Fuse Blow off -Drive Circuit

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RNLENI

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I have two 20 KW Motors in a ware house freezer environment (-22F) . Both motors are used for lifts and fed by separate circuit 480V AC. Both motors have separate Lenze i950 drives (22kw) with 50A Class J fuse upstream. Issue is that when the systems starts working for some time then Fuse blows.
Motors are changed, cables are changed and drives are changed. Also during fuse blow, Drives are also damaged (replaced many drives). Last week all the upstream breakers are tripped and customer feed is also tripped. No short circuit is noticed . Any clues of what is causing the fuse blow and all the breakers and disconnects till the customer feed getting tripped?
 
RNLENI said:
I have two 20 KW Motors in a ware house freezer environment (-22F) . Both motors are used for lifts and fed by separate circuit 480V AC. Both motors have separate Lenze i950 drives (22kw) with 50A Class J fuse upstream. Issue is that when the systems starts working for some time then Fuse blows.
Motors are changed, cables are changed and drives are changed. Also during fuse blow, Drives are also damaged (replaced many drives). Last week all the upstream breakers are tripped and customer feed is also tripped. No short circuit is noticed . Any clues of what is causing the fuse blow and all the breakers and disconnects till the customer feed getting tripped?
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I seem to recall that Delta power systems are what IEC refers to as IT. Are you by any chance on a delta power system?
 

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What part of the drives are damaged? If the rectifier/front-end is going then it's a good bet that the problem is on the line side. And maybe the failures aren't related to the drive operation at all.
Does there facility have switch power-factor correction caps? Switching transients can occasionally cause fun.
Have you put a recorder on the line side somewhere to look for voltage or current spikes? Heck, put a recorder on the service, could be something upstream at the PoCo.

(Just saw the IT post- would that account for blown fuses, too?)
 
RNLENI said:
I have two 20 KW Motors in a ware house freezer environment (-22F) . Both motors are used for lifts and fed by separate circuit 480V AC. Both motors have separate Lenze i950 drives (22kw) with 50A Class J fuse upstream. Issue is that when the systems starts working for some time then Fuse blows.
Motors are changed, cables are changed and drives are changed. Also during fuse blow, Drives are also damaged (replaced many drives). Last week all the upstream breakers are tripped and customer feed is also tripped. No short circuit is noticed . Any clues of what is causing the fuse blow and all the breakers and disconnects till the customer feed getting tripped?
Click to expand...
I think you need to find out what is taking out the drives, the fuse likely is just responding to the drive failing and not the other way around.

Transients on supply side as mentioned are a good place to start looking.

Do you have line reactors ahead of drive input? That possibly helps.

Are you operating on a delta secondary but the drive needs to be on a wye secondary with equal voltages to ground from all three input lines?
 
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