Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Relay coils polarity, why some matter and others dont ?
Relay coils polarity, why some matter and others dont ?
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 October 2019, 09:15 PM   #51
mchambin is offline mchambin  France
diyAudio Member
 
Join Date: Mar 2011
One point, I do not remember and I am pretty sure, here there are ones who know.
When there is a current surge in a winding, are the Laplace forces pushing the coils outward or inward ?
__________________
Transistor junction temperature is not transistor case temperature.
  Reply With Quote
Old 26th October 2019, 10:08 PM   #52
Mark Tillotson is online now Mark Tillotson
diyAudio Member
 
Join Date: May 2018
Location: Cambridge UK
Outwards. With an iron cored coil the coil forces are small compared with the forces between pieces of iron as only a small proportion of flux is outside the iron core.



Lines of flux act like elastic strings that repel one-another. Energy density in a field is proportional to the square of flux density, so spreading out field lines reduces density lowering energy, and shortening lines reduces the total volume of field, again reducing energy.
  Reply With Quote
Old 26th October 2019, 11:39 PM   #53
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Quote:
Originally Posted by zigzagflux View Post
.....V/turn is generally the same regardless of voltage or kVA (I seem to recall 8 V/turn being a generalized target for power transformers regardless of size).....
Hmmm. Not arguing, but at the hundred-VA size we can't go over 0.1V-0.2V per turn without problems. This value declines, slowly, with core size.
  Reply With Quote
Old 26th October 2019, 11:58 PM   #54
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
> pushing the coils outward or inward ?

The wreck looks "exploded". However the forces may be more complicated across the several windings and structures.
Attached Images
File Type: gif Winding-force-42.gif (20.4 KB, 30 views)
  Reply With Quote
Old 27th October 2019, 12:57 AM   #55
mchambin is offline mchambin  France
diyAudio Member
 
Join Date: Mar 2011
I had a coil exploded in my country house.
A coil in a remote switch, that was not working anymore.
May be from some stupid repair attempt, may be from a thunder lightning, but there was no burn or such traces, may be from an inappropriate operation under 230 V.
For sure the coil made of thin wire had an exploded look with several of them pried out.
Any idea ?
__________________
Transistor junction temperature is not transistor case temperature.

Last edited by mchambin; 27th October 2019 at 12:58 AM. Reason: 3
  Reply With Quote
Old 27th October 2019, 03:41 AM   #56
zigzagflux is offline zigzagflux  United States
diyAudio Member
 
zigzagflux's Avatar
 
Join Date: Oct 2006
Location: Charlotte, NC
Quote:
Originally Posted by PRR View Post
Hmmm. Not arguing, but at the hundred-VA size we can't go over 0.1V-0.2V per turn without problems. This value declines, slowly, with core size.
Will try to look it up, the materials go back 25 years from my previous employer, Waukesha Electric Systems (also under names Hevi Duty, ABB, Magnetek, North American Transformer, ASEA). I believe V/turn is proportional to core area iirc.
  Reply With Quote
Old 27th October 2019, 05:34 PM   #57
zigzagflux is offline zigzagflux  United States
diyAudio Member
 
zigzagflux's Avatar
 
Join Date: Oct 2006
Location: Charlotte, NC
A sample is attached. Fundamentally, it comes down to cost. As the size of the xfmr increases in VA, the copper loss becomes more cost-prohibitive than the core cost. So it becomes practical to increase the core cross sectional area in an effort to reduce the number of turns (increasing the V/turn and reducing the amount of copper).

This is in agreement with my experience in comparing small transformers we use in our amplifiers vs large power transformers measured in tens or hundreds of MVA. Small transformers have impedance largely dominated by resistance, whereas large transformers are largely reactive. They increase core size and crank up the V/turn, providing reactive behavior and limiting resistive losses.

Unfortunately I cannot find the 8 V/turn value anywhere; I suspect it was a particular unit I was studying at the time, likely in the neighborhood of 30 MVA base.
Attached Files
File Type: pdf xfmr.pdf (75.9 KB, 5 views)
  Reply With Quote

Reply


Relay coils polarity, why some matter and others dont ?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Filter component quality - do expensive coils and capacitors matter? Pygmy Parts 68 18th May 2018 03:37 PM
FS : Jantzen coils, Mundorf Coils, Mundorf ECaps gdan Swap Meet 4 21st November 2017 04:52 PM
Air-Core Moving Coil Cartridge Coils vs. Coils with permeable Cores tiefbassuebertr Analogue Source 0 31st August 2014 11:26 AM
Powering relay coils using +/- voltage spendorspain Parts 3 27th February 2008 08:32 PM
Does (primary) transformer AC polarity matter...? ptwining Class D 14 28th October 2006 01:19 PM


New To Site? Need Help?

All times are GMT. The time now is 07:29 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki