1% to 2%
2% to 5%
5% to 12%
12% to 20%%
cooling and lubrication
insulation and lubrication
insulation and cooling
insulation, cooling and lubrication
To work as a control transformer
To work as a variable transformer
To work as a distribution transformer
To work as an isolating transformer
increase output power
increase output voltage
increase output current
none of these
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