MCQs Electrical Engineering 

1. A direct on-line starter is used for starting motors up to :
(1) 5 hp        
(2) 10 hp
(3) 20 hp        
(4) 40 hp                  
Ans  (1)
2. If single phasing occurs when the motor is running , if should not be loaded beyond............ percent of the rated load.
(1) 5         
(2) 25
(3) 50        
(4) 75.              
Ans  (3)
3. A motor starter is :
(1) fixed resistance
(2) variable resistance
(3) variable inductance
(4) variable capacitor
Ans  (2)
4. If a three -phase, 8 - pole, 50 Hz induction motor runs at a speed of 735 r.p.m. then the slip is :
(1) 0.02         
(2) 0.03
(3) 0.04          
(4) 0.05.               
Ans  (1)
5. The synchronous speed of a three phase induction motor having 20 polar and connected to a 50 Hz source is :
(1) 600 rpm      
(2) 1000 rpm
(3) 1200 rpm      
(4) 300 rmp            
Ans  (4)
6. When the rotor of a three phase induction motor is blocked, the slip is :
(1) 0.1         
(2) 0.5
(3) 1          
(4) 0.             
Ans  (3)
7. The slip of an induction motor under full load condition is about :
(1)।0.1         
(2) 0.03
(3) 0.2          
(4) 0.8.              
Ans  (2)
8. Which of the following is preferred r.p.m. for 4- pole induction motor ?
(1) 1485 r.p.m.        
(2) 1470 r.p.m.
(3) 1440 r.p.m.        
(4) 1320 r.p.m.            
Ans  (1)
9. A synchronous motor is found more economical over a load of :
(1) 2kW/
(2) 20kW
(3) 50kW
(4) 100kW
Ans  (4)
10. The ratio of starting torque to rinning torque in a synchronous motor is :
(1) Zero
(2) One
(3) Two
(4) Infinity
Ans  (1)
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