Toroids, mounting bolts, and shorted turns - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

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 21st March 2004, 07:25 PM   #1
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
Default Toroids, mounting bolts, and shorted turns

Hi,

Just getting ready for BrianGT's Gainclone kit to get here, and I have a question. My toroidal transformer arrived from PArts Express, and it has 2 sets of mounting hardware (bolt, dished metal washer, foam/rubbery washer). I looked up shorted turns, and if I understand it right, I'll have a problem only if the bolt touches both the top and bottom plates, right? If I use both metal washers (one under the transformer and one on top), that won't cause a shorted turn. I think I have that right, but I'd just like to be sure before I connect power

I think it'll help to use the two foam washers, it'll probably isolate the transformer's vibrations from the chassis better? I'm not sure if there's any advantage to putting the second metal washer under the transformer though.

Thanks,
Saurav
  Reply With Quote
Old 21st March 2004, 07:30 PM   #2
andy_c is offline andy_c  United States
Banned
 
Join Date: Apr 2003
Hi,

There's a good illustration of the shorted turns issue here http://www.bcrn.com/Media/ToroidalPowerTransformers.pdf on page 6.
  Reply With Quote
Old 22nd March 2004, 01:42 AM   #3
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
Thanks. A picture always helps. I think I'm OK with using a metal mounting plate both on top of, and under, the transformer.
  Reply With Quote
Old 22nd March 2004, 12:08 PM   #4
BrianGT is offline BrianGT  United States
diyAudio Moderator Emeritus
 
BrianGT's Avatar
 
Join Date: Jan 2002
Location: near Atlanta, GA
Send a message via AIM to BrianGT
Quote:
Originally posted by Saurav
Thanks. A picture always helps. I think I'm OK with using a metal mounting plate both on top of, and under, the transformer.
I am using a metal plate on top of my transformer, with a bolt going through it, touching both the plate and my chassis bottom. This hasn't caused me any problems.

I guess it would become a problem if you grounded the top plate someway besides the bolt, creating a loop like in the picture.

--
Brian
Attached Images
File Type: gif transformer-shorted.gif (9.2 KB, 500 views)
  Reply With Quote
Old 22nd March 2004, 02:43 PM   #5
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
I was thinking of sending the earth connector of the IEC plug to that top plate, since it's a nice thick nut/bolt and should make a good star ground point. That should still be OK though. The IEC earth prong isn't connected to the chassis anywhere else, and it's the bolt that connects the chassis to earth here. So, that shouldn't create a loop either.

I hope
  Reply With Quote
Old 22nd March 2004, 02:52 PM   #6
Warp Engineer
On Holiday
 
AudioFreak's Avatar
 
Join Date: Oct 2001
Location: Queensland, Australia
Basically, if you cant map a path of electrically conductive material that forms a loop going thru the centre of the toroid then you should be safe from shorted turns external to the toroids insulation. Doesn't matter if both the top and bottom washers are conductive as long as the only path of conduction between them is thru the mounting bolt going thru the centre of the toroid.
__________________
- Dan
  Reply With Quote
Old 22nd March 2004, 08:17 PM   #7
lgreen is offline lgreen  United States
diyAudio Member
 
lgreen's Avatar
 
Join Date: May 2003
Location: San Diego, USA
Default Shorted Turn indicators?

In my GC, the tansformer bolt is very close to the top cover. but the transformer is isolated from the metal chassis by a rubber pad, and the top plate of the mounting assembly is isolated from the transformer via a rubber pad. Neverless, when I push down on the chassis of my GC (when "on"), the top metal cover hits the transformer bolt, this causes a very loud vibration and the area of contact immediately gets too hot to touch.

Is this "shorted turn?" The issue has been solved by using a shorter xformer bolt.
  Reply With Quote
Old 22nd March 2004, 09:50 PM   #8
tja is offline tja  Netherlands
diyAudio Member
 
Join Date: Feb 2004
Location: Leiden
Yup, that's the shorted turn. The bolt through the center of the transformer is forming a loop with the chassis, with almost no resistance I should think, therefore the current can be quite high, thus generating the heat.

Take
  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
mounting toroids neil_kaye Parts 4 15th November 2006 08:02 AM
shorted turns in primary? mrshow4u Solid State 15 12th September 2006 05:09 PM
Mounting toroids with little to no room for bolt ThingyNess Parts 24 27th February 2003 07:54 AM
Winding toroids, turns vs core area johan Parts 2 28th September 2001 08:44 AM


New To Site? Need Help?

All times are GMT. The time now is 05:59 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