Question

How can the meter circuit be isolated from the power circuit?

(a) by grounding

(b) through electrical isolation

(c) by physical separation

(d) through mechanical isolation

I had been asked this question during an interview for a job.

This key question is from Advantages of Instrument Transformers in section Extension of Instrument Ranges of Electrical Measurements

Answer 1

Right option is (b) through electrical isolation

Easy explanation: Leads of the secondary winding transformer are brought to the switch board thus separating them from high voltage windings. In this way, the meter circuit is isolated from the high voltage power circuit.