Electrical Transformer Multiple choice Question (Electrical Mcqs) and Answer Part 1

      

                         Electrical Engineering Objective Question and Answer 

     
Electrical Transformer MCQs with Answers  

1-which of the following is minimized by laminating the core of transformer?

       (A)   Hysteresis Loss 
       (B) Heat loss 
       (C) eddy current loss 
       (D) All of the above

Answer: (C)

 2-The function of breather in transformer is? 

      (A)   To provide oxygen to the cooling oil 
      (B) To provide cooling air 
      (C) To arrest the moisture of transformer when outside air enter the transformer 
      (D) To filter the transformer oil

Answer: (C) 

 3-Iron loss in a transformer occurs in?

       (A)   Core 
       (B) Winding  
       (C) Main body  
       (D) insulating oil

Answer: (A)

 4-Under No load condition which of the loss is negligible?

       (A)   Hysteresis loss 
       (B) Eddy current loss 
       (C) Copper loss 
       (D) All losses  have the same magnitude

Answer: (C)

 5- Open Circuit test of transformer gives?

      

       (A)   Hysteresis loss  
       (B) Eddy current loss 
       (C) Sum of hysteresis loss and eddy current loss  
       (D) copper loss

Answer: (C)

6-Copper loss in transformer occurs in?

     

       (A)   Core  
       (B) Winding  
       (C) main body  
       (D) bushings

Answer: (B)

7-which test on transformer provides information about regulation, efficiency and heading under load conditions?

      

       (A)   Open circuit test 
       (B) Back to best test 
       (C) Hopkinson test  
       (D) Short circuit test  

Answer: (C)

8-For a transformer the condition for maximum efficiency is?

      

     (A)   Hysteresis loss=eddy current loss 
     (B) core loss = hysteresis loss 
     (C) copper loss=iron loss   
     (D) total loss =2/3 *copper loss

Answer: (C)

9-Eddy current losses in a transformer core can be reduced by?

     

       (A)   Reducing the thickness of lamination  
       (B) increasing the thickness of laminations  
       (C) increasing the air gap in the magnetic circuit  
       (D) reducing the air gap in the magnetic circuit 

Answer: (A)

10- When Rs is the resistance of the secondary winding of the transformer and k is the transformation ratio, the secondary resistance as referred to primary side is given by?

      

       (A)   kR  
       (C) Rs/k 
       (D) Rs/

Answer: (D)

11-in a transformer the magnetic coupling between the primary and secondary circuit can be increased by?

     

      (A)   Increasing the number of turns 
      (B) using soft material for winding 
      (C) using the magnetic core of low reluctance 
      (D) using transformer of better quality    

Answer: (C)

  12-if flux density in the core of transformer is increased?

         

       (A)   Frequency on the secondary winding will be changed 
       (B) wave shape on secondary side will be  distorted 
       (C) size of the transformer can e reduced 
       (D) eddy current losses will reduce

Answer: (C)

13- Which loss in a transformer varies significantly with load?

      

      (A)   Hysteresis loss 
      (B) eddy current loss  
      (C) copper loss  
      (D) core loss

Answer: (C)

14-Assume the voltage constant, if frequency is increased then?

     

      (A)   Eddy current losses will decrease 
      (B) hysteresis losses will decrease  
      (C) eddy current losses will remain unchanged  
      (D) hysteresis losses will remain unchanged   

Answer: (C)

 15-The power factor in a transformer

       

      (A)   Is always unity  
      (B) is always leading  
      (C) is always lagging 
      (D) depends on the power factor of load

Answer: (D)

16-At no load the current taken by a transformer

       

       (A)   Lags behind the applied voltage by 80⁰ 
       (B) lags behind the applied voltage by 50⁰ 
       (C)   leads the applied voltage by 50⁰  
       (D) leads the applied voltage by 80⁰

Answer: (A)

17-The efficiency of a transformer does not depend on

      (A)   Current 
      (B) load   
      (C) power factor 
      (D)all of the above

Answer: (C)

18- If the secondary of 1:10 step up transformer is connected to the primary of 1:5 steps up transformer, the transformation ratio will be

      

       (A)   15 
       (B) 30 
       (C) 50 
       (D) 2500

Answer: (C)

19-Which of the following transformer will be smallest in size  

  

      (A)   10 kVA,50 Hz 
      (B) 10 kVA,60 Hz   
      (C) 10 kVA,100 Hz   
      (D) 10 kVA,200 Hz

Answer: (A)

20-A 1600 kVA, 200 Hz transformer is operated at 50 Hz. Its kVA rating should be restricted to

       ( A)   800 kVA
       (B) 400 kVA  
       (C) 200 kVA 
       (D) 100 kVA

Answer: (B)