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Cable short circuit dynamic I peak value

Cable short circuit dynamic I peak value

Cable short circuit dynamic I peak value

(OP)
Cable short circuit dynamic I peak value has been requested by switchboard supplier. This cable is used to connect between two DC switchboards(VFD) to drive VFD motors. It seems that this is not thermal data. Can it be informed by cable manufacturer ?
Can anybody explain what it is and what it is used for, short circuit calculation or any other ?

RE: Cable short circuit dynamic I peak value

I think the short dynamic I peak value is the peak value of the short circuit current and does not depend only upon cable X and R but upon entire circuit - Sum(X) and Sum(R)- from the upstream transformer and up to driven motors. This include the symmetrical I"sc and maximum DC current. The "thermal data" is the average current resulted by squared integration of the current curve from time=0 to clear fault time divided by clear fault time. Usually maximum Ipeak=1.8*sqrt(2)*Isc. If the cable connect VFD to motor you may ask from VFD supplier the short circuit current [I"sc –rms ] and neglecting the cable impedance to calculate: Ipeak=2*sqrt(2)*I"sc.Will be a little conservativ but fair.
See:
http://books.google.com/books?id=V1SXEnhCN88C&;pg=PA364&lpg=PA364&dq=short+circuit+dynamic+I+peak+value&source=web&ots=KMPclCbsni&sig=kr_eOBCb9ltupaL9LygOvwOy77s&hl=en&sa=X&oi=book_result&resnum=8&;ct=result

 

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