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ground-fault neutralizer

ground-fault neutralizer

ground-fault neutralizer

(OP)
The study of sizing  neutral grounding of two generators in parallel 84MVA-13, 8kV has two solutions;
1 - by grounding resistor results in a current of 40A even with 1 generator grounded and the other ungrounded.
2 – with ground-fault neutralizer results in a current of 10A. This is the best solution.
 However we do not have any experience with this method of grounding.
 I wonder if there is a consultant specializing in this forum by resonant grounded to do contact?
 

RE: ground-fault neutralizer

Quote:

This is the best solution

Most grounding experts, at least in the US, would take strong exception to that claim.  Ground fault neutralizers have not been used much in the US for the past 50 years, at least.  

Without knowing more about the system, it is not possible to address your other claim that there only two solutions.  

For generators this size, by far the most common approach is individual high-resistance grounding of each generator.  This should limit ground fault current to less than 5 amps.  

I refer you to "Industrial Power System Grounding Design Handbook" by Dunki-Jacobs, et al, for a thorough explanation of the available options and their advantages and disadvantages.  IEEE also has recommendations for generator grounding (and it doesn't involve GF neutralizers).

 

David Castor
www.cvoes.com

RE: ground-fault neutralizer

(OP)
dpc,
I have been posted resonant grounded thread238-252879: resonant grounded with
this problem.
It was made studies of better alternative.
Now is time to decide.
I do not agree with your viewpoint of ground-fault neutralizer obsolecence.
 

RE: ground-fault neutralizer

I agree with dpc that NGR are the most common at 13.8 kV.

Quote:

by grounding resistor results in a current of 40A even with 1 generator grounded and the other ungrounded.

How is this a problem? You can always select a resistor value to limit the current to whatever you want. Also that is the benefit of a NGR that regardless of how many gens you have on line, you will always know the maximum ground fault current.

Although I have done mostly individual NGRs with each generator, there total ground fault current will add up but you still know the maximum value for each generator.

I am not much familiar with resonant grounding, but I have not heard of it at 13.8kV. I am equally curious to hear from those experienced in utility grade systems.

Rafiq Bulsara
http://www.srengineersct.com

RE: ground-fault neutralizer

It sound like you've already decided, so good luck.  The text I referenced does contain basic guidelines for sizing GF neutralizers.

 

David Castor
www.cvoes.com

RE: ground-fault neutralizer

(OP)
rbulsara,
No, you can´t. As higher is resistance more is overvoltage at good-phases to ground.There are limitation of overvoltage.
  

RE: ground-fault neutralizer

(OP)
dpc,
IEEE also has recommendations for generator grounding that involve GF neutralizers: C62.92-1989
We did not decide yet. We hope to decide only after found out somebody really has experience with ground-fault neutralizer.
 

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