The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
230 or 345 kV transmission lines?
by Vlado
09/24/16 09:33 AM
breaker meltdown
by crselectric
09/24/16 12:42 AM
Electrical mast flashing product
by ThomasWinfrey
09/22/16 12:14 AM
What estimating software do you recommend?
by sparky
09/21/16 07:20 PM
"Dry Run" Inspection goes awry
by HotLine1
09/20/16 07:39 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
HotLine1 15
sparky 9
gfretwell 8
sparky66wv 8
Vlado 6
Who's Online
1 registered (Icarus), 177 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#211368 - 10/08/13 04:20 PM Need quick help from a transformer guy
Steve Miller Offline
Member

Registered: 08/30/01
Posts: 322
Loc: Loudoun Cty, VA
We have a 3 phase 208Y120 feed and need to boost to power a single phase 240 unit. I personally have not seen the unit but the guys tell me it's a 'Big Screen' display (scoreboard). The question is: can we use a single BB xfmr and follow the basic 208-240 diagram which basically puts everything in series or do we need 3 BB xfmrs and simply use only 2 of the outputs? My concern is that the 208Y will feed the BB from 2 diff xfmrs. Will it cause a phase shift and cook my (single) BB xfmr?

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#211381 - 10/08/13 07:59 PM Re: Need quick help from a transformer guy [Re: Steve Miller]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6785
Loc: Brick, NJ USA
Steve:
I do not profess to be a transformer guru, but, I have run a lot of 240 single phase via a BB xfr from 120/208 3 phase 'Y' systems with no issues.

That said, none of the stuff I ran was electronics.

Scott35 & Greg?? Help
_________________________
John

Top
#211386 - 10/08/13 09:58 PM Re: Need quick help from a transformer guy [Re: Steve Miller]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
I don't see a problem but I am just guessing. All of our equipment would run 208 or 240, either by tapping the input or just that it had a wide enough mouth.
I think it will be seen as just another 1p L/L load.
_________________________
Greg Fretwell

Top
#211413 - 10/10/13 12:42 PM Re: Need quick help from a transformer guy [Re: Steve Miller]
Steve Miller Offline
Member

Registered: 08/30/01
Posts: 322
Loc: Loudoun Cty, VA
The rest of the story ....
Here's what I didn't know at original post time:
They did cook the BB xfmr (that's why the development of the question about potential for a phase shift that I posted). Seems as tho the board needed 2 hots, neutral and ground because it's basically nothing but a big multiwire ckt and needs the neutral. It came from factory with these 4 tails attached and labeled. The sign guy on top of the ladder told our guy 240 volts ... period. No mention of the neutral and our guy didn't go up and look or question it (strike one). So they hooked up a BB, did not pass the system neutral through (strike two) and fused the primary using the proper fuse size for the secondary (strike three). Guess what smoked. We got lucky it was the xfmr, not the board.
Thanks for the help and we got the guys straight. Nice video board.

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals