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Anonymous Poster #1

How to Reduce High Short Circuit Level on 11KV Network

05/04/2012 9:30 AM

We have main intake power source from the power authority via 5 paralell 30MVA, 132/11KV transformers. How can we limit the Short Circuit level which is 850MVA to 500MVA.on our main 11KV sectionalised switchboard. What type of limiter is the best and why?

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#1

Re: How to Reduce High Short Circuit Level on 11KV Network

05/04/2012 12:07 PM

Homework?

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Guru
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#2
In reply to #1

Re: How to Reduce High Short Circuit Level on 11KV Network

05/04/2012 2:51 PM

Let us hope so.

Why? Because... the idea that someone who is responsible for a system that can generate 850MVA of fault current, has to come to an Internet forum for advice on how to manage that system is truly scary.

Glad I do not work there.

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#3

Re: How to Reduce High Short Circuit Level on 11KV Network

05/04/2012 3:01 PM

1. Don't operate them all in parallel.

2. Add appropriately sized current-limiting reactors on the secondary (11kV) side of each transformer.

3. Increase the % impedance characteristic of the transformers to reduce the available fault current levels.

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#4

Re: How to Reduce High Short Circuit Level on 11KV Network

05/04/2012 4:22 PM
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#5

Re: How to Reduce High Short Circuit Level on 11KV Network

05/04/2012 5:18 PM

OK first hold this cable.

There are reasons that all electrical work should only be done by licensed, properly trained individuals.

Now hold this cable in your other hand.

If you are trying to refresh your memory about what you should already know, go back to your training classes and look up the correct material in your electrical code books. If you do not know which code standard applies in your area, you are not qualified to do this work.

Now I'll just throw this switch so you can see what a 480VAC arc flash feels like.

If you are student, you will kill somebody because you refused to do your own school work.

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#6
In reply to #5

Re: How to Reduce High Short Circuit Level on 11KV Network

05/05/2012 7:28 AM

Impresive and interesting discussion indeed..

What is the optimum Short Circuit Current on medium voltage (11KV) in indudustry?any specific value/standard?

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