Generator Neutral Grounding Resistor

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deedo1124

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I was reviewing a landfill site where a NGR is used to limit fault current at the generator. The generator has a dedicated Y-Y GSU. Since the generator neutral is bonded to ground through the resistor shouldn't the bond between the GSU XO terminal and ground be removed? I noticed that it was installed and it seems that this will negate the protection provided by the NRG? The generator is 1500KW, 480V and step up is to 34.5KV. Start up is next week and want to insure this is correct before proceeding.

Thanks
 
deedo,

The EBJ should run from the first system disconnecting means to the grounded

side of the grounding impedance. 250.36(E) NEC 2005 , that's only for 480-1000 v.

Hopefully the H.V. guys will chime in here to help you out.
 
Off the top of my head I would have to wonder first "Y-Y"?

Normally, the GSU would be a Delta (LV), with a grounded wye HV side.

Something to consider, if the generator has a low side gen breaker for synchronizing across, then you will have an ungrounded transformer being back-fed from 34.5kV system during start-up. Not that you couldn't do it, just be aware.
 
We have 22 generators in sync (1275 kw 60 hz).

We used YNd11 GSU for all of them.

Secondary Neutral is solidly grounded.

cheers
 
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