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22 kV zigzag transformer fault current

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Power0020

Electrical
Jun 11, 2014
303
Is there a common value used for line to ground fault current on 22 kV systems? is it something like 500 or 650 A? or few tens of amps?
 
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There's no typical value. It will depend on the Thevenin-equivalent positive, negative, and zero sequence impedances and positive sequence voltage at the fault location.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
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If you are using a neutral grounding resistor with your zig-zag transformer the resistor will limit the ground current based on the value of the resistance and the line to neutral voltage, or line to line voltage divided by root three.
The value is often set to be greater than the line charging current.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
I got a rough figure for a local experience with 100 ohms per phase, i.e. 127 A L-G fault, much higher than cable charging current.
 
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