UnderVoltage

What does F4 mean?

The drive has detected that the DC bus voltage has dropped below its predefined minimum operating threshold. This condition typically occurs due to low incoming AC line voltage, a momentary power interruption, or excessive voltage sag from the utility supply. Sustained undervoltage can prevent the drive from operating correctly, cause nuisance trips, or indicate a problem with the main power supply, potentially halting equipment operation.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Verify that main disconnects and circuit breakers supplying the drive are fully engaged and properly sized.