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shivvaram
Associate

Join Date: Jan 2009
Posts: 44

When to Go for Neutral Grounding Through Resistance

02/14/2013 8:00 AM

Helo everyone,

Can anyone kindly tell me on what decides the choice of going in for a) solidly earthed neutral and b) neutral grounded through NGR. My trfo capacity is 2.5 MVA, 33 / 0.433 kV

I understand the choice will be based on the allowable fault current to flow in the system. But I am not fully aware on this subject. Can anyone throw more light on this aspect.

May i also know the advantage and the draw backs of selecting between the aboce two options.

Thanks in advance.

Ramesh.A
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lyn
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Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: When to Go for Neutral Grounding Through Resistance

02/14/2013 8:09 AM

The engineer on the project will decide, based on his experience and the

IS CODES- Indian standards
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TonyS
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United Kingdom - Member - New Member

Join Date: Aug 2010
Location: Resting under the Major Oak
Posts: 4347
Good Answers: 181
#2

Re: When to Go for Neutral Grounding Through Resistance

02/14/2013 9:31 AM

If the star point of the .433 is used as neutral it can not be grounded through a NER. This is to prevent a voltage rise above ground potential under fault conditions.

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nobodysomebody47
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Join Date: Nov 2011
Posts: 171
Good Answers: 1
#3

Re: When to Go for Neutral Grounding Through Resistance

02/14/2013 10:38 AM

You may find some useful info here

Neutral Grounding
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PeterT
Guru

Join Date: May 2010
Location: Liverpool, NY
Posts: 961
Good Answers: 131
#4

Re: When to Go for Neutral Grounding Through Resistance

02/14/2013 1:36 PM

A historical treatment of how neutral grounding has been done (low and high resistance grounding vs. solid grounding), with explanation of why various alternatives were chosen is found in this good reference:

http://www.postglover.com/TechLibrary/History_Of_Neutral_Grounding.pdf

Explanation of how to choose is given in this technical paper:

http://www.postglover.com/TechLibrary/Grounding_Industrial_Power_Systems.pdf

Other resources are also available on Post Glover's web site Technical Library, among other places (do a Google search on resistance grounding).

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KITES
Active Contributor

Join Date: Jan 2013
Posts: 10
#5

Re: When to Go for Neutral Grounding Through Resistance

02/21/2013 12:27 PM

NGR is used to limit the eart fault current to a specific value. The earth fault current is limited by the value of NGR.

If you adopt the solidly grounded system(without NGR), the E/F current will be almost close to or same as 3phase S.C currents.
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