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fikri.aziz
Participant

Join Date: Dec 2012
Posts: 1

Neutral Earth Resistor(NER) Indication at Switcgear

12/25/2012 11:12 PM

I have a 6.35kV NER for 33kV/11kV 10MVA Transformer. My client asking to put the NER indication and interlocking at switchgear panel . I am considering semaphore indication for monitoring but at the interlocking part I am still in not sure.

Please advise what aspect I need to look on and advise also on the connection since I am still new in designing.

Thanks in advance.
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arifkunnath
Commentator

Join Date: Oct 2011
Posts: 95
#1

Re: Neutral Earth Resistor(NER) Indication at Switcgear

12/26/2012 2:59 AM

Please see this site

dimako.com/more-products/neutral-earthing-protection-system/
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debata07
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Join Date: Nov 2011
Posts: 131
Good Answers: 5
#2

Re: Neutral Earth Resistor(NER) Indication at Switcgear

12/26/2012 11:03 PM

You may provide a neutral CT for monitoring current in the NER circuit as well as earth fault protection. The CT will have two cores. One core can be connected to an ammeter or a current transducer for monitoring earth fault current on continuous basis. The second core can be connected to a earth fault relay for tripping the circuit breaker in the switchgear panel in the event of earth fault current exceeding the set point of the relay.
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moody
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Join Date: Sep 2009
Location: EGYPT
Posts: 4
#3

Re: Neutral Earth Resistor(NER) Indication at Switcgear

12/27/2012 5:31 AM

hii fikri, if u are from egypt mail me at.

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eugene344
Active Contributor

Join Date: Jun 2011
Posts: 24
Good Answers: 4
#4

Re: Neutral Earth Resistor(NER) Indication at Switcgear

12/27/2012 9:01 PM

NER interlocking usually includes tripping of the transformer/s if the neutral is not earthed (neither the NER nor direct earth connection in service.)

If this interlocking is part of the specified system, include an audible alarm for the neutral not earhed, and consider a time delay long enough for an operator to correct (i.e. reconnect the neutral earth) before the transfomer trips.
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Previous in Forum: How to Determine the Number of Cores and Core Ratio of CT's to be Used?   Next in Forum: Capacitor Bank

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