choosing protection CT 1

[Pafi]

Hello!
I wonder if someone can help me with tips/ document about choosing a suitable current transformer for a protection application - short-circuit close to generator - where the load current is 1000A, Ik'' = 30kA and Ipeak = 80kA. I need to choose according to IEC.
Thanks!
Pafi

 

[alehman]

This is an involved question. The primary criteria is to select CT's that do not saturate under fault conditions. If they are being used for current differential relaying, it is important for the CT's to have similar performance.

Have a look at some of the references under Power System Protection in faq238-1287.

Alan
----
"It’s always fun to do the impossible." - Walt Disney

 

[RRaghunath]

Generally the relay manufacturers include CT sizing formula in the relay literaure. May be that should be helpful to start.

 

[slavag]

Hi Pafi.
Before few days we had thread on the topic.
Please see attached.
thread238-241062
You must choice CT also according to the relay's mnf. recommendation, for example, for the 87G, 87T protection ( as wrote Alan and Raghun).
Best Regards.
Slava

 

[slavag]

In additional.
I would recommend ABB's document too:

http://library.abb.com/global/scot/...E 9543 40-00en IT Application Guide Ed2.1.pdf

 

[Pafi]

Very usefull tips!
thanks, I found what I was looking for.
pafi