Wye-Delta starter contributing to Short Circuit Level? 1

[Beo81]

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)?

 

[rbulsara]

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

 

[Beo81]

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??

 

[rbulsara]

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.

 

[Beo81]

Thank you. Yes, We use EDSA.... Great software btw...