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sethuamanj
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Join Date: Mar 2013
Posts: 14

Why and When We Need NGR / NER?

07/24/2013 11:17 PM

hello engineers. i saw some dyn11 transformer star point go to soild grounding and some dyn11 transformer with same rating dont have soild grounding. the star point is connected to NGR/NER and then connected to grounding. why and when we have to connect NGR? i know we connect NGR to reduce earth fault current.. but i want much more clear answer.. plz help me...
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Tornado
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#1

Re: why and when we need NGR / NER?

07/25/2013 12:21 AM

Sounds like a Google project to me...but not for me.

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TonyS
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#2

Re: why and when we need NGR / NER?

07/25/2013 1:23 AM

Think voltage and fault current.

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vyral2311
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Join Date: Mar 2013
Posts: 31
#3

Re: why and when we need NGR / NER?

07/25/2013 3:04 AM

For grounded system cables required are unearthed type. May be this could be your answer.
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PWSlack
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#4

Re: why and when we need NGR / NER?

07/25/2013 3:07 AM

<...connect NGR to reduce earth fault current...>

Is that clear enough?

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oldtex
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Join Date: Jul 2013
Posts: 2
#5

Re: Why and When We Need NGR / NER?

07/25/2013 10:30 AM

NGR/NER is often used to:

- Limit fault current on phase to ground faults (eg. on large generators to comply with NEMA MG-1 bracing requirements)

- Reduce circulating currents in neutrals where multiple machines are neutral grounded

- Suppress 3rd harmonic content where multiple machines or different characteristics (eg. generators of different pitch) are parallelled.
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msamad
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Join Date: Feb 2009
Location: Houston, USA
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#6

Re: Why and When We Need NGR / NER?

07/25/2013 4:44 PM

This link might be helpful: http://cr4.globalspec.com/comment/589279

- MS

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Simon Wan
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#7

Re: Why and When We Need NGR / NER?

07/28/2013 3:49 AM

What is the capacity of your dyn11 transformer?.

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