A shaded pole motor can be used for
A. toys
B. hair dryers
C. circulators
D. any of the above
Select an option to see the answer and solution.
Hysteresis motor is particularly useful for high-quality record players and tape-recorders because
A. it revolves synchronously
B. it is not subject to any magnetic or mechanical vibrations
C. it can be easily manufactured in extremely small sizes of up to 1 W output
D. it develops hysteresis torque which is extremely steady both in amplitude and phase
Select an option to see the answer and solution.
The speed/load characteristics of a universal motor is same as that of
A. D.C. motor
B. D.C. shunt motor
C. D.C. series motor
D. none of the above
Select an option to see the answer and solution.
If the capacitor of a single-phase motor is short-circuited
A. the motor will not start
B. the motor will run
C. the motor will run in reverse direction
D. the motor will run in the same direction at reduced r.p.m.
Select an option to see the answer and solution.
The repulsion start induction run motor is used because of
A. good power factor
B. high efficiency
C. minimum cost
D. high starting torque
Select an option to see the answer and solution.
In split phase motor main winding is of
A. thin wire placed at the top of the slots
B. thin wire placed at the bottom of the slots
C. thick wire placed at the bottom of the slots
D. thick wire placed at the top of the? slots
Select an option to see the answer and solution.
Most of the fractional horsepower motors have either
A. hard and annealed bearings
B. ball or roller bearings
C. soft and porous bearings
D. plain or sleeve bearings
Select an option to see the answer and solution.
The motor used for the compressors is
A. d.c. series motor
B. shaded pole motor
C. capacitor-start capacitor-run motor
D. reluctance motor
Select an option to see the answer and solution.
If a particular application needs high speed and high starting torque, then which of the following motor will bepreferred ?
A. Universal motor
B. Shaded pole type motor
C. Capacitor start motor
D. Capacitor start and run motor
Select an option to see the answer and solution.
If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then
A. motor will not come up to speed
B. motor will not carry the load
C. current drawn by the motor will be excessively high
D. electrolytic capacitor will, in all probability, suffer break down
Select an option to see the answer and solution.
A universal motor can run on
A. D.C. only
B. A.C. only
C. either A.C. or D.C.
D. none of the above
Select an option to see the answer and solution.
Locked rotor current of a shaded pole motor is
A. equal to full load current
B. less than full load current
C. slightly more than full load current
D. several times the full load current
Select an option to see the answer and solution.
The rotor of a hysteresis motor is made of
A. aluminium
B. cast iron
C. chrome steel
D. copper
Select an option to see the answer and solution.
In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will
A. Become unstable
B. Draw excessive armature current and may burn out
C. Fall out of synchronism and come to stand still
D. Run as induction motor
Select an option to see the answer and solution.
Which of the following motor will give the highest starting torque ?
A. D.C. shunt motor
B. Schrage motor
C. Repulsion start and induction run motor
D. Universal motor
Select an option to see the answer and solution.
Which of the following motors has highest starting torque ?
A. Repulsion motor
B. Shaped pole motor
C. Capacitor-start motor
D. Split-phase motor
Select an option to see the answer and solution.
A capacitor-start single phase induction motor is switched on to supply with its capa-citor replaced by an inductor of equivalent reactance value. It will
A. start and then stop
B. start and run slowly
C. start and run at rated speed
D. not start at all
Select an option to see the answer and solution.
If starting winding of a single-phase induction motor is left in the circuit, it will
A. run faster
B. spark at light loads
C. draw excessive current and overheat
D. run slower
Select an option to see the answer and solution.
The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it
A. improves the efficiency
B. helps the rotor teeth to remain under the stator teeth
C. helps in reducing the tendency of the rotor teeth to remain under the stator teeth
D. improves the power factor
Select an option to see the answer and solution.
In case of a shaded pole motor the direction of rotation of the motor is
A. from main pole to shaded pole
B. from shaded pole to main pole
C. either of the above depending on voltage
D. either of the above depending on power factor
Select an option to see the answer and solution.