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Associate

Join Date: Jun 2013
Posts: 39

NER Body Termination And Cable Sizing

04/14/2014 2:36 AM

1)Do i need to terminate NER Frame earth? if yes, where is the location of termination point? is it at main substation earthing bar or grounding terminal of NER.

2) Neutral Grounding Generator cable is sizing based on full fault current rating without NER consideration or with NER con

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Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#1

Re: NER Body Termination And Cable Sizing

04/14/2014 8:44 AM

A1) What do the drawings say?

A2) What do the drawings say?

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Guru

Join Date: Oct 2012
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#2

Re: NER Body Termination And Cable Sizing

04/14/2014 4:05 PM

Although NER's will operate for most of their life at or near earth potential, they have to be treated as high voltage devices in terms of insulation rating, testing and maintenance.

In my opinion, there are a few fault cases in which a phase- to- phase voltage could be present at both ends of NER.

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Julius
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Anonymous Poster #1
#3

Re: NER Body Termination And Cable Sizing

04/15/2014 12:51 AM

What's a 'NER'?

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Guru

Join Date: Oct 2012
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#4
In reply to #3

Re: NER Body Termination And Cable Sizing

04/15/2014 1:56 AM
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Julius
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#6
In reply to #4

Re: NER Body Termination And Cable Sizing

04/15/2014 8:13 AM

Thanks, I hate acronyms, they screw up my knowledge base. Goggle, bing, yahoo found me nothing related.

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Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#7
In reply to #6

Re: NER Body Termination And Cable Sizing

04/15/2014 12:38 PM

www.acronymfinder.com for when the hate gets too great.

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#11
In reply to #7

Re: NER Body Termination And Cable Sizing

04/16/2014 8:33 AM

Thanks PWSlack, that's going to save me a lot of frustration, I searched NER there, found as used second from the end, NER {industrial elect}, why doesn't Google present this list instead of directing you to a page of holistic wear and then 350,000 more pages? It would be easier to pick as used and then narrow search....perhaps this should be suggested to them.

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#5

Re: NER Body Termination And Cable Sizing

04/15/2014 2:40 AM

Would suggest following:

1. Connect grounding point of neutral earthing resistance to its dedicated earth.

2. Connect metal frame of Enclosure to Station Earth.

3. Interconnect Dedicated earth of NER and Station Earth.

Reasons being:

1. NER needs testing at planned intervals and whenever it has carried earth fault current and its High Temperature Warning has sounded. Hence the earthing connection shall be such that we can disconnect NER from earth keeping its frame work still grounded for safety during HT testing.

2. It is likely that during earth fault potential of NER earth will rise and hence if the Station Earth and NER Earth are not inter-connected any person in contact with Station Earth can be subjected to potential of NER earth which in close vicinity of other equipment. If all earthing pits are bonded together, then practically equipment body and NER earth at same potential at all times.

Regarding sizing of cable of earth follow local codes which mostly specify size of earth conductor to maximum fault current and duration it has to carry subject to size not being less than minimum cross-section from Mechanical Point - hence though size of conductor may work out to small for the current it has to carry but applicable code of your area may specify minimum desirable size of earth conductor.

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Associate

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#8
In reply to #5

Re: NER Body Termination And Cable Sizing

04/15/2014 8:33 PM

If NER is rated for 400A, which sizing method should I choose?, based on 400A or based on fault level without NER?,

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Power-User

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#9
In reply to #8

Re: NER Body Termination And Cable Sizing

04/16/2014 1:07 AM

Pl size earthing conductor to carry 400 A maximum earth fault current through NER.

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Associate

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#10
In reply to #9

Re: NER Body Termination And Cable Sizing

04/16/2014 2:52 AM

I guess same goes to the body, If NER is limited to 400A, the max fault current would be 400A, so 70mm for switchgear body, NER body should be no problem isn't it.

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