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VSD DAMAGED - WHY?


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#1 Guest__*

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Posted 29 June 2004 - 07:40 AM

Hi there! I hope someone will be able to assist me. I work at a factory in South Africa. Recently, we installed a Danfoss VSD to drive an induction motor. About one month after installation, the VSD stopped working. We are now trying to establish the cause for this. During installation, brackets were welded onto the casing of the VSD to mount it against a wall. Some of our engineers now reckon that the VSD stopped working as a result of this welding. I question this however, especially since the VSD worked fine for just over a month. On inspection, I found that the cooling air inlet at the bottom of the VSD was completely blocked. I therefore suspect that that the VSD consistently ran at an above-average temperature during the month, during which the components were gradually damaged until the finally failed after a month. Is this possible? Do you have any other ideas? And most importantly, is it possible that the VSD would be damaged by the fact that we welded the brackets onto its case? Thank you for your assistance.;p;;p;

#2 marke

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Posted 04 July 2004 - 07:13 PM

Hello

The damage to the drive can be caused by welding if the drive was connectd to other equipment, when the arc welding was done.
If the drive was not connected to anything else, I would not expect to see damage occur.
The arc welding is based on the establishment of an arc and this creates high curent anc resultant voltage transients. These transients are capacitively coupled into parts of the circuit by external connections and can cause damage to components. This damage my result in the weakening of components that may fail after a period of rime. - a little like electrostatic damage.
If you use an arc welder around electronic equipment, remove all connections from that equipment before commencing the welding.
Best regards,

#3 Guest__*

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Posted 26 August 2004 - 07:38 AM

QUOTE
Originally posted by Anonymous
Hi there! I hope someone will be able to assist me. I work at a factory in South Africa. Recently, we installed a Danfoss VSD to drive an induction motor. About one month after installation, the VSD stopped working. We are now trying to establish the cause for this. During installation, brackets were welded onto the casing of the VSD to mount it against a wall. Some of our engineers now reckon that the VSD stopped working as a result of this welding. I question this however, especially since the VSD worked fine for just over a month. On inspection, I found that the cooling air inlet at the bottom of the VSD was completely blocked. I therefore suspect that that the VSD consistently ran at an above-average temperature during the month, during which the components were gradually damaged until the finally failed after a month. Is this possible? Do you have any other ideas? And most importantly, is it possible that the VSD would be damaged by the fact that we welded the brackets onto its case? Thank you for your assistance.;p;;p;


#4 Guest__*

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Posted 26 August 2004 - 07:42 AM

I have many Danfoss VSD in use for a long time and seen no special problem encourtered. But you should remember that heat will generate during on load and the IP is very important, if low IP model, VSD must installed in air-conditioned plant room.

#5 Carl

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Posted 30 May 2005 - 07:44 PM

I would agree with Mark as I've experienced the exact same problem in the past regarding welding near ac inverters.

But.. the failing of the cooling fan could put he power devices out of its safe operating zone depending on how hard the inverter is working. If I recall correctly the danfoss drive has a temperture sensor to cut off the inverter.




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