Inrush Current Limit Circuit Fault

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This fault occurs when the resistor within the inverter's inrush current limit circuit overheats. This typically happens due to frequent power ON/OFF cycles to the inverter, stressing the charging components, or an internal component failure. Prolonged overheating can damage the inverter's power supply section and lead to critical failures.

• Excessive frequency of main power ON/OFF cycles to the inverter's input (R/L1, S/L2, T/L3), preventing proper discharge of the DC bus.
• External input contactor or circuit breaker being cycled too rapidly, engaging the pre-charge circuit repeatedly.
• Failure of the main DC bus charging contactor (if present) to close properly after the pre-charge sequence, leaving the inrush resistor in circuit.
• Deterioration or failure of the inrush current limiting resistor itself due to thermal stress or aging.
• Overvoltage condition on the input power supply, increasing the charging current and thermal load on the resistor.

Klikk på steg for å spore fremgangen.

1. 1

   Reduce the frequency of power cycling the main input power to the inverter; allow at least 10 minutes between power ON cycles.

2. 2

   Verify the proper operation and timing of the external input contactor, ensuring it closes only after the DC bus voltage stabilizes.

3. 3

   Check the DC bus voltage at terminals P/+ and N/- immediately after power-up; it should rise steadily to the nominal level (e.g., 540VDC for 400VAC input).

4. 4

   Visually inspect the inrush current limiting resistor (often a large ceramic component) for signs of overheating, charring, or cracking.

5. 5

   Use a multimeter to measure the input voltage (R/L1, S/L2, T/L3) to ensure it is within the inverter's specified operating range (e.g., 400V ±10%).