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What is the purpose of Prospective Earth Fault Current measurement in a 3 phase DB

Apostolos

Good afternoon

On a 3 phase DB what is the purpose of measuring the PEFC?

I know we measure the prospective short circuit current between L1,L2,L3 and N and then double the highest reading. 

This is the Prospective Fault Current which is being recorded.

Why should we waste time with prospective earth fault current?

Are there cases where PEFC is higher than PSSC?

Thanks

Parents

  •  

    My take on it all is we have got to stop thinking in terms of the simple line diagrams we have been shown for Ze, PSCC and Zs with a single transformer and its earth with simple circuits from it in the DNO and consumers installations, because the grid is getting so complex with many connections to generators and lots of interconnections of earthing.

    Though having said that we have lost many interconnections of earthing through gas and water pipes over the last twenty years.

    Don't forget the original questions:

    Why should we waste time with prospective earth fault current?

    Are there cases where PEFC is higher than PSSC?

Reply

  •  

    My take on it all is we have got to stop thinking in terms of the simple line diagrams we have been shown for Ze, PSCC and Zs with a single transformer and its earth with simple circuits from it in the DNO and consumers installations, because the grid is getting so complex with many connections to generators and lots of interconnections of earthing.

    Though having said that we have lost many interconnections of earthing through gas and water pipes over the last twenty years.

    Don't forget the original questions:

    Why should we waste time with prospective earth fault current?

    Are there cases where PEFC is higher than PSSC?

Children
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