DC overvoltage

What does 7 mean?

If the DC-link voltage exceeds a specific limit, the frequency converter will trip after a certain time delay. This typically occurs due to regenerative energy from the motor during deceleration or an issue with the mains supply.

• Excessive regenerative energy from the motor during rapid deceleration or an overhauling load (e.g., elevator descending).
• Faulty or undersized brake resistor unable to dissipate the regenerative energy (e.g., P2-13 Brake Power Monitoring set to [2] Trip).
• Brake chopper circuit malfunction (e.g., IGBT shorted or gate driver fault) preventing energy dissipation.
• Momentary or sustained high mains input voltage (e.g., >10% over nominal) causing the DC link to rise.
• Loose connection on the brake resistor terminals (e.g., 81, 82) leading to high impedance or an open circuit.

Click steps to track your progress.

1. 1

   Measure the incoming AC line-to-line voltage at the drive's input terminals (e.g., L1-L2, L2-L3, L3-L1) and confirm it is within nominal limits.

2. 2

   Increase the deceleration ramp time (e.g., P3-42 Decel Ramp Time) to allow slower dissipation of regenerative energy.

3. 3

   Measure the resistance of the external brake resistor (e.g., terminals 81, 82) and compare it to the specified value.

4. 4

   Verify that the brake chopper circuit is correctly switching by observing current flow through the brake resistor during regeneration.

5. 5

   Check parameter P2-13 (Brake Power Monitoring) and adjust to option [1] Warning if continuous operation with warning is acceptable.