Toshiba JKSSS Series Instruction Manual page 96

Basic Installation and Operation
Guide
7.1 Failure Analysis - Continued
Problem
Control circuit
fuses blow after
None
control power is
applied
Any fault
Motor will not start indication
message
Motor vibrates /
IMBALANCE
Motor growls while
TRIP
starting or
extremely
unbalanced motor
currents run mode
IMBALANCE
ALARM
7.1.1 - SCR Testing Procedure
Perform the SCR Heat Sink Ohm test on each Stack Assembly.
B
A
Gate Drive Board
G G K
K
White Red
Red White
TOSHIBA
CPU OLED
LED
Display
None
Trip
Trip
Alarm
Test Points
From Position A to
Position B
C
From Position B to
Position C
Gate (G) to Cathode
(K) for each SCR
Notes
1 - Allow 15 minutes after shutdown for DV/DT network to discharge.
2 - Voltage sharing resistors may need to be disconnected to obtain correct readings
for tests between positions A, B & C.
JKSSS Series Solid State Soft Starters
AUX
Possible Cause
Relay
Short in Control Circuit
None
Wrong Control Voltage
No Control Voltage applied
to Control Board
Control Power Transformer
failure or CPT Fuse failure
Start Circuit Wired
Incorrectly
No Start Command
AUX1
No 3-Phase Line Voltage
Shorted SCR in Starter
Faulty Control Logic
Failure of Main Circuit
Board
Faulty Motor
Faulty SCR(s)
AUX1
Faulty Gate / Cathode on
SCR(s)
Faulty Main Circuit Board.
Faulty Motor / Wiring
AUX2
Faulty Main Circuit Board
OHM Meter Reading
Greater than 10K Ohm
Less than 5K Ohm
Greater than 10K Ohm
Less than 5K Ohm
8 to 100 Ohms
Less than 10 or greater
than 100 Ohms
Solutions
Remove power, locate and remove
the short.
Apply the correct voltage to the
control circuit.
Apply control voltage to TB1 pins 1
and 6 on the power board.
Remove power and replace the
power transformer or the CPT
fuse.
Remove power and correct the
start circuit wiring.
Apply the start command.
Apply 3-phase line voltage to the
unit.
Remove power and Test SCR(s).
Refer to Sec. 7.1.1 for the testing
procedure.
Remove power and repair the
Control Logic.
Replace the Main Circuit Board.
Check the Motor and the Motor
connections.
Remove Power and perform the
SCR device checks.
Remove Power and Test SCR(s).
Refer to Sec. 7.1.1 for the testing
procedure.
Replace the Main Circuit Board.
Troubleshoot and repair / replace
wiring.
Replace the Main Circuit Board.
Test Results
Pass
Fail
Pass
Fail
Pass (Typical 8 to 20 Ohms)
Fail
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