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Isolation Transformers

I bought an isolation transformer from a fellow selling his home audio gear about a year or so ago. It’s a 12” cube that weighs roughly 60 lbs and has 8 plugs in the back. It was apparently used in a hospital. 
I have most of my gear including a tube preamp plugged into it mostly for protection purposes. It puts out a constant 124v which is a few more than what I get directly from the wall socket.
Anyone else using this sort of device as a “power conditioner” and what are the pros and cons of using one? I’m guessing delivering a constant voltage (almost) regardless of the load is the main advantage of this type of device but am wondering if it impedes full current delivery at high amplifier loads. Thanks. 
128x128kalali
erik_squires
16,021 posts
 
Hi Kalali,

I'm not sure what you have. Can you post the make and model?

An isolation transformer by itself does not regulate voltage. It does eliminate DC and prevent certain types of shock, as well reduce noise due to the inductance. 

A voltage regulator may also be present, but these can be with or without the isolation component. The benefit here is, of course, a tightly regulated AC voltage, though not necessarily surge protection, and it may take a little for the regulator to adjust to incoming and outgoing conditions. 

Best,


E
oicu812's avatar
oicu812
110 posts
 
Isolation transformers have many uses. Google is your friend, punch in what model you ended up with and it's specs. Start with the link below for an explanation to the basics:
http://www.shure.com/americas/support/find-an-answer/transformers-when-to-use-and-how-does-it-work
jea48
4,407 posts
 
It was apparently used in a hospital.
What is the Kva rating? It will say on the data plate.

Does it say ’Medical Grade’ anywhere on it?

If yes:
Most medical grade isolation transformer I have ran across float the secondary winding above ground. That means both AC Line contacts on the receptacle outlets are fed from Hot ungrounded legs, conductors. Neither of the two hot conductors have a reference to ground. Therein, not to the metal case/enclosure of the transformer or to the ground contact of the receptacle outlets.

I would suggest you use a volt meter and measure for voltage from both contacts to the equipment ground contact on the outlets.


If the isolation transformer is wired as a Grounded Power System:
Short slot of the outlet to equipment ground should measure 120VAC nominal. (You said it runs 124Vac.)Longer slot of the two, or ’T’ slot, the neutral contact should measure a solid zero volts to ground.

If the isolation transformer was left ungrounded then you have an Isolated Power System. Any voltage readings from either contact to ground will be phantom voltage. Usually a digital meter reading will be all over the place and will not hold steady.

Medical grade transformers are meant to be used by qualified personnel only.
If your transformer floats the secondary above ground you should have an electrician wire it as a grounded power system. It’s simple do.

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