ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
twh 10
Recent Posts
Windows 10, who's upgraded?
by geoff in UK. 05/29/17 01:05 PM
How do you find a good employee?
by ElectricianBud. 05/27/17 10:58 AM
Recall notice: Bosch Solar panels
by ElectricianBud. 05/27/17 10:53 AM
Correct rotation, wrong sequence
by Potseal. 05/27/17 12:15 AM
Dryer, Range grounding from "Main" panel
by sparkync. 05/25/17 05:49 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
237,002 Are you busy
172,019 Re: Forum
164,896 Need opinion
Who's Online Now
0 registered members (), 43 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#63103 - 03/06/06 08:45 PM secondary neutral  
circuit man  Offline
Member
Joined: Nov 2001
Posts: 273
saluda,s.c.
ok here is one that really has me puzzled.you have a 3 phase 14400 volt primary with no neutral.you feed a single phase dual bushing 7.2/14.4 pri to 120/240 secondary transformer. where do you get the system neutral? i know that the secondary has a midpoint & is also grounded to the can & pole. but what keeps this in line so to speak? THANKS!


Work Gear for Electricians and the Trades

#63104 - 03/06/06 09:03 PM Re: secondary neutral  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
"i know that the secondary has a midpoint & is also grounded to the can & pole."
You answered your own question....

"but what keeps this in line so to speak?"
From floating nuetral? There could be some float due to sever phase unbalace, but not by much.


Mark Heller
"Well - I oughta....." -Jackie Gleason

#63105 - 03/07/06 01:48 AM Re: secondary neutral  
wa2ise  Offline
Member
Joined: Nov 2002
Posts: 782
Oradell NJ USA
It doesn't really matter what the primary side is doing. But all you really want and need is good grounding of your neutral on the secondary side. That gets done at the pole, and also all the service entrances.

If the secondary wasn't tied to ground, capacitive coupling thru the transformer to the primary would create a substantial fraction of the primary voltage to appear on the secondary. Relatively high impedance, but more than enough to electrocute someone.


#63106 - 03/08/06 05:09 AM Re: secondary neutral  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Different voltage levels, but that's how all our transformers are wired in England, as we never have a neutral distributed with the HV lines.


#63107 - 03/08/06 12:36 PM Re: secondary neutral  
Radar  Offline
Member
Joined: Apr 2004
Posts: 349
Los Angeles, CA
Quote
where do you get the system neutral? . . . i know that the secondary has a midpoint & is also grounded

The grounded mid-point is your neutral, by definition. No (intended) connection between the primary and the secondary electrical systems.

Radar


There are 10 types of people. Those who know binary, and those who don't.


Member Spotlight
noderaser
noderaser
Portland, Oregon, United States
Posts: 404
Joined: March 2007
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.012s Queries: 14 (0.003s) Memory: 0.7681 MB (Peak: 0.9077 MB) Zlib enabled. Server Time: 2017-05-30 09:11:47 UTC