24V external power supply operation

What does EV mean?

This indication flickers when the inverter is being powered by the 24V external power supply, but the main circuit power is not supplied. It serves as an alarm, informing the technician that the main power source is absent or insufficient, although the inverter itself is not tripped. This can prevent unexpected startup when main power is restored.

• Main circuit breaker or disconnect switch for the inverter is open or tripped, preventing input power (R, S, T) from reaching the main rectifier.
• Loss of one or more phases on the incoming AC supply to the inverter's main terminals (R, S, T).
• Blown fuse(s) in the main AC input line to the inverter, preventing the main circuit from energizing.
• Internal pre-charge circuit fault in the inverter, preventing the DC bus from charging when main power is applied.
• Incorrect wiring or loose connection on the main power input terminals (R, S, T) of the inverter.

Click steps to track your progress.

1. 1

   1. Verify that the main circuit breaker supplying power to the inverter is closed and not tripped. Reset if necessary.

2. 2

   2. Measure the voltage across each phase of the incoming AC supply at the inverter's R, S, T input terminals (e.g., R-S, S-T, T-R) to confirm balanced and correct line voltage (e.g., 480VAC).

3. 3

   3. Inspect and test the main input fuses (if external) or internal fuses (if accessible and safe to do so) for continuity using a multimeter. Replace any blown fuses with the correct rating.

4. 4

   4. Check for loose connections or damaged wiring on the main power input terminals (R, S, T) of the inverter. Tighten all terminal screws to specification.

5. 5

   5. If the inverter has an external 24VDC supply for control, confirm it is present at the designated terminals (e.g., P24, N24) and stable, while simultaneously verifying absence of main AC power.