A 75kW Allen-Bradley PowerFlex 755 Variable Frequency Drive was brought to our facility with a reported ground fault condition.

Upon receipt, comprehensive cold testing and power testing were carried out to diagnose the issue. The investigation revealed faults in both the power board and other components of the input section, which were identified as the root causes of the ground fault.

Our technical team proceeded with replacing the defective components. After reassembly, the drive was subjected to functional testing under load conditions by connecting its output to a suitable electric motor. The drive operated normally and met expected performance standards.

The project included:

• Cold testing of IGBTs and thyristors using a multimeter to confirm component integrity
• Continuity testing to ensure no short circuit between phases and earth
• Careful tagging and disconnection of all power board connections
• Replacement of compromised  components with OEM-certified  parts
• Load testing of the drive with a 45kW electric motor

The work was completed within schedule, and the drive was successfully restored to full operational condition and delivered to the customer.