DC link overvoltage

What does F-07 mean?

The DC link voltage within the inverter has risen above safe operating limits, triggering an immediate shutdown with inhibit. This is typically caused by excessive regenerative energy from the motor during deceleration, an issue with the braking resistor, or a ground fault. Persistent overvoltage can damage the inverter's power stage.

• Rapid deceleration of a high inertia load where regenerative energy exceeds the inverter's capacity or external braking resistor capability.
• Braking resistor open circuit, incorrect sizing (resistance too high), or shorted wiring preventing dissipation of regenerative energy.
• Braking chopper circuit failure, preventing it from switching on to dissipate energy through the braking resistor.
• Input supply voltage too high (e.g., consistently above 480V for a 400V class inverter), causing the DC link voltage to exceed its nominal rectified peak.
• Motor output short circuit or ground fault condition causing uncontrolled energy feedback into the DC link.

Click steps to track your progress.

1. 1

   Measure the resistance of the external braking resistor (e.g., terminals DB+/DB-) to confirm it matches the specified value (e.g., 20 ohms).

2. 2

   Increase the deceleration time parameter (e.g., P1-30, P0-21) to allow for slower energy return to the DC bus.

3. 3

   Verify the braking chopper function by observing voltage across the braking resistor during deceleration or checking diagnostic parameters (e.g., P0-96 status).

4. 4

   Measure incoming AC supply voltage (L1-L2, L2-L3, L3-L1) to ensure it is consistently within the inverter's specified input voltage range.

5. 5

   Check for any short circuits or ground faults on the motor output cables and within the motor windings themselves.