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Impedance of Transfomers in Ohms

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Mbrooke

Electrical
Joined
Nov 12, 2012
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2,546
Location
US
Does anyone know how I can turn transformers into a simple ohm value as done with wires? I'm looking to make a series of tables electricians can use onsite.

One can, for example: for a single L-G fault choose 0.016 ohms for the POCO transformer, 0.002 ohms for the service, 0.035 ohms for the feeder (phase + EGC) and 0.25 ohms for the branch circuit (phase + EGC) to its furthest point.

Simple ohms law would take you to the required destination.

This can be used to find max fault current and to determine breaker disconnection times.
 
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