Fault Diagnosis - AuCom CSX-007 Service Manual

TROUBLESHOOTING
• If the bypass relay does not close, the bypass relay, Main Control PCB or Interface PCB may be faulty, or
there may be a faulty connection between these components. To isolate the fault, perform the bypass
relay integrity test.
4. When the soft starter is running, measure the voltage across L1-T1 and L3-T3. This should be less than 0.5 VAC.
• If the voltage remains near nominal mains voltage, the bypass relay did not close. This can be caused by
a faulty relay, faulty Main Control PCB, a faulty Interface PCB, or a poor connection between these two
PCBs. To isolate the fault, perform the bypass relay integrity test.
5. Command the soft starter to stop. You should hear the bypass relay open.
• If the bypass relay does not open, perform the bypass relay integrity test.
2.2

Fault Diagnosis

PCB Integrity Test
This procedure further isolates a fault with the soft starter's control circuitry.
1. Verify that the connection between the Main Control PCB and the Interface PCB is sound.
•
remove and refit the Main Control PCB
•
check whether the soft starter now operates correctly
2. Verify that the Main Control PCB is sound
• remove and replace the Main Control PCB
•
check whether the soft starter now operates correctly
3. Verify that the Interface PCB is sound
•
refit the original Main Control PCB
•
remove and replace the Interface PCB
•
check whether the soft starter now operates correctly
If the fault cannot be traced to either the Main Control PCB or the Interface PCB, replace both PCBs.
Bypass Relay Integrity Test
This procedure further isolates a fault with the soft starter's bypass circuitry.
1. Verify that the connections between the Main Control PCB and the Interface PCB, and between the Interface
PCB and the bypass relay are sound.
•
remove the Main Control PCB
•
remove the Interface PCB
•
refit the Interface PCB to the bypass relays
•
refit the Main Control PCB
•
check whether the soft starter now operates correctly
2. Verify that the bypass relay is sound
• remove the Main Control PCB and Interface PCB
• momentarily apply 24 VDC to the bypass relay control pins. The bypass relay should change state. The
bypass relays are latching, so behaviour must be checked by applying voltage in both directions.
If the bypass relay does not change state correctly, it must be replaced.
Figure 1: Bypass relay control pins (7 kW ~ 30 kW models)
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