Main Circuit Error

What does E25 mean?

This fault indicates a problem with the inverter's main power circuit, where the power supply establishment is not properly recognized. This can be due to electrical noise, damage to main circuit elements, or issues with the DC bus voltage sensing.

• Input power supply voltage outside the specified operating range (e.g., under-voltage below 340VDC on the DC bus).
• Excessive ripple on the DC bus due to failing DC link capacitors or a damaged rectifier bridge.
• Faulty voltage detection circuit within the inverter's main control board.
• High levels of electrical noise on the incoming AC lines affecting internal sensing circuits.
• Internal hardware damage to the main power circuit components (e.g., pre-charge resistors, contactors).

Click steps to track your progress.

1. 1

   1. Measure incoming AC supply voltage (VAC) at the inverter L1, L2, L3 terminals and confirm it is within specified tolerance (e.g., 380-480VAC ±10%).

2. 2

   2. Power down, wait for DC bus discharge, then measure DC bus voltage (VDC) between the P and N terminals; expect nominal supply voltage x 1.35 (e.g., ~540VDC for 400VAC).

3. 3

   3. Inspect power wiring for loose connections, signs of arcing, or corrosion at the input terminals (L1, L2, L3).

4. 4

   4. Verify proper grounding of the inverter chassis and associated shielding of control wiring to minimize noise ingress.

5. 5

   5. If available, use an oscilloscope to check for excessive ripple on the DC bus voltage during startup or operation, which may indicate capacitor degradation.