Quiz: Electrical Engineering
Exam: UPSSSC JE
Topic: Miscellaneous
Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute
Q1. The advantage of putting tapping at the phase ends of a Transformer is
(a) to obtain fine variation of voltage
(b) to operate with ease
(c) to reduce the no of bushing
(d) to obtain better regulation
Q2. The field of self-excited generator is excited by
(a) AC
(b) DC
(c) by its own current
(d) Either AC or DC
Q3. The main use of DC shunt motor for driving the
(a) train
(b) crane
(c) hoist
(d) machine tools
Q4. In DC shunt motors, as load is reduced then the speed will be
(a) increase abruptly
(b) increase in proportion to reduction in load
(c) remain almost constant
(d) reduce
Q5. The variable resister shunting the field of DC series motor is called
(a) Armature diverter
(b) voltage regulator
(c) potential diverter
(d) field diverter
Q6. A DC series motor is accidently connected to single phase ac supply. The torque produce will be
(a) of zero average value
(b) Oscillating
(c) steady and unidirectional
(d) pulsating and unidirectional
Q7. In case of DC series motor, it is possible to have finite no-load speed if a resistance is connected across its-
(a) Field terminals
(b) Armature terminals
(c) Field and armature together
(d) It is not possible
Q8. The current drawn by a 120 V DC motor of armature resistance 0.8 Ω and back emf 110 V is
(a) 12.5 A
(b) 24.5 A
(c) 22.4 A
(d) 10.5 A
Q9. If the variable losses in a DC motor is 500 W. then for maximum efficiency of the motor, the constant losses must be
(a) 250 W
(b) 450 W
(c) 650 W
(d) 500 W
Q10. Ward-Leonard system of speed control is NOT recommended for:
(a) frequent motor reversals
(b) very low speeds
(c) constant speed operation
(d) wide speed range
Solutions
S1. Ans. (c)
Sol. to reduce the no of bushing
S2. Ans. (c)
Sol. The field of self-excited generator is excited by its own current.
S3. Ans. (d)
Sol. The main use of DC shunt motor is driving machine tools.
S4. Ans. (c)
Sol. In DC shunt motors, as load is reduced then the speed will be remaining almost constant.
S5. Ans. (d)
Sol. Field diverter
S6. Ans. (d)
Sol. pulsating and unidirectional
S7. Ans. (b)
Sol. Armature terminals
S8. Ans. (a)
Sol. We have relation in case of DC motor as V=E_b+I_a R_a
I_a=(V-E_b)/R_a = (120-110)/0.8=12.5 A
S9. Ans. (d)
Sol. According to the condition of DC motor maximum efficiency, Variable losses = Constant losses
S10. Ans. (c)
Sol. constant speed operation
