Battery cabinet DC bus overvoltage

What is a DC BUS overvoltage fault?

A DC bus overvoltage fault simply means that the DC bus voltage exceeded the threshold for which the drive is rated. It is an instantaneous fault, meaning as soon as the voltage crosses this level, the control system detects this and trips the drive into a fault condition, disabling the drive’s output. This is to protect the VFD from damage.

Why does a variable frequency drive have a DC BUS overvoltage fault?

Variable Frequency Drives (VFDs) often experience DC bus overvoltage faults when decelerating motors with large inertial loads. This typically happens because the motor, suddenly forced to slow down, behaves as a generator, sending energy back into the drive. The drive’s DC bus voltage then rises above safe limits, triggering an overvoltage trip.

What happens if DC BUS overvoltage is greater than 460V?

If the average DC bus voltage is greater than 460V, the DC bus overvoltage fault will be generated. Auto Action: DC Bus Over-voltage Fault will immediately turn-off the Inverter in hardware. The PFC will be turned off upon detection of this fault. Possibility-1 (Inverter relay is closed)

Can a 230 VAC power source cause a DC BUS overvoltage fault?

Note that a 230 VAC high-Delta power source can be the sole culprit of a DC bus overvoltage fault if the error appears when the drive isn’t running. A high-Delta power source may need to be fed through a Delta/WYE isolation transformer upstream of the VFD if it is determined that this is the problem.