What is the primary use of Isolation Transformers

 

If you want to get a power from the city power as AC220V, AC120V, AC110V, for safety reason so you have to use a Isolation Transformer to get the power.

if you connecting the power directly from the city power, sometime it will happend some unpredictable things.

One Transformer.
Vin 220Vac → 220Vac To 220Vac
Vin 120Vac → 120Vac To 120Vac
Vin 110Vac → 110Vac To 110Vac

Two Transformers.
Vin 220Vac → 220Vac To 110Vac, 110V To 220Vac
Vin 220Vac → 220Vac To 48Vac, 48V To 220Vac
Vin 110Vac → 110Vac To 48Vac, 48V To 110Vac
Vin 110Vac → 110Vac To 24Vac, 24V To 110Vac

 

In a word to "isolate".

 

Isolation transformers remove the earth ground reference from the power going to the device connected to the load side. A chassis ground safety line usually carried through and can cause problems to the un-initiated.

They do for power what an optical isolator does for signals.

 

I use one for safety and so I can connect my scope to live four reference.