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Ht Softstarter

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#1 anu_rags


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Posted 06 July 2007 - 04:35 AM

Dear All,

Is it possible to install 690V softstarter on a 3.3kv 400kw motor for wood chipper application. For VFD, we used to install a step down transformer at the input of VFD, then at the output there was a sine wave filter and a step up tranformer afterwards. Is it possible to do the same way for a softstarter? Has anyone of you done this before?


#2 marke


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Posted 06 July 2007 - 05:40 AM

Hello Anurag

Yes, you can use a step down transformer and a step up transformer. You do not need the sinewave filter, but why not just use a standard MV soft starter. I am sure it would be cheaper!!

Best regards,

#3 jraef


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Posted 06 July 2007 - 06:28 PM

It's done all the time, but just be aware that the impedence of the load-side transformer then reduces the motor torque-per-amp from the soft starter, so your effective starting torque is further reduced, or really your line current draw is further increased without any usefull work being performed. Both transformer losses are also in the motor circuit permanently as well, reducing your overall efficiency during operation. If you have a lot of run time, you may want to consider that continuous energy cost in your comparison to considering using a medium voltage soft starter.
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