Under-voltage Error

What does E09 mean?

This fault occurs when the DC bus voltage inside the inverter drops below a critical threshold, indicating a control circuit fault or an unstable input power supply. This condition can also generate excessive motor heat or cause low torque, leading to an inverter trip to protect the system.

• Input AC power supply voltage sag below the inverter's specified minimum operating voltage (e.g., below 340V for 400V class).
• Loss of one or more phases in the 3-phase AC input supply (e.g., blown fuse, open circuit breaker upstream).
• Malfunction of the inverter's input rectifier bridge, preventing proper charging of the DC bus capacitors.
• Heavy transient loads connected to the same power distribution network, causing voltage dips.
• Internal failure of DC bus capacitors, reducing their energy storage capacity and causing voltage instability.

Click steps to track your progress.

1. 1

   Measure the input AC voltage across inverter terminals L1, L2, L3 using a multimeter to verify it is within specified range (e.g., 380-480V).

2. 2

   Check all fuses and circuit breakers in the upstream power supply circuit for the inverter.

3. 3

   Inspect the input power wiring for loose connections or damage at terminals L1, L2, L3.

4. 4

   Monitor the DC bus voltage (display parameter d0-02) while the inverter attempts to operate to observe the voltage drop.

5. 5

   If the problem persists and input voltage is stable, contact service as this may indicate an internal hardware fault (e.g., rectifier, capacitors).