Electrical Machines(Electrical Engineering Questions ) Questions and Answers

Question 1. Iron losses are considered to be the constant losses. It depends on
  1.    Voltage
  2.    Frequency
  3.    Both (a) and (b)
  4.    None of these
Explanation:-
Answer: Option C. -> Both (a) and (b)
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 2. Copper losses in a rotating machine are
  1.    Variable losses
  2.    Constant losses
  3.    Both (a) or (b)
  4.    None of these
Explanation:-
Answer: Option A. -> Variable losses
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 3. Stray losses are the losses which vary with the load but their relationship with load current cannot be identified. Stay losses is maximum in
  1.    Synchronous machines
  2.    D.C. machines
  3.    Induction machines
  4.    Equal in all types of machines
Explanation:-
Answer: Option B. -> D.C. machines
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 4. The brush contact losses in a d.c. Machine is
  1.    Inversely proportional to the square of current
  2.    Directly proportional to the square of current
  3.    Inversely proportional to the current
  4.    Directly proportional to the current
Explanation:-
Answer: Option D. -> Directly proportional to the current
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 5. Electrical power output in a d.c. generator is equal to
  1.    Electrical power developed in armature – copper losses
  2.    Mechanical power input – iron and friction losses
  3.    Electrical power developed in armature – iron and copper losses
  4.    Mechanical power input – iron and friction losses – copper losses
Explanation:-
Answer: Option D. -> Mechanical power input – iron and friction losses – copper losses
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 6. Out of electrical, mechanical and magnetic losses, the losses which is minimum is
  1.    All are equal
  2.    Electrical losses
  3.    Magnetic losses
  4.    Mechanical losses
Explanation:-
Answer: Option D. -> Mechanical losses
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 7. Mechanical power developed in armature of a d.c. motor is given by
  1.    Electrical power input to motor – copper losses
  2.    Motor output + iron and friction losses
  3.    Both (a) & (b)
  4.    None of these
Explanation:-
Answer: Option C. -> Both (a) & (b)
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 8. A 120 V shunt generator running at 850 rpm has its armature and shunt field resistance of 0.15 ohm and 50 ohm respectively. It supplies 200 lamps each rated at 60 W, 100 V. The friction and windage and core loss of the machine is 400 W. its armature copper loss on full load and shunt field loss is
  1.    2156.7 W, 200 W
  2.    2232.6 W, 200 W
  3.    2156.7 W, 240 W
  4.    2232.6 W, 240 W
Explanation:-
Answer: Option B. -> 2232.6 W, 200 W
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 9. A d.c. shunt generator delivers 190 A at a terminal voltage of 220 V. The copper losses and stray losses are 2000 W and 1000 W respectively. The efficiency of the generator is
  1.    91.35 %
  2.    92.60 %
  3.    93.30 %
  4.    94.23 %
Explanation:-
Answer: Option C. -> 93.30 %
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 10. The hysteresis motor are mainly used in tape recorders because
  1.    Of its extremely steady torque
  2.    Constant speed
  3.    Reduced initial current
  4.    None of these
Explanation:-
Answer: Option A. -> Of its extremely steady torque
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
© Lakshya_Education.com, All Right Reserved.
Contact Us services