Hi guys, wondering if anyone has come across a situation where a differential relay is connected across the incoming DC supply to a crane which is then controlling a contactor pulling in whats labelled as "BALLAST" resistors? they dont appear on any drawings available for the crane and AllenWest dont have any info on the installation itself so cant help. The fuses have been pulled so it is not in circuit.
The reason I ask is that we have just fitted a DC to AC inverter but this blew up due to regen from the system of up to 1100V. Is this device related?
Photo of the offending item is attached.