Output Short Circuit

What does OC1 mean?

A short circuit has been detected on the drive's output, possibly in the motor, motor cables, or brake resistor circuit. Excessive capacitive charging current from long or high-capacitance motor cables can also falsely trigger this fault. An unresolved short circuit poses a severe risk of damage to the drive's output stage.

• Short circuit between two or more motor phase windings (U, V, W).
• Short circuit between motor phase conductor and earth (ground).
• Short circuit within the motor cables (e.g., insulation breakdown due to mechanical damage or aging).
• Short circuit in the brake resistor circuit or its connecting cables (if applicable).
• Excessive capacitive charging current from very long or high-capacitance motor cables (especially unshielded).

Click steps to track your progress.

1. 1

   1. Disconnect the motor cables from the drive output (U, V, W) and measure the resistance between each phase cable conductor (U-V, V-W, W-U). Readings should be open or very high.

2. 2

   2. Perform an insulation resistance test (Megger) on each motor phase cable conductor to earth (ground). Values should be >1Mohm.

3. 3

   3. Disconnect the motor completely and measure the resistance between motor phases (U-V, V-W, W-U) and from each phase to the motor frame (earth). Readings should be balanced phases and high to earth.

4. 4

   4. If a brake resistor is used, disconnect it from the drive and measure its resistance value and continuity of its connection cables to the drive terminals (BR+, BR-).