Danfoss · VLT Micro Drive FC 51
The inverter's peak current limit has been exceeded, indicating a sudden and excessive surge in current. This is a critical fault often caused by a short circuit in the motor or its cabling, or an extremely sudden and heavy load application, which can damage the drive's output stage.
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Disconnect the motor cables from the drive's output terminals (U, V, W) and power cycle the drive to see if the fault clears.
Perform an insulation resistance test on the motor cables from each phase (U, V, W) to ground and between phases, expecting >1 Megaohm.
Measure the resistance between each motor phase (U-V, V-W, U-W) at the motor terminals, verifying they are balanced and within expected values (e.g., <1 Ohm for large motors).
Increase the acceleration ramp time (P1-02) if the fault occurs during startup, to reduce inrush current.
Check for mechanical binding or seizure in the driven equipment that could cause an immediate high current draw.