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Join Date: Jun 2008
Location: Located in Qatar, working as an Project Coordinator
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### Source MVA

07/24/2012 5:26 AM

In general for fault calculation at 11kV panel within consumers premises where in we connect 11kV/433V transformer, we need source MVA? If Source MVA is not available then we consider node MVA (battery limit of MVAsc upto Primary substation). What value of this source MVA in general needs to be considered?

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Commentator

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#1

### Re: Source MVA

07/24/2012 8:21 AM

Take 500MVA for source short circuit capacity in short circuit calculation

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#2

### Re: Source MVA

07/25/2012 1:21 AM

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#3

### Re: Source MVA

07/25/2012 8:29 AM

That will depend upon the rated MVA & the % impedance of the upstream Transformer feeding your 11 kV panel.

For example:If the rating of the upstream transformer is 132 kV/11 kV,50 MVA with 12% impedance, the source MVA for fault condition will be =50 /0.12 =416.67 MVA neglecting the reduction due to impedance of the feeding line.

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#4

### Re: Source MVA

07/29/2012 8:43 AM

IS 2026 gives guideline values of Source Fault Level, if actual values are not know. But, this is pertaining to Indian Electricity Grid only. You have to contact the Qatar Electricity Authorities for the grid fault level at various voltage levels.

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#5

### Re: Source MVA

07/31/2012 9:12 AM

you can also use the impedance of the transformer that the 11kV panel is connected. Use (1/Zpu) which will give you the maximum fault current at infinite source impedance.

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electricalexpert65 (1); hkian (1); mohd.imran (1); Mushtaq Hussainh (1); spradhan (1)

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