transformer wiring causing brain melt down - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th July 2010, 09:36 PM   #1
diyAudio Member
 
Join Date: Jun 2010
Default transformer wiring causing brain melt down

I have come by a transformer which has 2 primary windings of 115 volts . There are 3 wires to the primary windings. 2 brown and 1 white. I take it the white is a shared o volts or ground /center tap. I live in the UK where domestic mains is 230/240v. I am trying to figure out how to wire this to the mains.If both primary windings have a common ground , I cant see how I can wire the two coils in series?? The only possible way i can suppose is to wire both brown wires one to live and one to neutral and the shared white to mains earth???? Is this right?surely not? as each coil would alternate at 240v , which each is not rated for.I am totally confused can any one help?
  Reply With Quote
Old 26th July 2010, 10:04 PM   #2
diyAudio Member
 
Join Date: Jan 2008
Location: Carp
first, ohm out the coils
  Reply With Quote
Old 26th July 2010, 10:09 PM   #3
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
I would guess the white is the center tap.

For 115 volts the two browns go to live and the white goes to neutral.

For 240 volts the live goes to one brown and the neutral goes to the other brown with white left floating.
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 26th July 2010, 10:10 PM   #4
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Maybe it's a foreign transformer where earth is a centre tap, so you only ever get 115V max above earth for safety reasons. If so then you can connect it to mains but you must insulate the white wire, if you connect it to earth it will blow the transformer and house electricity supply as you will be putting 115V onto house earth.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 26th July 2010, 10:29 PM   #5
diyAudio Member
 
Join Date: Jun 2010
well white to either brown is 14 ohms resistance:brown to brown is 28 ohms . I guess white must be centre tap. So it is left floating, i can see why now :the white wire is basically the end of the first winding AND the start of the second, ie to connect to 240 mains if you isolate the white wire the two windings are already in series. thanks for the help.
  Reply With Quote
Old 26th July 2010, 10:32 PM   #6
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Quote:
Originally Posted by chokesrule View Post
well white to either brown is 14 ohms resistance:brown to brown is 28 ohms . I guess white must be centre tap. So it is left floating, i can see why now :the white wire is basically the end of the first winding AND the start of the second, ie to connect to 240 mains if you isolate the white wire the two windings are already in series. thanks for the help.
Whoa, that's a lot of resistance for a primary. Are you sure you're not confusing the secondaries with the primaries? How many and what resistance are those?
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 28th July 2010, 10:02 PM   #7
diyAudio Member
 
Join Date: Jul 2010
Location: Colorado
It would be unusual for a 115/230 volt primary to be center tapped. For 115V operation the primaries must be in parallel, with the "start" of winding 1 connected to the "start" of winding 2 for proper phasing. For 230V operation the windings are connected in series, with the "start" of winding 2 connected to the "finish" of winding 1. This means all four wires need to be brought out. The center tapped configuration is much more common as a secondary winding.
  Reply With Quote
Old 28th July 2010, 10:32 PM   #8
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
what is printed on the manufacturer's label?
__________________
regards Andrew T.
  Reply With Quote
Old 28th July 2010, 10:43 PM   #9
diyAudio Member
 
Steerpike's Avatar
 
Join Date: Jan 2006
Location: Johannesburg, South Africa
Seems like it could be just a 0V-110v-220v winding - nothing too odd. Brown+white for 110, brown+brown for 220. At 110V only one half the winding will be used, which is inefficient, but not that uncommon. The colour coding is odd though - they would normally be 3 different colours.
__________________
Steerpike's Toybox

Last edited by Steerpike; 28th July 2010 at 10:46 PM.
  Reply With Quote
Old 28th July 2010, 10:51 PM   #10
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
could it be a 55,0,55Vac (=110Vac) isolating transformer for industrial and outdoor tool use?
__________________
regards Andrew T.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
solder won't melt whojohnjones Car Audio 5 26th July 2010 03:07 AM
How to wiring the transformer olaychang Tubes / Valves 7 2nd February 2009 05:07 AM
Transformer Wiring? Killjoy99 Parts 4 2nd October 2004 11:00 PM
transistor melt down ? mikelm Solid State 24 27th January 2004 09:20 PM


New To Site? Need Help?

All times are GMT. The time now is 11:13 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2