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Participant

Join Date: Jun 2008
Posts: 4

# Max Fault Current in a netwok

06/21/2008 2:45 AM

Hello folk,

I am not newbie but have forgotten about this sides. I have studies DEE.

I am working in a Power Station and going to find a Maximum fault current of a 11kv->Tx->415V line with CBs on both sides. The purpose of the assignment is to find capacity of CBs.

I presume that I would require calculating impedance of each path of network then sum up.

Does anybody have any online documents or such examples?

I would really appreciate your help.

Thanks,

KP

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Anonymous Poster
#1

### Re: Max Fault Current in a netwok

06/21/2008 11:40 PM

Ya really need to chase down a copy of the Westinghouse Transmission and Distribution Reference Book, now available from ABB. And READ IT!!

Active Contributor

Join Date: Feb 2008
Posts: 11
#2

### Re: Max Fault Current in a netwok

06/22/2008 10:47 AM

Is your "power station" generating at 415 volts or at 11,000 volts? Sounds like you are trying to determine the required "fault interrupting capability" of the breakers, not their "capacity". Just considering the available fault current for the line (and not any contribution from your genertor(s)) you'll need the source impedance of the line and the impedance and base MVA rating of the transformer. Gives us a little more information and maybe someone can help...

Participant

Join Date: Jun 2008
Posts: 4
#4
In reply to #2

### Re: Max Fault Current in a netwok

06/22/2008 10:45 PM

Sorry,

I have studied DEE and Robotics Eng. So I am creating confusion here.

The station generates 1GW @ 20KV however I have to determine fault interrupting capabilities and also impedance and KA ratings of switchgrears in various 11KV-415Kv lines around the station.

I know its big job and certainly not a cake for Robotics Eng but I have been assigned the job and I got to do it.

I will be up with some figures asap.

Cheers,

Anonymous Poster
#3

### Re: Max Fault Current in a netwok

06/22/2008 11:47 AM

divide the ratted current of the power transformer by its percentage impedance and multiply by 100 will gives the maximum fault current. if the line impedance are accounted then it will be some what lower.

ponnusamy thanjavur India

Participant

Join Date: Jun 2008
Posts: 4
#5
In reply to #3

### Re: Max Fault Current in a netwok

06/22/2008 10:48 PM

Hi Pon,

Do you have some sample calculations or examples with line dia and stuffs ?

cheers,

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