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Transformer re-wire

spike47

Aug 11, 2009
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Transformer re-wire


Hi

We have a bit of a conundrum, we have ( our Model Club ) a Robin SmartPAT 3000 tester which developed a fault and we found out that there is a faulty micro thermal fuse located in between 2 layers of the Primary winding, so to get at it we had to first remove a Secondary winding that was laid on top of that , and one layer of the Primary winding, we have done that and replaced the fuse and rewound the second layer of the Primary winding, all is well up to now .


Now we want to rewind the Secondary winding , the winding that was on it was a sort of Litz type wire ( a bundle of 9 x 0.06mm ) soldered together at each end to a terminal , now I would say that if the 9 strands are soldered together , that would count has a single wire as far as turns are counted !.


So we counted all the single wires and divided them by 9 and come up with 175 turns for this particular Secondary output. ( some of the fine wire came away with the tape) so we just cut across the winding to remove it, not possible to count the turns .


We can’t source that type of wire, but we can use a single strand with the same mm2, but we can’t work out how that winding can produce 420v, if it was wound with the single individual strands ( ie not soldered together ) then that would equate to 420v !


Now according to the Manufacturers info this Transformer has the following :




Transformer Data:

TT1418: Trans-Sonic UK

Primary Winding : 230v – 120v
Secondary Winding: 420v @ 3mA.

We have wound a wire 175 turns of the same mm2 has the multi strand and it tested out has 57.6v .

We can source or make a separate transformer with a 420v output, but we just have to know how this one produced 420v, it just does not seem possible, unless this multi strand, although soldered in a 9 strand bundle, has some other weird way to produce that voltage .


Spike ( The Model Club )
 

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spike47

Aug 11, 2009
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So, is this a sister forum of that ?, I have not got the answer as yet, so does that mean I can't post the same query on another forum !.
 

bertus

Moderator
Nov 8, 2019
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Hello,

The AAC is the partner forum.
I posted the link, so members over here can see what already has been discussed.
There are more members that do have accounts on both forums.

Bertus
 

spike47

Aug 11, 2009
17
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Hello,

The AAC is the partner forum.
I posted the link, so members over here can see what already has been discussed.
There are more members that do have accounts on both forums.

Bertus
Yes, but also it was getting a bit messy , members answering without reading the original thread, so I thought I would make a fresh post about my problem, if they read the thread I have on the AAC it will confuse them, and then I will get responses from responses !.
Spike
 

spike47

Aug 11, 2009
17
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Mainly because the information given is muddled and not definitive.
Details have to be extracted.!

Yes , that may be, I am not a expert on Transformers or anything else for that matter, we are just a group who are members of a Model Club and trying to fix a transformer we have, I am just hoping there is some Einstein's out there that can extract the info for them to give me the answer !.
Spike
 

Minder

Apr 24, 2015
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Yes , that may be, I am not a expert on Transformers or anything else for that matter, we are just a group who are members of a Model Club and trying to fix a transformer we have, I am just hoping there is some Einstein's out there that can extract the info for them to give me the answer !.
Spike
As you were informed on the other site, multi conductors connected together are going to be considered a single conductor as far as a winding is concerned.
Also as told, You need to definitively obtain the turns/volt by placing a temporary 10turn over-wind and measure same!
 

spike47

Aug 11, 2009
17
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Aug 11, 2009
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Hi
Thanks for your reply, we put 175 turns on the Secondary, the same amount of turns the multi strand winding had and it measured 56.6v so that equates to 1 turn/0.32v !.
Cheers
Spike
 
Last edited:

roughshawd

Jul 13, 2020
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Basic electricity eg. electronics law says that any voltage that is split is considered equal to the source. that means if I take a wire, then split it into two wires that both those wires will have the same current. In order to reduce the voltage you have to divide the voltage also.
It seems like your transformer is punching through with a 230v source, and to increase that voltage on a secondary with induction you have to use a fusible link that is in the same aspect of the punch, so if you have 100 wraps of 230v then 50 wraps of induction should equal 460v...Shouldn't it? All schematics and electronic diagrams are called "Ideal circuits". That means if the circuit is perfect ie. IDEAL. BUT There is no such thing as a perfect circuit, you have to consider that any condition in any electrical current is just like any other condition in any other electrical circuit. That also means that power is not perfect and sometimes does strange things like climb across a grassy piece of lawn from an animal protection fence to your watering hose and cause you some kind of undue nervous attack....
I am a novice electronics student.
What they are telling me is that the draw from the device, must be equal to, or less than the source, if you don't want smoke. Serious.
 

Minder

Apr 24, 2015
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and to increase that voltage on a secondary with induction you have to use a fusible link that is in the same aspect of the punch, so if you have 100 wraps of 230v then 50 wraps of induction should equal 460v...Shouldn't it? .

You would have to explain that one to me!! :confused:
 

spike47

Aug 11, 2009
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Hello,

@roughshawd , is it not the other way around?
When the 230 Volts side has 100 wraps (turns) on the primairy side and the secondairy side is 50 wraps (turns), the secondairy voltage will be 115 Volts.
Have a look at this page:
https://www.allaboutcircuits.com/te...nt/chpt-9/step-up-and-step-down-transformers/

Bertus
That is a typical norm, for an EI transformer, the average is 3 to 5 turns/volt.

Hi
Thanks for your reply, I still don't have the answer for my conumdrum, the thing is I can make a 240v/420v Transformer quite easily, but before I do that I need to be sure of the query I mentioned in my post !, it is really bothering us, I have no idea why that winding is like that and why /how it produces 420v .
Spike
 

bertus

Moderator
Nov 8, 2019
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Hello,

You have stated the following:
Thanks for your reply, we put 175 turns on the Secondary, the same amount of turns the multi strand winding had and it measured 56.6v so that equates to 1 turn/0.32v !.
When 175 turns gives you 56.6 Volts, you can calculate the number of turns needed for 420 Volts:
(420 Volt / 56.6 Volt) X 175 turns = 1299 turns.

Bertus
 
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