Inrush Current Limit Circuit Overheat

What does E.IOH mean?

The inverter output is shut off when the resistor in the inrush current limit circuit has overheated, indicating a fault within this circuit. This typically results from frequent power ON/OFF cycles or a damaged component within the inrush current path. Continued operation with this fault risks further component damage.

• Excessively frequent power cycling (ON/OFF) of the inverter, exceeding the manufacturer's recommended power-up rate.
• Failure of the bypass contactor (if equipped) to close after the initial inrush current, leaving the inrush resistors in the main circuit.
• Damaged or degraded inrush current limiting resistors (e.g., open circuit, reduced resistance) causing increased heat generation.
• Higher-than-rated incoming line voltage or voltage surges increasing the initial inrush current magnitude.
• Insufficient ventilation around the inverter or blocked cooling fins, preventing effective heat dissipation from the inrush circuit area.

Click steps to track your progress.

1. 1

   1. Reduce the frequency of power ON/OFF cycles to the inverter (e.g., ensure minimum 10-minute interval between power-ups).

2. 2

   2. Verify the operation of the inrush bypass contactor (if present) by measuring its coil voltage and contact continuity after power-up.

3. 3

   3. Measure the resistance of the inrush current limiting resistors (requires opening the inverter, consult manual for location and value).

4. 4

   4. Check incoming AC line voltage stability (expected: within +/-10% of rated voltage) at the inverter L1, L2, L3 terminals.

5. 5

   5. Ensure ambient temperature is within specifications (e.g., < 50°C) and clear any obstructions from inverter cooling vents.