Hi,we have a CNC machine that uses 7 servo drives (3 phase drives, Yaskawa 200V). Recently, someone destroyed (shorted phases together) one of the motor wires, which caused the drive to explode. The drive and wire were replaced,but we noticed that the EMI filter had one phase burned out, so we replaced the EMI filter (a no-nema chines 3-phase filter) with a 3-123-506 mains filter, a 3-phase 64A 760V 900uOhm Schurter filter. After the replacement, when we powered up the CNC, one of the drives exploded. The safety capacitors (from phases to ground) and MOV had exploded. We checked all the phases and neutral ground wires and found one that seemed to be lost. After we powered again and a different drive was expeloded (MOVS that goes between phases),
So now I really don't know what to do. Can the problem be that the new EMI filter does not filter the noise as well as the old one, which causes big voltage spikes that destroy MOVS?
Thanks for the help!