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JKSSS+ Series
Problem
CPU LCD Display
Any fault indication
Motor will not start
message
Motor vibrates/
Motor growls
while starting or
IMBALANCE TRIP
extremely
IMBALANCE ALARM
unbalanced motor
currents run mode
7.1.1 - SCR Testing Procedure
Perform the SCR Heat Sink Ohm test on each Stack Assembly.
A
Gate Drive
Board
K = Cathode = Red Wire
G = Gate = White Wire
JKSSS+ Series - 82
Aux
LED
Relay
Trip
AUX1
Trip
AUX1
Alarm
AUX2
Test To Perform
From Position A to
Position B
C
From Position B to
Position C
Gate (G) to Cathode
(K) for each SCR
B
Note: Allow 15 minutes after shutdown for DV/DT network to discharge DC
voltage.
Possible Cause
No control voltage applied
Apply control voltage to TB1 pins 1 and 6
to control board
on the power board
Control power transformer
Remove power and replace the power
failure or CPT fuse failure
transformer or the CPT fuse
Start circuit wired
Remove power and correct the start
incorrectly
circuit wiring
No start command
Apply the start command
No 3 phase line voltage
Apply 3 phase line voltage to the unit
Remove power and test SCR(s). Refer to
Shorted SCR in starter
Section 7.1.1 for the SCR testing
procedure
Remove power and repair the control
Faulty control logic
logic.
Failure of main circuit
Replace the main circuit board
board
Check the motor and the motor
Faulty motor
connections
Remove power and perform the SCR
Faulty SCRs
device checks
Remove power and test SCR(s). Refer to
Faulty gate/cathode on
Section 7.1.1 for the SCR testing
SCRs
procedure
Faulty main circuit board
Replace the main circuit board
Faulty motor/wiring
Troubleshoot and repair/replace wiring
Faulty main circuit board
Replace the main circuit board
Ohm Meter Reading
Greater than 10K Ohm
Less than 10K Ohm
Greater than 10K Ohm
Less than 10K Ohm
8 to 100 Ohms
Less than 10 or greater than 100 Ohms
2.3 - 4.2KV
Solutions
Test Result
Pass
Fail
Pass
Fail
Pass (Typical 8 to 20
Ohms)
Fail
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