ALARM 7

DC overvoltage

Danfoss · VLT HVAC Drive High Power

What does ALARM 7 mean?

The DC-link voltage has exceeded its limit, causing the frequency converter to trip after a certain time. This often occurs due to regenerative braking or excessive mains voltage, which can damage the inverter section if not mitigated.

Complete Troubleshooting Guide

  1. 1

    Connect a brake resistor to dissipate excess energy.

  2. 2

    Extend the ramp-down time to reduce regenerative energy.

  3. 3

    Change the ramp type to a softer deceleration profile.

  4. 4

    Activate appropriate functions in parameter 2-10 Brake Function.

  5. 5

    Increase parameter 14-26 Trip Delay at Inverter Fault.

Source: Danfoss Manual