Neutral Current

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lalit_nawada Commentator Join Date: Apr 2009 Location: CG Posts: 64	Neutral Current 05/15/2009 10:17 AM
	Why in three phase 440 circuit in all phase current is almost equal L1-35 A,L2-34 A ,L3-31 A but in nutral when i check with clamp meter it shows 25 A?
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Bill Guru Join Date: Dec 2005 Location: Clemson, South Carolina Posts: 1722 Good Answers: 18	#1 Re: Neutral current 05/15/2009 2:46 PM
	Could be due to harmonics. Can't tell from here. __________________ We have met the enemy and he is us . . . Walt Kelly
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wareagle Guru Join Date: Jun 2008 Location: Alabama Posts: 1604 Good Answers: 63	#2 Re: Neutral Current 05/15/2009 7:56 PM
	Maybe you used the wrong scale on the reading. To calculate the neutral current use following formula: √((Ia²+Ib²+Ic²)-(IaIb)-(IbIc)-(Ia*Ic)) Ia = Amp flow on phase A Ib = Amp flow on phase B Ic = Amp flow on phase C Ia = 35 Ib = 34 Ic = 31 My calculations resulted in 3.6 amps on the neutral.
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sb Guru Join Date: Mar 2007 Posts: 2550 Good Answers: 103	#3 In reply to #2 Re: Neutral Current 05/15/2009 9:33 PM
	The currents may be almost equal, but they need not be in phase. The neutral current is the vector sum and not the scaler sum (or subtractions) Assume the load power factors on different phases are different, then the currents will be unequally displaced in phase and you will have that readings, (ditto for voltage out of phase too) __________________ Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
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wareagle Guru Join Date: Jun 2008 Location: Alabama Posts: 1604 Good Answers: 63	#4 In reply to #3 Re: Neutral Current 05/15/2009 10:19 PM
	http://www.electrician2.com/electa1/electa4htm.htm Additional information
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keshi123 Active Contributor Join Date: May 2008 Posts: 17 Good Answers: 2	#5 Re: Neutral Current 05/24/2009 2:20 AM
	You have not mention, type of machine, if it is electronically driven, then there is a chance of statement made by SB. By normal rule, it should not be. In depth study will give you right answer, please check earth resistance also. bye
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Bill (1); keshi123 (1); sb (1); wareagle (2)

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