Indramat servo drives

Hello All,
We just smoked 7 indramat drives. They power up on 24vdc and once you clear the e-stop circuit, that is when 3 phase 480 is applied to the drives through a contactor (that is now welded). I called tech support and they instructed me to do a bridge/ diode check of the drives. They all check shorted.
We have decided to disconnect the bus links that connect all the drives together when we get repaired drives back from the shop. We don't know what caused this to happen. I have been doing insulation tests on the motors and wirirng but can't find any problems. Any suggestions greatly appriciated.

Were line and load conductors switched, by chance? I've seen drives wired backwards, and they don't like it.

-rpoet

This machine has been in operation for 5+ years. There is a 3 phase line filter ahead of the drives but I'm not sure how to check it.

Can you give some more detail on how this actually happened? Had there been any work or repairs on the machine prior to this incident? WHat type of drives are they (Ecodrives, Indra-drives, etc. I do not see how every drive could get smoked at the same time. If the filter is shorted it should take out your fuses and maybe the contactor but anything downstream (the drives) should be safe as the path of least resistance is thru the shorted filter. In my opinion for this to happen there must be something in common with all 7 drives. I assume each drive has its own motor and cables so that is out of the question. I would almost have to say that the only possible culprit would have to be your input power, could you have had a lightning strike? Could your 480 supply have gone extremely high or low? Do the drives share a DC power buss? Maybe the power supply is at fault. What I am getting at is that it must be something common to all the drives which has to narrow it down to 1 or 2 items.

These are Eco drives. The OEM thinks that having all the buses tied together is the problem.

It sounds to me like the drives weren't properly protected. A short on the input side of one shouldn't take out all of them.

It sounds like the common bus went high and caused this. Are these PM servos or induction motors? When the bus contact was pulled in is there any chance the machine was spinning and when the bus contact was pulled in it dumped the power back.

Any auxiliary modules fitted to the common DC bus?
, BZM (bleeder) or CZM (capacitance).

If I recall correctly, our Indramats are powered from a common PSU 3ph.415v ac - 570v dc bus. So if you supply 480v to each of the 7 drives then whats the purpose of the bus links?

.

any chance you regenerated energy from the motors through to the power supply?
this is bad, if it happens, and if you have a non-regen power supply

I have 9 Eco drives connected on the line side. I would think they would be able to protect them selfs. Better reason for me to go to applied motion.
I have to add that the have protection at each drive.