ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Unusual Well Pump Switch Failure
by sabrown - 10/28/20 04:31 PM
Look at this mess...
by InspectorE - 10/27/20 09:09 PM
New tool
by gfretwell - 10/24/20 11:09 AM
Where is Everyone?
by Bill Addiss - 10/17/20 07:04 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 21 guests, and 13 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
single phase from three phase #129284 01/03/05 11:33 AM
Joined: Mar 2004
Posts: 6
R
randyagr Offline OP
Junior Member
Let's say I have a v-phase primary (2 hots plus a nuetral) with a 3 phase center tap open delta service drop(3 hots plus a nuetral) Each phase is 120 degrees apart, but if I take 2 leads for a sigle phase application, the phases are 180 degrees apart. How does this happen? Also, how many degrees apart are the phases on the primary? Thanks. Randy.

Tools for Electricians:
Re: single phase from three phase #129285 01/03/05 11:37 PM
Joined: Sep 2003
Posts: 649
W
winnie Offline
Member
I just about wrote an essay related to this topic last week: https://www.electrical-contractor.net/ubb/Forum7/HTML/000358.html

You cannot define phase angle with a single circuit. You only get a phase angle measurement when you have _two_ or more circuits, and can describe the phase angle difference between them.

If you supply a single phase line to line load from a three phase source, than as far as that load is concerned, there is no phase angle. You only have two terminals, with first one then the other alternatively being relatively positive.

Once you have two circuits defined, _then_ you can find a phase angle difference. With your 'V' primary, you have three circuits; neutral to A, neutral to B, and A to B. If we _define_ the phase of the neutral to A circuit as zero degrees, then the neutral to B circuit is 120 degrees. I believe that the A to B circuit has a phase angle of 150 degrees with an amplitude of 1.732 * the amplitude of the neutral to A circuit, but I'm not going to swear to that without doing the math out on paper.

-Jon

Re: single phase from three phase #129286 01/04/05 12:25 AM
Joined: Apr 2002
Posts: 2,527
B
Bjarney Offline
Moderator
 
For an open-delta secondary, there are two possible configurations for the primary side of the transformer bank. One is open-wye, with 120° between two phase-to-neutral primary connections. The other is open-delta, with 60° between two phase-to-phase-connected primary windings, that are typically symmetrical with the two secondary windings.

http://www.cooperpower.com/Library/pdf/R201902.pdf
http://shop.ieee.org/ieeestore/Product.aspx?product_no=SS6924




[This message has been edited by Bjarney (edited 01-04-2005).]


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Radar
Radar
Los Angeles, CA
Posts: 349
Joined: April 2004
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
271,026 Are you busy
205,035 Re: Forum
193,143 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3