Transformers

The core used in high frequency transformer is usually___________?

A. copper core
B. cost iron core
C. air core
D. mild steel core

In a transformer the resistance between its primary and secondary is____________?

A. zero
B. 1 ohm
C. 1000 ohms
D. infinite

Harmonics in transformer result in___________?

A. increased core losses
B. increased I2R losses
C. magnetic interference with communication circuits
D. all of the above

Helical coils can be used on___________?

A. low voltage side of high kVA transformers
B. high frequency transformers
C. high voltage side of small capacity transformers
D. high voltage side of high kVA rating transformers

The function of conservator in a transformer is___________________?

A. to project against’internal fault
B. to reduce copper as well as core losses
C. to cool the transformer oil
D. to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings

The thickness of laminations used in a transformer is usually____________?

A. 0.4 mm to 0.5 mm
B. 4 mm to 5 mm
C. 14 mm to 15 mm
D. 25 mm to 40 mm

Material used for construction of transformer core is usually___________________?

A. wood
B. copper
C. aluminium
D. silicon steel

Hysteresis loss in a transformer varies as CBmax = maximum flux density) ?

A. Bmax
B. Bmax1-6
C. Bmax1-83
D. B max

The noise resulting from vibrations of laminations set by magnetic forces, is termed as_________________?

A. magnetostrication
B. boo
C. hum
D. zoom

The transformer ratings are usually expressed in terms of______________?

A. volts
B. amperes
C. kW
D. kVA