Saturday, 8 September 2012

Some EE Questions

Q) For eleiminating 5th harmonics in a three phase AC system, the winding pitch should be?

Choices:   2/3, 4/5, 5/6, 6/5

Q) Magnetic circuit is saturated, delivering full load current at rated volt and current. n= constant, brushes at interpolar axis. When load is switched off, terminal voltage would?

Choices:  remain same , increase, decrease, will become 0.

Q) Under which of the following conditions dc motor with compensating winding is used?

A) Wide range of speed control above normal
B) Wide range of steady load variation with no speed control
C) Wide range of rapid variation in load

Q) What happens when field of DC shunt motor gets opened?

Q) Match?

Interpoles.................Commutation in D C machine.

Three pt. starter.........DC shunt motor

Dummy Coils............Wave Winding

Equaliser Ring...........Lap Winding

Q) The phase sequence of alternator will reverse when

a) If ( field current) is reversed, keeping direction of rotation same.
b) If remains same, direction of rotation is reversed.
c)If reversed, number of poles is doubled.
d) Number of poles doubled, If same.

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