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#1

# Minimum Short circuit Ik min in a 155kV network

Dear all,

Can the minimum short circuit current of a 155kV network be smaller than the nominal current of the same network?

Thanks.
01-14-2014 05:46 AM
Top #2
Angel,

You are right to question whoever gave you this information since under most conditions this very unlikely. However if you are in the middle of a long transmission line with multiple voltage transformations and very distant from any generation, then the impedance will be quite high and limit the available SCC (Short Circuit Current). The voltage regulation under such a scenario will be quite poor as well.

Alan
01-14-2014 08:02 AM
Top #3
Agree. very very unlikely. for edification. i am curious to know more.

Regards
01-14-2014 11:00 AM
Top #4
Find out what is the maximum rating of power transformer used in 155kV network
01-14-2014 01:01 PM
Top #5
Dear all,

Thanks for your answers. The case that we are looking at, is a station power converter HVDC of 900MVA. For this station the minimum short circuit current for a single phase to ground fault, has been regarded as its nominal current. To put it in numbers, the nominal current at this power and in a 155kV network is 3,35kA. This 3,35kA value has been used as the minimum short circuit current for a single phase to ground fault. Can this be done? If yes, why?
01-14-2014 03:59 PM
Top #6
Yes that's the way,

The magnitude of am AC Isc is dependent on the Source namely the Transformer which produces it; (Inductive).

The Isc of a DC system is (Resistive). The Isc produced is directly proportional to the load or loads which produces it and remains constant.

Regards
01-14-2014 06:33 PM
Top #7
Ok. Thank you very much.

Angel