Allen-Bradley · PowerFlex 750
This fault is asserted when the DC bus voltage drops to 80% of its rated value on port 2. This indicates a significant loss of DC bus voltage which can lead to drive shutdown and loss of control.
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Measure the 3-phase AC input voltage at terminals R, S, T (Port 2) to confirm nominal values are present and stable.
Check the status of all upstream circuit breakers and fuses supplying power to the Port 2 input.
Monitor the actual motor current (e.g., Parameter P3-01 for Port 2) to verify it is within the drive's rated limits.
Inspect the DC link capacitors on Port 2 for physical signs of damage, such as bulging, leaking electrolyte, or discoloration.
Using a multimeter, measure the DC bus voltage across the P+ and N- terminals (Port 2) and compare it to the value displayed on the drive.