[Question] PSCC Calculation

[CeeJay]

Hi guys the name is Clint, I'm very new here but after reading through the majority of the posts here I'm confident that this is the place to ask.

I'm writing installation rules paper 2 tomorrow, during my studying I've come across 2 variables in the PSCC Calculation in the memos. Now it's not that I don't understand the calculation. I'm just not sure which of the memos are correct.

When calculating a Three phase PSCC some memos make use of Ztotal=Zconductor+Ztra stormer. While others include Zecc in the Zt.

There's a common question that shows its head quite often especially the 3 phase one. I don't want to be studying the wrong thing it's 10marks down the drain almost.

Hoping somebody can clarify this for me before I write my exam

[CeeJay]

It's all good, a DC PSCC Calculation came in.

[Dave A]

I only came across this thread yesterday after lunch, and assumed making a post then would be too late to help.

[CeeJay]

Well aslong as somebody replied, I'm still not 100% certain on the correct answer.

In my head prospective SHORT CIRCUIT current is exactly that, a short circuit. Between 2 conductors. In my head I can't think of any reason for the Ecc's resistance to be added.

[CeeJay]

http://www.theforumsa.co.za/forums/showthread.php/8977-November-2010-Paper-2-Exam-Question-1-and-Question-2-(ANSWERS)

Theres the question. Now if you include Recc then the final PSCC is 2.2KA, but with some of the memos I have with the exact same question Recc isn't used and a final PSCC of 3.2KA is achieved.

But anyway, next problem is doing my Unit Standards😀

Thank you again in advance for any response.