TPN or 4-Pole

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j_kamal Associate Join Date: Jan 2008 Location: India Posts: 43 Good Answers: 2	TPN or 4-Pole 02/25/2008 4:33 AM
	Hi, I am considering renovation of a old LV distribution panel having 3-Pole and a reduced neutral busbars having 800 Amp rating, the configuration of the panel is - 1. Main Incomer ( 240 Sq mm 3.5 core,1100 V XLPE Aluminuc cable) - 400 Amp ICTPN switch 2. 8 outgoing through ICTPN switches of 300 and 200 Amp rating. I would like to request comments on whether I should go for a TPN busbar arrangement or 4-Pole. The presently installed distribution panel is having copper busbars whereas I am thinking for 4-Pole Aluminum busbars with larger section as also 4-Pole MCCBs, 'coz space is not a constraint. I have observed problems in digital panel meters; would it be good to have analog meters. Finally what should be the voltage (mili volt) drop between the cable conductor and end termination (Cable lug) after energizing. Regards, Kamal __________________ It takes considerable knowledge just to reaIise your own extent of ignorance.
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biswanath.das Power-User Join Date: Oct 2006 Location: Kolkata, India Posts: 447	#1 Re: TPN or 4-Pole 02/25/2008 7:48 AM
	Go for TPN. Milivolt drop may be max 70. But try to keep below 20. You can consult breaker manufacturer to get their view. __________________ BNDas
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nambiathiri Active Contributor Join Date: Jan 2008 Posts: 18	#2 Re: TPN or 4-Pole 02/25/2008 10:49 PM
	If the system is TT, better to go for 4pole. If there are non linear loads having harmonic content neutral bus size shall be at least same as phase buses
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Anonymous Poster	#3 In reply to #2 Re: TPN or 4-Pole 02/26/2008 12:44 AM
	Thanks Nambiathiri, I appreciate your comments. Almost 45 percent of the connected load is non-linear, I would rather go for 4-pole arrangement. Regards, Kamal
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Anonymous Poster	#4 Re: TPN or 4-Pole 02/26/2008 6:48 AM
	In an unbalanced 3-ph system or a system with non-linear loads,the neutral gives the safety to the unbalanced loads in the system and therefore must not be neglected.Even in perfectly balanced conditions the neutral functions as a safety conductor in the unforseen short-circuit and fault conditions.Therefore i would advise a 4-pole arrangement would enhance the system.
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Anonymous Poster (2); biswanath.das (1); nambiathiri (1)

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