Electronics > Beginners

UPS as an isolation transformer?

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-DOM-:
Hi Guys,

I have done a bit of research although thought i would check other peoples opinions on using a UPS as an isolation transformer. I realise that not  all use an isolation transformer in the design however if i found one that did would i be ok to use? I have studied power supplies so am not a complete noob but only just starting to do some repairs on them at home.

Any help would be great thanks Damien :)

Rerouter:
a ups is not an isolation transfomer unless you unplug it from the wall, even the active types that charge up the battery and then directly invert off the battery tend to share a common ground,

-DOM-:
Cheers for that, i didnt realise they shared the ground.

Rules out that idea. May look into DIY

ConKbot:

--- Quote from: -DOM- on March 14, 2013, 10:18:13 am ---Cheers for that, i didnt realise they shared the ground.

Rules out that idea. May look into DIY

--- End quote ---
Its pretty much a cardinal sin for any device with an outlet on it to not have the ground connected though.  I cant think of any consumer application where it would be safe/appropriate enough for the device to be sold readily. 


However, depending on the UPS type, you may find a useable transformer.   I remember a 300VA ups I had used a center tapped winding to step the 12v up to 120v, right at 60hz.  throw 2 of them back to back and you'd have your isolation transformer.

However some use a high frequency SMPS to step 12/24v upto rectified mains voltage, and then a class D amplifier to output the 60hz from the high voltage rail.  Not so useable in your application.

ptricks:
You could operate a UPS unplugged from the AC source for isolation but you would need a UPS that could run a long time off battery which would cost more than an isolation transformer.

Depending on what current output you need it is better to look for old stereo amplifiers that contain transformers, easy to tell by the weight. Old amplifier transformers are good for several amps.

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