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Rental Generator Grounding Potential Rise

Rental Generator Grounding Potential Rise

Rental Generator Grounding Potential Rise

(OP)
We are renting a 13.8kV/4.16kV Genset. It is not indicated in the original contract which party is responsible to limit the grounding potential rises of all parts of the station ground grid to 5000V and  touch and step voltage at the edge, within, and around the generator grounding electrode shall not exceed the tolerable values specified in CEC Table 52.

ETAP simulation shows the GPR exceeds the limit. Can we pass the resonsiblity to Rental genset supplier. Or we can install  a rsistivity gravel around the rental genset to limit GPR, the step and touch potentials.  

Thanks in advance.
 

RE: Rental Generator Grounding Potential Rise

Whose personnel will be connecting the set?

RE: Rental Generator Grounding Potential Rise

(OP)
We are providing cables and grounding to the tie-in points.Rental genset supplier is responsible for the the start-up, commisiosning and running maintenance.

RE: Rental Generator Grounding Potential Rise

Are you serious?  How can you possibly expect the rental company to assume responsibility for your grounding system and soil conditions?  When you rent a car do you expect Hertz to make sure the roads are not icy?   

"Theory is when you know all and nothing works. Practice is when all works and nobody knows why. In this case we have put together theory and practice: nothing works... and nobody knows why! (Albert Einstein)

RE: Rental Generator Grounding Potential Rise

If the analysis was done properly, it is unlikely that fault contributions from the generator caused the high GPR and touch potentials because it is a local source.  Consider also that the line-to-ground generator voltage is less than the allowable GPR.  Setting responsibility for GPR from utility system fault sources on the generator supplier would seem a stretch unless it was clearly spelled out in their contract.
 

RE: Rental Generator Grounding Potential Rise

HamidEle,

While agreeing with jghrist,I too should ask,

1)Generator is a local source.So how does it cause GPR and touch potentials?

2)Generator line to ground voltage is very much less than the allowable GPR in CEC.Then why are you worried about GPR and touch potentilas?

 

RE: Rental Generator Grounding Potential Rise

Hi Hamid;
I'm a little confused by 13.8kV/4.16kV Genset.
Should this be 13.8kV/7.97kV or 13.8kV/4.16KVA?  

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Rental Generator Grounding Potential Rise

(OP)
The generator is feeding the 4160V system. The generator star point is 13.8KV, secondary is 4160V.This generator star pint is grounded through a 300A resistor. So the ground fault is limited to 300A, 0.5s. The calcualted touch and step potential is below the limits. GPR also meets the requirements.

RE: Rental Generator Grounding Potential Rise

30 Jul 09 2:28

Quote:

ETAP simulation shows the GPR exceeds the limit.
31 Jul 09 1:47

Quote:

The calcualted touch and step potential is below the limits. GPR also meets the requirements.
Which is it?

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