Dual Primary Wiring - Power Transformer

[GussyLoveridge]

Hi folks - thanks again for the help in advance. I really do appreciate you helping me through these things from time to time.

I have purchased a Pri: 2 x 115V Sec: 240V, 50V 2 x 12V transformer from Don Audio. I'm in Canada, 120ish VAC, 60 Hz.

I am slightly confused about the dual primary wiring, perhaps I should have sorted this out before purchasing it. No doubt. Like most things in life, I am stumbling into it.

Do I just hook up 1 set of the primary wires and leave the others unused?

I assume that I would need to hook up both sets in series for 240V use.

Do I hook them up in parallel? Is there a need to be mindful of phasing? (surely?)

 

[scott2000]

Do I hook them up in parallel? Is there a need to be mindful of phasing? (surely?)

Yes for 115.....

 

[GussyLoveridge]

The colours are listed on the unit as 115: yellow/white 115: orange/purple - would it be safe to assume that yellow and orange should be tied together and white and purple? Does anyone have experience using this transformer in this fashion?

 

[ruffrecords]

Yes, you definitely wire them in parallel.

Cheers

ian

 

[ccaudle]

would it be safe to assume that yellow and orange should be tied together and white and purple?

Don't assume anything, go look up the data on the transformer you bought. There will be documentation somewhere which explicitly notes which wires should be connected together for parallel operation.

 

[GussyLoveridge]

That's the thing - I didn't receive any information with the transformer when I bought it from Don Audio. I kind of figured there would be a sheet in the box. I have reviewed their website looking for a pdf or something but can't seem to find it. I wrote on their standard webform email a couple days ago. I'm just noticing now a tech @ don-audio dot com email on the unit. I'm going to give that a whirl and see how it goes.

EDIT: Just put a hyphen in the email address for don audio.

 

[ccaudle]

I didn't receive any information with the transformer when I bought it from Don Audio

Which model? I looked at one model on the website and it had connection information on the product page. I didn't go look at every model, didn't seem a good use of time since I don't know which specific part you have.

 

[GussyLoveridge]

This is the one: Audio Toroidal Transformer - Pri.: 2x115v- Sec.: 240V, 50V, 2 x 12V,

 

[Evertide]

This is the one: Audio Toroidal Transformer - Pri.: 2x115v- Sec.: 240V, 50V, 2 x 12V,

Put 12 Volt ac on the green 12 Volt , measure 115 on yellow - white
Hook up yellow and orange , measure 115 on white and purple ( maybe out of phase ) measure zero between white and purple in phase or 230 out of phase...

 

[GussyLoveridge]

Thanks - that I can do. I appreciate the help very much.

 

[JohnRoberts]

I am tempted to suggest just hooking it up and seeing what you get.

BUT I am reminded of one time back in the 70s when I told a junior technician working for me when he asked a similar question. I told him to just hook it up and see what happens. He wired in a power transformer backwards and blew up several components from over voltage. We both learned a little something that day.

 

[GussyLoveridge]

Put 12 Volt ac on the green 12 Volt , measure 115 on yellow - white

Yes.

Hook up yellow and orange (tied together)

Measured 0V on white & purple

Swapped orange with purple (Now yellow and purple are tied together)

Measured 230 V between white and orange.

So: Yellow and Purple are out of phase.

For parallel 115 V input. I will tie white and purple together and yellow and orange together.

 

[GussyLoveridge]

Can anyone speak to why you would power the 12V end to do all this?

Could you not rig the primaries up somewhat willy-nilly and push in 115V and just measure a known secondary until you get it right? I mean you can be certain that you're not going to be tying together primary leads from the same coil together right based on the known information?

Can you mess the thing up that way?

EDITED FOR CLARITY.

 

[Admiral-dk]

Can you mess the thing up that way?

Oh YES you CAN ...!!!!

Both in Serial and in Parrallel you WILL get a Short-Circuit if the two Primaries are not wirred in Phase !!!! => BANG !!!! -> Smoke.
(actually not totally correct to say it is a short - but the Primary will draw a much Current as it can, and that is a LOT more than in normal working condition).

I have used both a low AC from another transformer and from a Tone-Gen to those tests on all kind of transformers and that is a safe way to do so. I have also in some cases 'Just wirred it up and tested' - BUT ALWAYS using a VARIAC and Always starting @ Zero Volts + Keeping Eyes Both on the Amp- & Volt- Meter on the Variac, while turning Very slowly up.

Per