VFD Failure

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Bob Clukey

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We had an incident here that we wanted some input on. We were installing a. 3 phase 575 to 480 vac transformer. When it was energized, we destroyed 8 575VAC 3 phase drives. It was discovered that it was a Y transformer and we have a delta ungrounded. Does anyone have an idea why our drives were damaged and as far as we know, no other equipment? I am told that there was an H/O connection and an X/O connection that were both grounded. Any input will be appreciated!
 
Bob Clukey said:
We had an incident here that we wanted some input on. We were installing a. 3 phase 575 to 480 vac transformer. When it was energized, we destroyed 8 575VAC 3 phase drives. It was discovered that it was a Y transformer and we have a delta ungrounded. Does anyone have an idea why our drives were damaged and as far as we know, no other equipment? I am told that there was an H/O connection and an X/O connection that were both grounded. Any input will be appreciated!
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Read the drive manual for the different connection requirements of drives to solidly grounded, resistance grounded and ungrounded systems. ABB - for example - requires the disconnection of some internal filters. It is somewhat unusual that it destroyed the drives, it should just have caused minor damage, malfunction.
 
Bob Clukey said:
We had an incident here that we wanted some input on. We were installing a. 3 phase 575 to 480 vac transformer. When it was energized, we destroyed 8 575VAC 3 phase drives. It was discovered that it was a Y transformer and we have a delta ungrounded. Does anyone have an idea why our drives were damaged and as far as we know, no other equipment? I am told that there was an H/O connection and an X/O connection that were both grounded. Any input will be appreciated!
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I don't see how the primary side misconnection could have damaged the drives. Some drives want a grounded system and have a jumper you can remove to deal with ungrounded power systems, but I don't think the jumper out will make it fail on a grounded power system.
 
petersonra said:
I don't see how the primary side misconnection could have damaged the drives. Some drives want a grounded system and have a jumper you can remove to deal with ungrounded power systems, but I don't think the jumper out will make it fail on a grounded power system.
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ABB Manual:"WARNING! To avoid danger, or damage to the drive, on IT systems and cornergrounded TN systems, see section Disconnecting the internal EMC filter on page 23.""Disconnecting the internal EMC filterOn certain types of systems, you must disconnect the internal EMC filter, otherwisethe system will be connected to ground potential through the EMC filter capacitors,which might cause danger, or damage the drive.Note: When the internal EMC filter is disconnected, the drive is not EMC compatible.The following table shows the installation rules for the EMC filter screws in order toconnect or disconnect the filter, depending on the system type and the frame size.For more information on the different system types, see IT systems on page 280 andCorner grounded TN systems on page 279.The locations of screws EM1 and EM3 are shown in the diagram on page 21. Thelocations of screws F1 and F2 are shown in the diagram on page 22."
 
weressl said:
ABB Manual:"WARNING! To avoid danger, or damage to the drive, on IT systems and cornergrounded TN systems, see section Disconnecting the internal EMC filter on page 23.""Disconnecting the internal EMC filterOn certain types of systems, you must disconnect the internal EMC filter, otherwisethe system will be connected to ground potential through the EMC filter capacitors,which might cause danger, or damage the drive.Note: When the internal EMC filter is disconnected, the drive is not EMC compatible.The following table shows the installation rules for the EMC filter screws in order toconnect or disconnect the filter, depending on the system type and the frame size.For more information on the different system types, see IT systems on page 280 andCorner grounded TN systems on page 279.The locations of screws EM1 and EM3 are shown in the diagram on page 21. Thelocations of screws F1 and F2 are shown in the diagram on page 22."
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Unless the OP left out some very important information I do not see that it is a corner grounded system. If it was an It system (I think that is the IEC designation for what we would call ungrounded delta, the jumper would be removed. However since the OP indicated the HO was bonded, essentially they created a wye system on the primary side. How is that going to hurt the drive regardless of how the jumpers are set.

in any case if it was corner grounded and they bonded H0 on the primary side they would have done more than damaged a few drives.
 
petersonra said:
Unless the OP left out some very important information I do not see that it is a corner grounded system. If it was an It system (I think that is the IEC designation for what we would call ungrounded delta, the jumper would be removed. However since the OP indicated the HO was bonded, essentially they created a wye system on the primary side. How is that going to hurt the drive regardless of how the jumpers are set.

in any case if it was corner grounded and they bonded H0 on the primary side they would have done more than damaged a few drives.
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OP: "It was discovered that it was a Y transformer originally and now we have a delta ungrounded."

My emphasis added on how I understood the original post. Please refer to the manual for the variety of grounded, ungrounded or high resistance grounded systems to make the appropriate changes to the drive so the filter connections left in place inappropriately will not cause damage to the drive.
 
ptonsparky said:
I have yet to understand it.

Was the OP putting the 575v drives on a 480v transformer, or was the installation of an improperly selected/installed 575 to 480v transformer the problem. Or both.

IDK, are 575v drives rated for use on 480v?
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Me either, OP did not say exactly what he is doing. I took OP to mean he installed a transformer with 575 on primary and 480 secondary, and there was a problem afterward with existing drives on the 575 system, but that doesn't seem like it should introduce much of a problem normally. Op did not say what is being supplied by this added transformer.
 
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