Balanced power / toroidal transformer

[Hammer]

Hi, I have a balanced power unit with a toroidal transformer. It was used overseas by a friend to step down the local 240v power to 120v so he can use US electronics in Asia.

 

he had since given the unit to me and I wonder if there is a way to rewire the transformer so that it does not step down the power so I can use it in the US.

 

the input leads on the transformer are black, red and orange. Currently, only black and red are used. Orange is unconnected.

 

the output is blue, red and yellow, with yellow tied to ground

 

 

i know it's not much to go on, but any thoughts? Since it's a balanced unit, if I used it as is with 240v input, the output is +60 and -60v.

 

Given the location of my system, it would be very costly for me to add a 240v outlet in that location.

 

thanks!

 

hammer

[esldude]

120 vac in the USA is not balanced. One leg is ground the other is +120 vac. Now 240 vac is ground, +120 vac and -120 vac. So I don't see how you will input single phase 120 vac and get out balanced 120 vac with only a transformer. Active electronics would be needed. Or as you have mentioned stepping down 240 vac to balanced 120 vac.

[robbbby]

120 vac in the USA is not balanced. One leg is ground the other is +120 vac. Now 240 vac is ground, +120 vac and -120 vac. So I don't see how you will input single phase 120 vac and get out balanced 120 vac with only a transformer. Active electronics would be needed. Or as you have mentioned stepping down 240 vac to balanced 120 vac.

 

You can absolutely get 120VAC balanced from a 120VAC input with the proper transformer. Each side becomes 60VAC instead of having 120VAC and a grounded conductor.

[Hammer]

You can absolutely get 120VAC balanced from a 120VAC input with the proper transformer. Each side becomes 60VAC instead of having 120VAC and a grounded conductor.

 

yes, and so my question is given the transformer is currently wired to step down from 240v to 120v balanced, is there a way to re-wire the input side of the transformer such that the output is 120v balanced?

 

i see that when i put the unit into a regular 120v outlet, my output is 60v balanced.

[robbbby]

What kind of balanced power unit/model?

 

Best bet would be to open it up and get the part number off the actual transformer.

[Hammer]

You can absolutely get 120VAC balanced from a 120VAC input with the proper transformer. Each side becomes 60VAC instead of having 120VAC and a grounded conductor.

 

yeah, I tried that, but the transformer is not labeled and neither is the unit itself...that's why i was hoping the wire colors in the OP might help/be enough to figure this out...

[One and a half]

By applying a varying voltage (with a small) variac on the primary in the combos of the red black and orange, it is possible then to measure the different tappings if any and work out how ot connect the unit to 120V instead of 240V.

 

It is also possible to measure the impedance and work out which winding is higher or lower. An instrument capable of F and variable V is beyond most hobbyists though, and the former method needs familiarity with electricity that can bite, hard.

 

For a novice, I would input the transformer with a small voltage, anything from 3Vac to 9Vac is fine, from a plug pack, and measure what the different colours are to each other. We could then work out which colour is what and how to get 60-0-60 out.

From there your electrician can wire the unit safely for use.

 

If it is a 60-0-60 output, it would need a GFCI and a raft of stickers, restrictions, et al to comply with the Nema codes if you live in that country.

[Hammer]

By applying a varying voltage (with a small) variac on the primary in the combos of the red black and orange, it is possible then to measure the different tappings if any and work out how ot connect the unit to 120V instead of 240V.

 

It is also possible to measure the impedance and work out which winding is higher or lower. An instrument capable of F and variable V is beyond most hobbyists though, and the former method needs familiarity with electricity that can bite, hard.

 

For a novice, I would input the transformer with a small voltage, anything from 3Vac to 9Vac is fine, from a plug pack, and measure what the different colours are to each other. We could then work out which colour is what and how to get 60-0-60 out.

From there your electrician can wire the unit safely for use.

 

If it is a 60-0-60 output, it would need a GFCI and a raft of stickers, restrictions, et al to comply with the Nema codes if you live in that country.

 

Thanks for the suggestion. What can I use that will generate the 3vac to 9vac so I can test?

[Harpy]

Thanks for the suggestion. What can I use that will generate the 3vac to 9vac so I can test?

 

3A Variac 0~130 VAC | 120-840

[sandyk]

One and a half's suggestion is to use an AC plugpack . 9V AC and even 12V AC types should be readily available.

As you don't have adequate DIY experience, I believe that One and a half's suggestions would be mainly aimed at helping you avoid coming to grief with dangerous AC voltages.

[Superdad]

If I had that transformer I would wire a wall outlet for 240V and plug it into that.

 

When I built my room I ran both legs to every box. That way I could both choose the better sounding 120V leg (it DOES make a difference), or wire in some 240V outlets and reconfigure my gear for 240V (which often sounds better).

 

[One and a half]

If I had that transformer I would wire a wall outlet for 240V and plug it into that.

 

When I built my room I ran both legs to every box. That way I could both choose the better sounding 120V leg (it DOES make a difference), or wire in some 240V outlets and reconfigure my gear for 240V (which often sounds better).

 

[ATTACH=CONFIG]11784[/ATTACH]

 

OMG, used to see that in industrial complexes, in a home not so often! 00awg is great, not much of a voltage drop with that one. The OP did say, he couldn't wire in a 240V line.

 

Thankfully 240V draws half the current, means less wire size and less harmonics. It is also interesting to note that SPL uses 120V rails in their HP amps, very simply to provide a high slew rate, if you have 120V instead of 30V, your slew rate (and responses) are 1/4 the time Nothing to do with the subject though, sorry.

[One and a half]

3A Variac 0~130 VAC | 120-840

 

That's a great price!

[One and a half]

Thanks for the suggestion. What can I use that will generate the 3vac to 9vac so I can test?

 

Chop the ends off this device and wire straight on to the transformer. You need a voltmeter (DMM) to measure.

Connect any one leads of the plugpack to say the red, the other end of the plug pack to the black. Measure Orange to black, and orange to red. Measure red to black.

 

Shut off, and attach the plug pack to the red and orange and measure to the black.

Measure the outputs and see what you get.

 

 

Amazon Link

[Hammer]

I get it now...Thank you all for the tips!

 

Out of curiosity, besides using this for it's original intended purpose which was the ability to connect US equipment in Asia, is there any sonic benefit to ACTUALLY installing a new 240v 20 amp outlet so that I can use the transformer to stepdown to 120v without any modification?

[Skip Pack]

Yes, I suspect in, most cases. You get balanced power with a good dose of common-mode noise rejection further back up the power chain back to your panel and possibly further back. I've done this several times and have always noticed a modest gain every time.

 

Skip

 

 

I get it now...Thank you all for the tips!

 

Out of curiosity, besides using this for it's original intended purpose which was the ability to connect US equipment in Asia, is there any sonic benefit to ACTUALLY installing a new 240v 20 amp outlet so that I can use the transformer to stepdown to 120v without any modification?

[vedat]

I get it now...Thank you all for the tips!

 

Out of curiosity, besides using this for it's original intended purpose which was the ability to connect US equipment in Asia, is there any sonic benefit to ACTUALLY installing a new 240v 20 amp outlet so that I can use the transformer to stepdown to 120v without any modification?

 

 

I don’t think so it is possible to get the 120v balanced output from this transformer by rewiring as we cannot change the turns ratio of transformer as it is step down transformer. So, I believe you should use the different transformer with turn ratio 1:1 to get the 120v balanced output from 120Vac input.