Danfoss · VLT Micro Drive FC 51
The actual motor current failed to exceed the configured 'release brake' current within the specified 'start delay' time window. This indicates that the mechanical brake did not disengage as expected during the startup sequence, preventing the motor from moving.
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Manually actuate the mechanical brake (if possible) and observe its physical movement and release mechanism.
Measure the voltage supplied to the mechanical brake's coil during the release command, verifying it meets the brake's nominal voltage specification.
Verify Parameters P1-70 (Brake release current) and P1-72 (Brake start delay) are correctly configured for the specific brake and application.
With the motor decoupled from the load, attempt to rotate the shaft manually to confirm no mechanical binding (motor side).
Check the state of the digital output assigned to brake control (e.g., Terminal 29, 30) on the drive to confirm it is commanding the brake correctly.