DC overvoltage

What does WARNING/ALARM 7 mean?

The DC-link voltage inside the frequency converter has exceeded its predefined limit. This often occurs during deceleration of high inertia loads, where regenerative energy is fed back into the DC link, and can lead to component damage or drive trips if not controlled.

• Deceleration ramp time (e.g., Parameter P3-02 'Ramp 1 Down') set too short for the inertia of the driven load, causing excessive regenerative energy feedback.
• Dynamic braking resistor (if installed) is incorrectly sized, disconnected, open-circuited, or its protective thermistor is tripped.
• Malfunction of the internal dynamic braking circuit (e.g., brake chopper) failing to dissipate regenerative energy.
• High or unstable incoming mains voltage causing the DC link voltage to be elevated even during normal operation (e.g., consistently above 480V for a 400V drive).
• Parameter P5-10 'DC Overvoltage Limit' set inappropriately low for the application or drive type.

Click steps to track your progress.

1. 1

   Increase the deceleration ramp time (e.g., Parameter P3-02 'Ramp 1 Down') to allow for slower energy dissipation during braking cycles.

2. 2

   Measure the resistance of the external braking resistor (if present) across terminals R+/R- and compare it to the specified value; verify wiring continuity to the drive.

3. 3

   Monitor the DC link voltage (e.g., Parameter P0-01 'DC Link Voltage') via the drive display during operation, especially during deceleration, to confirm voltage spikes.

4. 4

   Check incoming mains voltage at the drive input terminals (L1, L2, L3) to ensure it is stable and within the drive's specified operating voltage range.

5. 5

   If a braking resistor is installed and appears functional, confirm the drive's internal brake chopper (if configurable) is enabled (e.g., Parameter P5-12 'Brake Function').