DC link overvoltage

What does F07 mean?

The DC link voltage has exceeded its switch-off threshold, typically due to excessive regenerative power from the motor (e.g., during deceleration) when no braking resistor is connected or if deceleration ramps are too short. This can damage the inverter's power stage and other components if sustained.

• Excessive regenerative power from the motor during deceleration (e.g., high inertia load, short ramp time P1-09).
• Braking resistor either disconnected, faulty (e.g., open circuit detected by resistance measurement), or undersized for the application.
• Deceleration ramp time (e.g., P1-09) set too short, causing rapid kinetic energy conversion back into the DC link.
• Main supply voltage exceeding the nominal input voltage range (e.g., >480VAC for a 400V nominal drive).
• Faulty DC link voltage measurement circuit within the inverter, providing an erroneous high voltage reading.

Click steps to track your progress.

1. 1

   1. Monitor DC link voltage (e.g., via parameter P0-01) during deceleration and verify it exceeds the specified trip threshold (e.g., 820V for a 400V drive).

2. 2

   2. Measure the resistance of the braking resistor (e.g., at terminals X17/BR) and compare to its nameplate value (e.g., 50 Ohms +/-10%).

3. 3

   3. Increase deceleration ramp time (e.g., P1-09) by 20-50% and re-test motor stopping behavior.

4. 4

   4. Measure incoming AC supply voltage at the inverter's input terminals (L1, L2, L3) to ensure it's within tolerance (e.g., 400VAC +/-10%).

5. 5

   5. If no external braking resistor is used, consider installing one with appropriate resistance and power rating for the application to dissipate regenerative energy.