N atural air coo ling is generally restricted for transformers up to__________?

The no-load current drawn by transformer is usually what per cent of the full-load current ?

A. 0.2 to 0.5 per cent
B. 2 to 5 per cent
C. 12 to 15 per cent
D. 20 to 30 per cent

Minimum voltage regulation occurs when the power factor of the load is_____________?

A. unity
B. lagging
C. leading
D. zero

The transformer oil should have _______ volatility and _______ viscosity?

A. low,low
B. high,high
C. low,high
D. high,low

A no-load test is performed on a transformer to determine_______________?

A. core loss
B. copper loss
C. efficiency
D. magnetising current
E. magnetising current and loss

During open circuit test of a transformer:

A. primary is supplied rated voltage
B. primary is supplied full-load current
C. primary is supplied current at reduced voltage
D. primary is supplied rated kVA

The dielectric strength of transformer oil is expected to be______________?

A. lkV
B. 33 kV
C. 100 kV
D. 330 kV