Electrical Machines - Single Phase Motors
1. The starting winding of a single-phase motor is placed in the
2. One of the characteristics of a single- phase motor is that it
(a) is self-starting
(b) is not self-starting
(c) requires only one winding
(d) can rotate in one direction only.
3. After the starting winding of a single- phase induction motor is disconnected from supply,
it continues to run only on ⸺ winding.
4. If starting winding of a single-phase induction motor is left in the circuit, it will
(a) draw excessive current and overheat
(b) run slower
(c) run faster
(d) spark at light loads.
5. The direction of rotation of a single-phase motor can be reversed by
(a) reversing connections of both windings
(b) reversing connections of starting winding
(c) using a reversing switch
(d) reversing supply connections.
6. If a single-phase induction motor runs slower than normal, the more likely defect is
(a) improper fuses
(b) shorted running winding
(c) open starting winding
(d) worn bearings.
7. The capacitor in a capacitor-start induction- run ac motor is connected in series with ......
8. A permanent-split single-phase capacitor motor does not have
(a) centrifugal switch
(b) starting winding
(c) squirrel-cage rotor
(d) high power factor.
9. The starting torque of a capacitor-start induction-run motor is directly related to the
angle α between its two winding currents by the relation
(a) cos α
(b) sin α
(c) tan α
(d) sin α/2.
10. In a two-value capacitor motor, the capacitor used for running purposes is a/an
(a) dry-type ac electrolytic capacitor
(b) paper-spaced oil-filled type
(d) ceramic type.
1.b 2. b 3. d 4. a 5. b
6.d 7. a 8. a 9. b 10. b