AP ECET EEE 2017-2

1. In a machine, for the same number of slots and same current in armature conductor, which of the following will induce higher emf

A. lap winding
B. wave winding
C. compensating winding
D. pole winding

Answer : wave winding
Explain:-

2. A series motor drawing an armature current of Ia is operating under saturated magnetic conditions. The torque developed in the motor is proportional to

A. 1/Ia
B. (1/Ia)^2
C. Ia^2
D. Ia

Answer : Ia
Explain:-

3. When is the mechanical power developed by DC motor is maximum

A. back emf is equal to applied voltage
B. back emf is equal to zero
C. back emf is equal to half the applied voltage
D. back emf is square the applied voltage

Answer : back emf is equal to half the applied voltage
Explain:-

4. Which of the following are the variable losses in rotating machine

A. core loss and mechanical loss
B. core loss and stray load loss
C. copper loss and core loss
D. copper loss and stray load loss

Answer : copper loss and stray load loss
Explain:-

5. The speed of the DC motor is related to the back emf and flux in the following ways

A. directly proportional to flux and inversely proportional to back emf
B. directly proportional to back emf and inversely proportional to flux
C. inversely proportional to flux and inversely proportional to back emf
D. directly proportional to flux and directly proportional to back emf

Answer : directly proportional to back emf and inversely proportional to flux
Explain:-

6. For controlling the vibration of the disc AC energy meter, the damping torque is produced by

A. Eddy current
B. chemical effect
C. electrostatic effect
D. magnetic effect

Answer : Eddy current
Explain:-

7. Which of the following bridges will be used for measurement of low resistance

A. Kelvin bridge
B. Maxwell's bridge
C. wheatstone bridge
D. Hays bridge

Answer : Kelvin bridge
Explain:-

8. The current transformer has a phase error of +3° . The phase angle between primary and secondary currents is

A. 3°
B. 177°
C. 180°
D. 183°

Answer : 177°
Explain:-

9. If one of the control springs of a permanent magnet moving coil ammeter is broken then, when connected it will read

A. zero
B. half of the correct value
C. twice the correct value
D. an infinite value

Answer : zero
Explain:-

10. A circuit comprises a coil of resistance R and inductance L, in parallel with an ideal Capacitor C. At the resonant frequency, the impedance of parallel combination is

A. R
B. (LC)/R
C. L/(RC)
D. infinity

Answer : L/(RC)
Explain:-