Isolation transformer questions

[NwcNlgUfh2]

Hi
I'm trying to design a circuit to be hooked upto mains ac, and it was recommended that I should use an isolation transformer for safety purposes. 1) what purpose does this server, I know that it allows power to pass without the circuits being joined, but what affect does that have/why is it considered a safety feature. 2) what is the current draw on the input side, is it found by ohms law and using the impedance of the primary inductor (V/impedance=current) or how else?

 

[zoki85]

Hi
I'm trying to design a circuit to be hooked upto mains ac, and it was recommended that I should use an isolation transformer for safety purposes. 1) what purpose does this server, I know that it allows power to pass without the circuits being joined, but what affect does that have/why is it considered a safety feature. 2) what is the current draw on the input side, is it found by ohms law and using the impedance of the primary inductor (V/impedance=current) or how else?

Isolation transformer purpose is to galvanically isolate circuit (chassis, circuit load etc) from the power line conductor. Power line conductor is usually earthed and if person or any object directly touches it while being in contact with ground, the return path for current is provided. Note isolation transformers don't reduce danger IF the contact is made across their secondary winding. Normally they have 1:1 turns ratio and the current drawn is essentially equal to the secondary load current.