an air-tight metallic drum fixed at the top of the oil-tank

an air-tight metallic drum fixed at the bottom of the oil-tank

overload protection device

none of these

is a high voltage winding

is a low voltage winding

may be low or high voltage winding

the two types of windings are placed in a sandwich manner

sulpher

alkali

moisture

all the above

rating in kVA

efficiency

leakage reactance

per unit impedance

Megaohmmeter

Auto transformer

Variable transformer

Instrument transformer