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
3 phase(240/120) delta bank #129481 03/30/05 10:19 PM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline OP
Member
Does this configuration have one transformer larger or smaller than the other two (due to the high-leg not being utilized for 120 volt loads)?

Tools for Electricians:
Re: 3 phase(240/120) delta bank #129482 03/30/05 11:10 PM
Joined: Oct 2000
Posts: 2,721
Scott35 Offline
Broom Pusher and
Member
Rojo-sy;

The 4 Wire Delta has a center Pot, which is sized according to the expected 120 VAC 1Ø 2 Wire (or combined 120/240 VAC 1Ø 3 Wire loads).

Larger center Transformers where more 1Ø 120 VAC needed, smaller where less is needed.

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Re: 3 phase(240/120) delta bank #129483 04/02/05 10:19 PM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline OP
Member
Thanks, Scott.
I thought I'd seen larger ones, then recently, I saw a smaller one. This explains it.

Re: 3 phase(240/120) delta bank #129484 04/04/05 04:05 AM
Joined: Apr 2002
Posts: 2,527
B
Bjarney Offline
Moderator
(…under construction…)

Truth is, four-wire delta banks can have any size transformers, including one “zero-size” pot—that being only two transformers—a/k/a an “open delta” bank. See IEEE std C57.105-1978 §6/§8 or odds’n’sods from EPE overhead standards linked at http://6l6.net/bjarn/EPEdelta-loadg.DSO7.pdf (~1MB) for some sizing guidelines (that are not necessarily NEC-based.) A ‘shorthand’ sketch of delta and open-delta secondary interconnection…

[Linked Image from 6l6.net]

 

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


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