positive
protection against all combinations of operating hazards is
assured.
MOTOR OPERATING HAZARDS
Someofthemajoroperatinghazardsforsynchronous
motors are operating abuse, low line voltage, low excita-
tion current, and excessive shaft load. The pullout torque
capabilities of synchronous motors are a function of stator
andfieldpower. Supplementary protection forsynchro-
nous motors may be provided through the use of field
voltageandcurrentrelaysandstatorfrequencyrelays.
Extreme care must be exercised, especially with large
synchronous motors, if attempts are made to reconnect
motorstotheline after momentary power interruption.
Reconnection of line voltage that is substantially out of
phasewithopen-circuitmotor terminal voltage can result
inextremelyhighcurrent and torque surges capable of
creatingsystemdisturbancesand mechanical damage.
Additionalhazardsforsynchronousmotors are jogging,
too frequent starting, stalling and excessive accelerating
times. Any of these conditions are serious hazards to
start windings. Even the best protective system may not
protectundersuchextremeoperating conditions.

I.B. 48008 Page 9
Effective 11/97
AUTOTRANSFORMER STARTEROPERATION
The field power thyristors will be held OFF until the 115
VAC inhibit signal and the proper slip frequency have
appeared. The2.5to3.5secondsynchronizingperiod
also will not start until both these conditions are met.
When the controller is used in conjunction with a
reduced-voltagemotorcontroller, the gating is inhibited
until full voltage is applied to the motor. This is done by
not applying 115 volts to terminal 115 and IN- on the
circuit board, until motor is at full voltage.
The field excitation must not be applied until an
autotransformerstarter has been sequenced to full
voltage. If the field is applied before the starter has
transitioned to full voltage, a high current will result from
the voltage unbalance condition, and may cause physical
damage.
START-UP PROCEDURE FOR AMPGARD LINE-UP
Prior to start-up, verify a proper line-up installation, one
that is undamaged, free of skids, eyebolts, lifting angles,
debris, and all foreign material, one that is level and
securelymountedand properly wired. Confirm each
starter compatability with motor voltage, HP, and FLA.
Check the torque tightness of all connections. Study all
applicableinstructionmaterialand diagrams. Have
availabletheschematicandconnectiondiagramsfur-
nishedwiththe following equipment:
1. Dielectric(Hi-pot)testercapableofdelivering40
milliamps at 16 kVAC or 23 kVDC.
2. Multimeter to measure ohms and DC volts.
3. Meg-ohmmeter (Megger) capableofproducing 2500
volts.
SafetyCheck
Verifythat the primary (medium-voltage)sourcesofpower
to the Ampgard bus system are disconnected and locked
out.
Fuse and Contactor Check
1. Remove power circuit fuses and contactor from each
enclosure.
2. Removecontrol transformer primary fuses from each
contactor.
3. Use ohmmeter to verify continuity of fuses.
4. Check contactor and Hi-pot 16 kVAC or 23 kVDC
across each bottle for 1 minute. 5ma leakage is
failure.
Bus System Check
With the contactors and power circuit fuses removed,
preparetheline-upforameggertest:
1. Close each isolating switch.
2. Disconnectmetering taps,capacitors,arrestorsand
any other equipment connected to the bus bar sys-
tem.
3. Thenmeasureand record the megohm resistance
between phases of the bus bar system and between
each phase and ground. Track down and correct any
sourceof a low reading.
Fig. 7 Thermal Capacity of a Typical Synchronous Motor
Start Winding

I.B. 48008
Page 10
Effective 11/97
Synchronous Motor Check
Each MarkV synchronous motor controller has a terminal
strip consisting of seven studs on standoff insulators
mountedonasubpanelandlabeledas shown in Figure 8.
Disconnect leads from these stabs as necessary to
conduct the following tests:
1. With the motor slip rings clean and brushes down (in
operatingposition)measure and record the cold motor
field resistance between F1 and F2. Calculate the
field resistance by dividing the nameplate field voltage
by the nameplate field current. The measured ohms
shouldbebetween70and80percentofcalculated
ohms. If the measured resistance at the terminal strip
(F1 and F2) is more than 80 percent of calculated
resistance measure the field resistance at the motor
slip rings. This latter reading should be less than the
previous reading. If resistance readings are still high
determinecause.
2. With the motor field disconnected verify that the
resistance between F1 and F2 on the terminal strip is
250 ohms, + 15 ohms.
3. Measure the resistance of the starting and discharge
resistor (S/D RES on schematic diagram, Figure 4) at
terminals R1 to R3 on the terminal strip (Figure 8).
The measured value should be as shown on the
diagramaccompanyingtheorder. Measurethe
resistance between terminalsVR and KA1 on the
synchronouscontrolboard (CB). The reading should
be 50 ohms + R1-R3 value.
4. Reconnectallleads.
Controller Check
1. Verify that the jumpers required for the installation are
properly installed. SeeTable II.
2. Read the ampere ratings of the three fuses supplied
on the secondary side of the transformers providing
power to thesolid-statecontroller.
These fuse ratings are equal to the ampere rating of
the field power supply.
3. Verify the dial setting of the FLA relay located adja-
cent to the synchronous control board (Fig.3). This
dial setting should equal 40% of the motor nameplate
field current divided by the ampere rating of the field
powersupply.
Fig. 8 Cubicle Terminal Strip