ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Recent Posts
VFD MotorFeeders
by gfretwell. 10/19/17 01:02 AM
Generator Cable Sizing
by brsele. 10/18/17 07:39 PM
What do you do?
by gfretwell. 10/17/17 01:08 AM
Good ol' copper pipe in the fuse holder trick
by HotLine1. 10/16/17 07:16 PM
Another generator question
by HotLine1. 10/16/17 07:02 PM
New in the Gallery:
Gallery Test
Popular Topics(Views)
241,415 Are you busy
177,387 Re: Forum
168,982 Need opinion
Who's Online Now
0 registered members (), 27 guests, and 7 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#130152 - 02/18/06 05:32 PM 3 phase wye neutral current  
randyagr  Offline
Junior Member
Joined: Mar 2004
Posts: 6
Lanark, IL US
Been trying to understand 3 phase wye neutral currents by reading this.http://www.allaboutcircuits.com/vol_2/chpt_10/2.html
Does this mean neutral current is the same for one 120v load and 2 120v loads, but drops to zero for 3 120v loads assuming all loads equal? Have only worked on 3 phase center tapped Delta in this area, so I know the neutrals cancel each other since both 120v legs are from the same phase, but I'm not sure I get this 3 Phase wye. Thanks, Randy


Tools for Electricians:

#130153 - 02/18/06 09:29 PM Re: 3 phase wye neutral current  
Larry Fine  Offline
Member
Joined: Feb 2005
Posts: 693
Richmond, VA
Randy, look at it mathematically: Start with an equal load, say 20 amps, on all three phases. The neutral current is the sum of the three currents, including the phase angles, which equals 0.

Now, remove the load on one phase, as well as its contribution to the neutral sum, -20 amps from each. This results in 20 amps subtracted from the previously-balanced zero neutral current, meaning 20 amps.

So that leaves 20 amps on two phases, and 20 amps on the neutral. Now, let's "check our math" by reversing the process: Each amp drawn by the third phase reduces the neutral current by the same amount, until it's back to zero.


Larry Fine
Fine Electric Co.
fineelectricco.com


Member Spotlight
JoeKP
JoeKP
Berkley, MA
Posts: 144
Joined: March 2008
Show All Member Profiles 
Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.010s Queries: 14 (0.002s) Memory: 0.7442 MB (Peak: 0.8647 MB) Zlib enabled. Server Time: 2017-10-20 21:46:54 UTC