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#136201 - 03/21/03 09:03 PM Toroidal Transformers?
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
Toroidal trannys, these are hailed as the future of Transformers, as we know them.
Less I2R losses, less EMI, single bolt mounting, they run cooler too.
Most of the good quality stereo equipment uses this sort of Xformer, as opposed to the E-I configuration, which is high in losses and they have a poor regulation factor(P-S).
Would anyone like to jump into the waters of this argument, it has been a really hot topic,regarding safety standards, here DownUnder?.
Your thoughts please-
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#136202 - 03/22/03 12:34 AM Re: Toroidal Transformers?
Scott35 Offline

Broom Pusher and
Member
Registered: 10/19/00
Posts: 2707
Loc: Anaheim, CA. USA
Trumphy,
I'll take the first leap ...

I like Toroids. They "Hold" their fields much better than their Laminated "E" Core & bobbin counterparts (the magnetic field interaction is greatly reduced with Toroids - like when 2 or more are mounted close together).

They are used in Switch Mode Power Supplies (SMPS) for all Inductive elements (other than the AC Line filter - it's Inductor section is one of those "Back-to-Back zero sequencing coil arrays).

Toroids also used in Electronic High Hz Fluorescent Lighting Ballasts. The Controlled Reactors are tapped toroids.

TVSS w/ Line filters also incorporate Toroid wound Inductors.

I use Toroid wound air core Inductors in Audio system crossover networks (Passive Filtering of Speakers).
Either Toroids, or Perfect Layer stacks (also air core).

The major pain as far as Toroids go is how hard they are to wind yourself!!! My Brother-In-Law brought home a Toroid winding machine, so maybe I could use it for awhile.

Standard Core/Coil setups are relatively simple, compared to hand winding Toroids!

Oh, the largest Power Toroid Transformer I have seen so far must have been in the 5 KVA range. It was an Isolated Type setup, with 2 wire primary and a center tapped secondary.
I figure it was 5 KVA form it's physical size:
Apx. 6" Diameter ring with maybe #12 or #11 windings.

My Practical Transformer Design Handbook briefly covers the design data of toroids.

Scott35
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Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
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#136203 - 03/22/03 04:50 PM Re: Toroidal Transformers?
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
Electrical work would be a lot less interesting if it weren’t for 47-pound donut {window} current transformers. They make gnarley low-voltage, high-current transformers using a piece of 4/0AWG welding cable. With a powerstat and the right timer they work well for testing smaller circuit breakers and motor-overload relays.



A 600:5 class-C200 CT is good for initial experimenting.
http://www.geindustrial.com/products/specs/143.pdf



[This message has been edited by Bjarney (edited 03-22-2003).]
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#136204 - 03/23/03 05:24 AM Re: Toroidal Transformers?
pauluk Offline
Member
Registered: 08/11/01
Posts: 7520
Loc: Norfolk, England
Toroidal transformers have indeed become popular in recent years.

There are one or two things to watch when designing with them though. First, the nature of the toroid which results in low EM leakage also results in quite large switch-on surges, much larger than for an equivalent size "conventional" xfmr. Anti-surge ("slow-blow") fuses are often necessary in the primary.

Second, you have to watch that mounting bolt. It may be tempting in some design to use it to help anchor other devices, brackets, etc., but it must be remembered that the bolt passes through the center of the toroid, and any metallic path created by hanging extra hardware on it is outside the toroid. It will form a shorted turn, and result in a large current circulating through the bolt and external hardware.
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#136205 - 03/23/03 05:38 AM Re: Toroidal Transformers?
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Bjarney

I would like to see your workshop, garage or basement.

I am sure there is some intresting stuff in there.

Bob
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Construction & Maintenance Electrician
Massachusetts
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#136206 - 03/23/03 07:55 AM Re: Toroidal Transformers?
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
iwire — Trouble is, there's 2½ inches of dust on everything. ;-)
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#136207 - 03/23/03 10:48 PM Re: Toroidal Transformers?
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
In an age that requires EMC(Electromagnetic Device Compliance), I would sooner go for the Toroidal Tranny!.
Paul, very good point about the mounting stud, you are just asking for trouble, if you start running other things under the dish-plate, that secures the tranny.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
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#136208 - 03/24/03 04:56 PM Re: Toroidal Transformers?
Scott35 Offline

Broom Pusher and
Member
Registered: 10/19/00
Posts: 2707
Loc: Anaheim, CA. USA
Bob ("Iwire"),

Quote:

Bjarney

I would like to see your workshop, garage or basement.

I am sure there is some intresting stuff in there.

Bob


You've got that right!!! I might just show up one day at Scott's (Bjarney's) front door!!!

Scott/Bjarney: if you have home CCTV equipment, better set it up to "Profile" me!!! Then when I show up at your door, and it's 3:30 AM, you can both avoid answering the door and set the trap door for autotrigger!
(I am only kidding about showing up un-announced!....or am I???? ...)

Scott35
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
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#136209 - 03/24/03 06:53 PM Re: Toroidal Transformers?
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
I'll send you all gilt-edged invitations the moment I get my new porch light running—a Tek “Mega” 16kW 4-lamp xenon-arc rotating cluster, with the deluxe quad-30-inch reflector upgrade. http://www.teklighting.com/search.html {Any year now…}
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#136210 - 03/25/03 01:14 AM Re: Toroidal Transformers?
pauluk Offline
Member
Registered: 08/11/01
Posts: 7520
Loc: Norfolk, England
Quote:
Prices for the Mega-Lite systems start at $38,995.00




Only residents of CA 90210 need apply??

Reckon you could put it on an east-facing wall Scott? I might benefit from some of the light spillage over here!
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