Isolation transformer usage

[Hyperion]

A Variac does not provide isolation.

Yes I know! - my response was because I hadn't realised the poster was proposing to use the saturation effect of an 'isolating transformer' to limit current. In failing to even consider this wild idea I thought to limit current he must mean 'Variac', and as I said "which makes a bit more sense"

 

[makaveli77]

I have an old Variac, I will power the variac from the isolation transformer , will go through the dut

 

[eiraved]

I find the Tenma isolation transformer very useful as basically it's a variac and isolation transformer combined in one unit.

 

[Refugee]

This is why I use an isolation transformer. All test gear is powered through regular grounded source while anything under test is powered through the isolation transformer. EEVBlog has a good video on it linked here:

Transformer:
Protection of your scope, and protection of yourself with hot chassis units. Both are achieved by using the transformer between the wall and the device under test.
Variac:
The Variac does not provide isolation as mentioned above. I usually use it to bring units up that have not been in use for a long time and are very old. This I do in hopes of reforming the old large capacitors.

 

[makaveli77]

I find the Tenma isolation transformer very useful as basically it's a variac and isolation transformer combined in one unit.

View attachment 3650324

Nice one, I have 2 units combined to do the same job

 

[eiraved]

I find the Tenma isolation transformer very useful as basically it's a variac and isolation transformer combined in one unit.

View attachment 3650324

Found this iso transformer a few years back at an engineer's estate sale. He left acreage of electrical equipment outside in the elements. This iso transformer was in his shed where he performed repairs on all sorts of electrical equipment. I would've loved to pick up his test equipment as it was all tubes but the folks running it were asking too much. They did let me rescue the tubes out of it for cheap though, which were all 6L6 tubes. Tested them and only one was bad out of the bunch.