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Posted By: Trumpy Toroidal Transformers? - 03/22/03 05:03 AM
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-
Posted By: Scott35 Re: Toroidal Transformers? - 03/22/03 08:34 AM
Trumphy,
I'll take the first leap [Linked Image]...

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
Posted By: Bjarney Re: Toroidal Transformers? - 03/23/03 12:50 AM
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.

[Linked Image from 67.115.161.42]

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).]
Posted By: pauluk Re: Toroidal Transformers? - 03/23/03 01:24 PM
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.
Posted By: iwire Re: Toroidal Transformers? - 03/23/03 01:38 PM
Bjarney

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

I am sure there is some intresting stuff in there.

Bob
Posted By: Bjarney Re: Toroidal Transformers? - 03/23/03 03:55 PM
iwire — Trouble is, there's 2½ inches of dust on everything. ;-)
Posted By: Trumpy Re: Toroidal Transformers? - 03/24/03 06:48 AM
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. [Linked Image]
Posted By: Scott35 Re: Toroidal Transformers? - 03/25/03 12:56 AM
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???? [Linked Image]...)

Scott35
Posted By: Bjarney Re: Toroidal Transformers? - 03/25/03 02:53 AM
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…}
Posted By: pauluk Re: Toroidal Transformers? - 03/25/03 09:14 AM
Quote
Prices for the Mega-Lite systems start at $38,995.00

[Linked Image]

Only residents of CA 90210 need apply?? [Linked Image]

Reckon you could put it on an east-facing wall Scott? I might benefit from some of the light spillage over here! [Linked Image]
Posted By: Bjarney Re: Toroidal Transformers? - 03/25/03 08:44 PM
I'm thinking that floating a metalized-mylar hydrogen balloon over the New Jersey coast might do it. Would 120,000 feet of string be about right?
Posted By: C-H Re: Toroidal Transformers? - 03/25/03 09:13 PM
Are you throwing a party for the kids and want something that beats the ordinary party balloons?
Posted By: Bjarney Re: Toroidal Transformers? - 03/25/03 09:22 PM
Any reflective 600-foot baloon should do it.
Posted By: Trumpy Re: Toroidal Transformers? - 04/03/03 09:26 AM
Bjarney,
16kW!! [Linked Image]
I should be able to see that over here in NZ! [Linked Image]
Assuming that you are running it on 120V, it will draw 134A, how big's your flex?!. [Linked Image]
Posted By: pauluk Re: Toroidal Transformers? - 04/03/03 01:06 PM
I think that one would rate being a 240V design! [Linked Image]
Posted By: Trumpy Re: Toroidal Transformers? - 04/04/03 12:09 AM
Thanks Paul,
That would be hard on the Power Bill!. [Linked Image]
Posted By: Bjarney Re: Toroidal Transformers? - 04/04/03 04:59 AM
Er, the 10kW single-lamp version is listed as "208/480 volt, 3 phase power supplies". There just has to be a 380-415V 'export version' available.

Right now, the homestead has a whopping 125-amp 120/240V service. {The “new and improved” 20,780Y/12,000V utility feed with 3750kVA padmount transformer is due next week.}
Posted By: pauluk Re: Toroidal Transformers? - 04/04/03 09:46 AM
Gee, BJ, are you trying to give California another power crisis all by yourself?! [Linked Image]
Posted By: Trumpy Re: Toroidal Transformers? - 04/04/03 11:49 AM
Bjarney,
No point in doing things by halves, eh?
If you're gonna do it, DO IT!. [Linked Image]

[This message has been edited by Trumpy (edited 04-04-2003).]
Posted By: Bjarney Re: Toroidal Transformers? - 04/04/03 05:11 PM
The big electric service is for my surplus 2200-ton chiller. {Summers are hot locally.} If my arithmetic is correct, then running the chiller for 2.7 seconds each day will keep the house cool for 24 hours. ;-)
Posted By: Trumpy Re: Toroidal Transformers? - 04/04/03 11:47 PM
WOW!!
The only way to go, just don't accidentally leave it on for an extra second, mate, you'll freeze the family! [Linked Image]
Posted By: Bjarney Re: Toroidal Transformers? - 04/05/03 02:01 AM
Only one problem I did not anticipate — just found out my new electric meter doesn’t register kilowatthours, but megawatthours {!}
Posted By: Trumpy Re: Toroidal Transformers? - 04/05/03 08:18 AM
BJarney,
Hope you've got some good CT's on that installation!
We're talkin' 1:1000 ratio here.
Over here, you would have your own Tranny, most probably 5MVA, fed with either 11,22 or 33kV, but to have this sort of supply capacity, you have to live out in the sticks, mate.
And you are fed with(depending on your load)
3Phase+Neutral 16mm2, the size of the installation is judged by the size of the fusing, this is what you are charged for.
Posted By: Bjarney Re: Toroidal Transformers? - 04/06/03 12:03 AM
Good point, Trumpy. There's a 115kV line only 1.3 miles to the east of here. Now, if I could just find a little extra room for my switchyard.

{There is a new casino in Las Vegas that has a 115- or 138kV loop, with a pair of 60,000kVA transformers. I can dream, can't I?
Posted By: pauluk Re: Toroidal Transformers? - 04/06/03 10:26 AM
Wow, that's some casino! I guess they must be trying to compensate for the vast areas of Nevada that have nothing to use power at all! [Linked Image]
Posted By: Trumpy Re: Toroidal Transformers? - 04/09/03 08:52 AM
Bjarney,
I don't think I would like living next door to an installation like that, the 60Hz hum would drive me crazy, and there would be a fair bit of it, at 115kV. [Linked Image]
And apparently, some people complain(who live adjacent to EHV lines), that thier lights still go after the wall switch has been turned off!. [Linked Image]
Posted By: pauluk Re: Toroidal Transformers? - 04/09/03 05:29 PM
Hey, free power!

I recall reading about someone who lived right next door to a very powerful shortwave broadcast transmitter (in Switzerland, if I recall correctly). He installed suitable pickup coils around the house to get free lighting! [Linked Image]
Posted By: Bjarney Re: Toroidal Transformers? - 04/09/03 06:15 PM
I have heard that radio-tower painters work at night holding a fluorescent tube in one hand.

[What that has to do with toroidal transformers I'll never know.]


[This message has been edited by Bjarney (edited 04-09-2003).]
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