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Wye-Delta starter contributing to Short Circuit Level?

Wye-Delta starter contributing to Short Circuit Level?

Wye-Delta starter contributing to Short Circuit Level?

(OP)
We are doing short circuit calculations according to IEC 363 on a network where a motor is driven by a wye-delta starter.

In IEC 363 you can select the motor reactances to be calculated according to its relative starting current. However, the wye-delta starter of course reduces this starting current. So what relative starting current should I base my calculations on? The new wye-delta current or the original starting current of the motor (7xIn)?

RE: Wye-Delta starter contributing to Short Circuit Level?

Motor starting method has nothing to do woth SCC contribution. For estimating reactance, use the starting current is based on the full voltage starting.  

RE: Wye-Delta starter contributing to Short Circuit Level?

(OP)
Thanx...

What about cable lenght?

One-line diagram shows 50 metres before wye delta starter and 5 meters after... I assume that 55 metres is the correct lenght to use in my calculations??

RE: Wye-Delta starter contributing to Short Circuit Level?

All cable lengths should be included, however amount of SCC depends where the fault is. Hopefully you are using a software for SCC calcs. If not, it is hard to answer you question from here.

 

RE: Wye-Delta starter contributing to Short Circuit Level?

(OP)
Thank you. Yes, We use EDSA.... Great software btw...

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