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Anonymous Poster

Neutral Grounding Resistor Questions

11/29/2010 2:11 AM

Good morning Sir,

I have been studying for Neutral Grounding Resistor ( NGR) and Peterson Coil ( PC )

So I want to ask a question to you.

In a grounded balanced system we use NGR or PC to limit the ground current ( according to this Formula )

IG=VLL/ (1,732 x RG )

So we can limit the charging current

IG>=3.IC0

If this theories are right:

Is our aim limit the charging currents of systems?

How can we limit the short circuit current especially for single phase to current?

What is relation between vaule of NGR or PC with short circuit current Ic

Best Regards,

Musa UÇAN

Electrical Engineer

İstanbul Leather Zone
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Join Date: Mar 2010
Posts: 33
Good Answers: 2
#1

Re: Neutral Grounding Resistor Questions

11/29/2010 11:44 AM

the aim is not to limit the charging currents but to limit the amount of single to ground fault current to a reasonable level depending on if it is a high impedance or a low impedance grounded system 5A-400A

The charging current is a value you add to your target fault current amount. for example if you have 6A of charging current (which depends on alot of factors) then you goal is limiting the fault current to 5A would entail you dealing with that charging current, prior to sizing.

Draw a diagram of a resistor between the three phases on the neutral prior to the ground connection - look at how the resistor will limit the fault current between phase A and ground. the current must flow through the resistor - which will limit the amount of current - V=IR

what is a PC?

Where is the Leather Zone?

Resistor or Reactor?

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Anonymous Poster
#2
In reply to #1

Re: Neutral Grounding Resistor Questions

11/30/2010 7:38 AM

Dear Sir,

Thanks for your answer.

PC= Peterson Coil

And I am working at İstanbul Leather Industrial Zone/TURKEY

Best Regards,

Musa UÇAN
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