UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Components and Circuits

Notices

Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

Closed Thread
 
Thread Tools
Old 23rd Mar 2023, 7:25 pm   #1
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Square wire in transformers.

In times-past I came across a few transformers made by the US company 'Stancor' which employed an intriguing construction.

They were obviously designed to be 'modular' in that a set of up to 4 bobbins could be stacked on the centre leg of a classic E/I core; the ones that particularly come to mind had a 3-bobbin setup with the primary split into two halves which occupied the outer sides of the 'middle wicket', the secondary sat between them - and the interesting thing was that for a particularly high-current application the secondary was wound with *square* wire, presumably to get the maximum copper-cross-sectional-areainto the available space to minimise losses though I never saw this documented as the reason.

I _do_ remember the description of some of these transformers stating that they were intended to saturate under particular startup conditions though, a bit like the HT/LT transformers in first-generation microwave-ovens,.

Only other place I have come across square-wire windings is in legacy electric-welder units [the type with a big handwheel on the front to control the current] - in those cases the square-wire secondary was often aluminium!
__________________
I'm the Operator of my Pocket Calculator. -Kraftwerk.
G6Tanuki is online now  
Old 23rd Mar 2023, 8:32 pm   #2
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
Default Re: Square wire in transformers.

I think the square wire was called "magnet wire", possibly from its use in electromagnets.
emeritus is offline  
Old 23rd Mar 2023, 9:03 pm   #3
TowerRadio
Hexode
 
Join Date: Mar 2008
Location: Bristol, UK.
Posts: 388
Default Re: Square wire in transformers.

The voice coil type of positioner in some disk pack drives used square section aluminium windings.Les.
TowerRadio is offline  
Old 23rd Mar 2023, 9:08 pm   #4
kellys_eye
Octode
 
Join Date: Jan 2014
Location: Oban, Scotland, UK.
Posts: 1,118
Default Re: Square wire in transformers.

I have a transformer for an old inverter (UPS) that has 'oval' wire. Not exactly square but a lot flatter than round. Clearly it's a high current secondary and I'd love to re-purpose the wire but I can't get the laminations apart.
kellys_eye is offline  
Old 23rd Mar 2023, 9:34 pm   #5
broadgage
Nonode
 
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
Default Re: Square wire in transformers.

Rectangular section wire is almost always used in utility sized transformers.
https://www.youtube.com/watch?v=Q69QOwVbzjY

Shows the assembly of a utility scale transformer and the materials used.

Rectangular section wire is more expensive to manufacture, but this is justified for large transformers as it saves space.
broadgage is offline  
Old 23rd Mar 2023, 11:46 pm   #6
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
Default Re: Square wire in transformers.

Just did a search for "square copper wire". It is sold by craft suppliers for use in making jewellry, and is also available in other metals. "Magnet wire" seems to be a synonym for ordinary varnished copper wire.

Last edited by emeritus; 24th Mar 2023 at 12:03 am. Reason: typos
emeritus is offline  
Old 23rd Mar 2023, 11:57 pm   #7
Silicon
Nonode
 
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,152
Default Re: Square wire in transformers.

Tape profile wire is probably easier to bend compared to the equivalent square section wire.
Silicon is offline  
Old 24th Mar 2023, 12:06 am   #8
kalee20
Dekatron
 
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,061
Default Re: Square wire in transformers.

I've been involved in square-section (0.5mm square) enamelled silver wire for the ultimate low resistance.

Price is rather scarey though!
kalee20 is online now  
Old 24th Mar 2023, 12:07 am   #9
Leon Crampin
Octode
 
Join Date: Nov 2005
Location: Surrey, UK.
Posts: 1,869
Default Re: Square wire in transformers.

Rectangular section wire is used in most high powered automotive starters and alternators. The 50VA or so lamp transformer in my old Braun slide projector also has rectangular section wire for the secondary winding. The packing factor benefits are considerable.

Leon.
Leon Crampin is offline  
Old 24th Mar 2023, 12:09 am   #10
retailer
Heptode
 
Join Date: May 2005
Location: Adelaide, South Australia
Posts: 541
Default Re: Square wire in transformers.

Here's the rectangular X-section windings pulled from a biggish transformer that was part of an off grid inverter, 24VDC to 240AC, switching was done by paralleled TO220 Mosfet's I haven't counted but possibly up to 60 Mosfet's in total. The EI transformer centre leg is approx 55mm wide, stack height approx 90mm lamination are 0.35mm thick each I've given the core to an acquaintance - he intends to make a pair of 'ultimate' SE triode amp output transformers, once he has the design finalised he'll pass it on to me for winding. I'm not convinced of the need for such a big core.
Attached Thumbnails
Click image for larger version

Name:	20230324_091746.jpg
Views:	95
Size:	39.0 KB
ID:	275632   Click image for larger version

Name:	20230324_091753.jpg
Views:	89
Size:	40.4 KB
ID:	275633  
retailer is offline  
Old 24th Mar 2023, 10:50 am   #11
kellys_eye
Octode
 
Join Date: Jan 2014
Location: Oban, Scotland, UK.
Posts: 1,118
Default Re: Square wire in transformers.

Must be difficult to maintain the insulation properties at the sharp edges of the square wire. Might be why the 'oval' (rounded edge - not quite square) wire in my transformer was used?
kellys_eye is offline  
Old 24th Mar 2023, 1:15 pm   #12
kalee20
Dekatron
 
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,061
Default Re: Square wire in transformers.

I don't know about rectangular... but the square silver stuff I referred to earlier, is manufactured as round enamelled wire and goes through rollers to create the square profile.

I'd guess that trying to get an even enamel build-up on bare square wire could be difficult!

Incidentally, enamelled rectangular copper wire, of even fairly extreme aspect ratio (4:1 width:thickness), can be wound edgewise with a suitable forming tool, without the enamel splitting. I've done it!
kalee20 is online now  
Old 24th Mar 2023, 1:45 pm   #13
Lucien Nunes
Rest in Peace
 
Join Date: Apr 2008
Location: London, UK.
Posts: 2,508
Default Re: Square wire in transformers.

Also used in machine armature coils that are made on a former, taped and fitted into the slots. In these applications the mechanical forces acting on the coils can be considerable so they are bound tightly, with suitable insulation between layers if required, to make each coil a mechanically robust assembly. Rectangular section copper not only improves current density, but improves the dimensional accuracy and stability.
Lucien Nunes is offline  
Old 24th Mar 2023, 1:50 pm   #14
duncanlowe
Nonode
 
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,529
Default Re: Square wire in transformers.

I've come across it in loudspeaker voice coils. Claimed to be to improve power handling.
duncanlowe is offline  
Old 24th Mar 2023, 2:07 pm   #15
Roger Ramjet
Heptode
 
Join Date: Feb 2022
Location: Leicestershire, UK.
Posts: 690
Default Re: Square wire in transformers.

I remember square wire on the rotating field winding of a 125kVA 3 phase alternator that had to be rewound during the miners strike / 3 day working week.
Roger Ramjet is offline  
Old 24th Mar 2023, 2:09 pm   #16
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,800
Default Re: Square wire in transformers.

Square wire isn't exactly square. Corners have to be rounded and smooth to allow for uniform varnish coating.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline  
Old 24th Mar 2023, 5:52 pm   #17
Malcolm G6ANZ
Octode
 
Malcolm G6ANZ's Avatar
 
Join Date: Feb 2006
Location: Bristol, UK.
Posts: 1,030
Default Re: Square wire in transformers.

In the linacs I used to work with the electromagnets used to steer the beam of electrons were wound with square section copper tube. Water was pumped through the magnets to keep them cool, they were running at 80-120A. The feed cables were the size of welding cables. They were supplied from a regulated and programmable 3phase supply.
Happy days
Malcolm G6ANZ is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 9:45 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.