Transformer rewind wire query

[Spike1947]

Hi
I have a Transformer, that needs a rewire on a Secondary windings, the wire that was on it, was a muti-core wire 9 strands, (0.06mm x 9) ( each strand enameled ), soldered together at each end, and laid on top of the primary winding with 175 turns, with a copper tape between the primary and this secondary .

Question: This multi core (Litz) secondary winding is supposed to have a output of 420v, but with only175 turns it will not equate to 420v, but if all the strands of the Litz was classed has a single turn then that will equate to 420v !.

I just don't get it .

Transformer outputs are:

Primary: 0: 0 – 240. V, P1,P2,P3
Secondary 1: 0 – 420. V @ 3 mA , S3
Secondary 2: 0 – 6. V @ 32 A , S1
Secondary 3: 0 – 12. V @ 400 mA, S2

Cheers
Spike
ps: think this might have been posted twice !

 

[Julie.]

?

What query?

 

[Spike1947]

?

What query?

 

[Spike1947]

Hi
The question is asking how can the transformer secondary winding output be 420v using a multi core (Litz) secondary winding with only175 turns , it will not equate to 420v, but if all the strands of the Litz was classed has a single turn then that will equate to 420v !. so does soldering the Litz at each end count has a single turn on the winding, if so how can it produce 420v volts, if they are classed has a single turn for each strand then that would !.

Spike

 

[Spike1947]

 

[Spike1947]

 

[Spike1947]

 

[Spike1947]

Last pic is with the Secondary 420v winding still on Trany

 

[Julie.]

Hi
The question is asking how can the transformer secondary winding output be 420v using a multi core (Litz) secondary winding with only175 turns , it will not equate to 420v, but if all the strands of the Litz was classed has a single turn then that will equate to 420v !. so does soldering the Litz at each end count has a single turn on the winding, if so how can it produce 420v volts, if they are classed has a single turn for each strand then that would !.

Spike

OK, the text is there now, when I asked all that was there was the photo attachment.

To work out how many turns are needed for the 420v you need to know how many are on the other windings.

So if the 240v winding has around 100 turns, then 175 would be correct etc.

 

[Avo Mk8]

Doesn't stack up to me (transformer lamination joke?)
You're thinking 9 x 175 = 1575 turns might theoretically give 425 volts (if the litz wire was all one long single strand?)
That means 0.27V per turn, so the primary has 888 turns?
(Your 175 turns of existing litz would give approx 47V)

If that's the primary on the right in the lathe, that might be more than 888 turns?
Do you know the volts per turn?

The spec you show says 3mA for the litz winding, but its capable of much more current than that.
And why litz? That's for high frequencies - skin effect conduction and all that, not for 50Hz transformers?
Perhaps Lucien can throw light on why litz might be used in a traditional mains transformer ?
I don't understand how you could get 425V from so few turns. Maybe someone has already modified it??

and final comment - nearly double the number of turns wiil be needed for the 425V winding than already there with the primary, (shown as on the same bobbin as the primary) so you might expect it to end up pretty full!

 

[Julie.]

Doesn't stack up to me (transformer lamination joke?)
You're thinking 9 x 175 = 1575 turns might theoretically give 425 volts (if the litz wire was all one long single strand?)
That means 0.27V per turn, so the primary has 888 turns?
(Your 175 turns of existing litz would give approx 47V)

If that's the primary on the right in the lathe, that might be more than 888 turns?
Do you know the volts per turn?

The spec you show says 3mA for the litz winding, but its capable of much more current than that.
And why litz? That's for high frequencies - skin effect conduction and all that, not for 50Hz transformers?
Perhaps Lucien can throw light on why litz might be used in a traditional mains transformer ?
I don't understand how you could get 425V from so few turns. Maybe someone has already modified it??

and final comment - nearly double the number of turns wiil be needed for the 425V winding than already there with the primary, (shown as on the same bobbin as the primary) so you might expect it to end up pretty full!

I am not sure it's litz for high frequency, it could also be for convenience.

The way to check is just wind 100t - then energise the primary - if there is 240v applied and you get 240 on this test winding, then you need 100t x 420/240 or 175t for 420v

If you get a different voltage - so 100v output for 230v input just recalculate accordingly.

 

[Avo Mk8]

I am not sure it's litz for high frequency, it could also be for convenience.

The way to check is just wind 100t - then energise the primary - if there is 240v applied and you get 240 on this test winding, then you need 100t x 420/240 or 175t for 420v

If you get a different voltage - so 100v output for 230v input just recalculate accordingly.

Agreed
Could even do it with say 10 turns if decent measuring instrument available.
Might be a faff putting the laminations back together, depending on type, but that experiment seems a vital next step.

 

[Julie.]

Unless you have the core cross section - assuming 1wb/m^2 flux density the volts per turn will be 1/4.44 × f x x-sectional area ( x flux density if not 1 weber per m^2)

Edit - changed to move to square metres for x-section.

 

[Spike1947]

Doesn't stack up to me (transformer lamination joke?)
You're thinking 9 x 175 = 1575 turns might theoretically give 425 volts (if the litz wire was all one long single strand?)
That means 0.27V per turn, so the primary has 888 turns?
(Your 175 turns of existing litz would give approx 47V)

If that's the primary on the right in the lathe, that might be more than 888 turns?
Do you know the volts per turn?

The spec you show says 3mA for the litz winding, but its capable of much more current than that.
And why litz? That's for high frequencies - skin effect conduction and all that, not for 50Hz transformers?
Perhaps Lucien can throw light on why litz might be used in a traditional mains transformer ?
I don't understand how you could get 425V from so few turns. Maybe someone has already modified it??

and final comment - nearly double the number of turns wiil be needed for the 425V winding than already there with the primary, (shown as on the same bobbin as the primary) so you might expect it to end up pretty full

I am not sure it's litz for high frequency, it could also be for convenience.

The way to check is just wind 100t - then energise the primary - if there is 240v applied and you get 240 on this test winding, then you need 100t x 420/240 or 175t for 420v

If you get a different voltage - so 100v output for 230v input just recalculate accordingly.

 

[Spike1947]

Hi
Thanks all for your replies , I just really want to know how can the spec say that the secondary winding I have to do has a 420v output, when the original winding had 175 turns of Litz wire ( 9x0.06mm dia ) each wire individualy laquered and soldered together at each terminal output lug .
I have spoken direct with the makers Trans Tronic ( UK) to confirm that .

I am not interested in the primary winding that is ok, but I had to remove the secondary winding ( Litz) to get at a thermal fuse that was under the first layer of the primary winding, have sorted that, now I need to replace this secondary winding, but am confused has to how it can give 420v !, maybe I am missing something here .

ps: The primary has roughly about 800 turns, 399 for the first layer !.
pps: Pic of PAT Tester board that the transformer feeds , it does a 500v DC test ! .

Spike