Treatments for Overcurrent Faults:
Make sure you inspect the appliance/machine you are working with to see if it’s stuck or bound in some way, preventing the motor from turning.
Ensure the motor is not shorted.
Try using a megger to check if the ground is not shorted to any legs of the motor.
Verify that the power module of the VFD is not damaged or shorted.
There are many reasons for AC inverter over-current fault. The inverter output was short-circuited, or the motor shaft is locked or has a heavy load. These conditions cause excessive current for the inverter, so the inverter output is turned OFF.
It could also be that the dual-voltage motor is wired incorrectly.
Pure Sine Wave Inverter with Inductive load:
If you use this type of devices, please use the pure sine wave inverter that is 4 times higher than the rated power, because the peak power of the pure sine wave inverter is 2 times the rated power (inrush), which has actually reached the inductive load 8 times the peak power at startup.
Running defective equipment causing the error 51 will eventually destroy the internal capacitors of the inverter rendering the inverter useless, this is why equipment especially induction loads need to be PAT Tested. Anything where the motor is in contact with humidity, moisture or dust will cause issues.
This is a safety protocol on the inverter and is there for your own safety, the system is better than an RCD, RCBO or MCB.
The vast majority or errors are caused by a defective appliance not the inverter.