Inrush fault

What does ALARM 33 mean?

Too many power-ups have occurred within a short time period. This can stress components due to repeated inrush currents, potentially causing premature failure of the frequency converter.

• Rapid cycling of the main power supply (e.g., main contactor) to the frequency converter due to external control system faults.
• Frequent power grid disturbances causing momentary power loss and restoration, triggering repeated inrush current events.
• Operator or automated system repeatedly powering the frequency converter off and on without adequate delay.
• Faulty or degraded pre-charge circuit components (e.g., inrush current limiting resistors, pre-charge relay) within the frequency converter.
• Incorrect parameter setting for restart delays or fault handling, allowing immediate restarts after power loss.

Click steps to track your progress.

1. 1

   1. Identify the source of repeated power cycling by monitoring the main input contactor's control signal.

2. 2

   2. Ensure a minimum off-time (e.g., 3-5 minutes) before reapplying main power to allow DC bus capacitors to fully discharge.

3. 3

   3. Monitor the incoming AC supply voltage for stability and transient interruptions using a power quality analyzer.

4. 4

   4. Verify relevant frequency converter parameters (e.g., P14-10 Mains Failure, P14-12 Auto Restart) are configured appropriately.

5. 5

   5. If accessible, inspect internal pre-charge resistors for signs of overheating or damage (e.g., discoloration, cracking).