Electrical Transformer Multiple choice Question (Electrical Mcqs) and Answer Part 3

                  Electrical Engineering Objective Question and Answer 

                                                            

                                                                Electrical Transformer MCQs with Answers

 41- A transformer will have the highest efficiency near 

       

    (A)   25% of rated load  

    (B) 50% of rated load  

    (C) 75% of rated load  

    (D) 93% of rated load

Answer: (D)

  42- A 1kVA transformer at full load will have? 

     (A)   Copper losses greater than iron losses 

     (B) iron losses greater than copper losses  

     (C) windage more than iron losses  

      (D) windage losses less than copper losses

Answer: (A)

  43- The Sum of all losses in a 1kVA transformer, at full load will be of the order of? 

        (A)   10 W 

        (B) 50 W  

        (C) 150 W   

        (D) 250 W

Answer: (B)

  44- In a transformer the hysteresis losses are 100K when the input voltage form factor is 2.11 if the input form factor voltage is 1.40, the hysteresis losses will be

        (A)   140 K 

        (B) 140/111 K  

        (C) 200 K  

        (D) 70 K

Answer: (D)

  45- The phase difference between the primary and secondary voltage of a transformer is? 

        (A)   0⁰ 

        (B) 90⁰ 

        (C) 180⁰   

        (D) between 30⁰ and 60⁰

Answer: (C)

  46- In transformer if peak voltage is fed to the primary? 

        

        (A)   The iron losses will be less 

        (B) the iron losses will be more 

        (C) the copper losses will be less   (D) the windage losses will be more

Answer: (A)

47- In a transformer the copper losses at half load as compared to that at full load will be? 

      

      (A)   4 times 

      (B) 2 times  

      (C) half   

      (D) 1/4

Answer: (D)

  48- The path of magnetic flux in transformer should have? 

       

      (A)   Low reluctance  

      (B) low resistance   

      (C) high reluctance  

      (D) high resistance

Answer: (C)

  49- The desirable properties of transformer core material are 

      (A)   Low permeability and low hysteresis loss 

      (B) high permeability and high hysteresis loss   

      (C) high permeability and low hysteresis loss  

      (D) low permeability and high hysteresis loss 

Answer: (C)

  50- Core losses in transformer are  

      (A)   Vary from 1%  to 3%  between no load and full load 

      (B) vary from 10%  to 50% between no load and full load 

      (C) decrease as load on the transformer increases 

      (D) depends only on the supply voltage

Answer: (A)

   51- The function of transformer oil in transformer is  

     

      (A)   To provide insulation and cooling  

      (B) to provide protection against lightning  

      (C) to provide protection against short circuiting   

      (D) to lubricate the moving part  

Answer: (A)

  52- Full load copper loss in a transformer is 1600 watts. At half load the loss will be

       (A)   6400 W 

       (B) 1600 W  

       (C) 800 W  

       (D) 400 W  

Answer: (D)

   53- Iron loss for transformer is 400 watts .if the transformer is working at its maximum efficiency then copper loss will be 

       

       (A)   1600 watts  

       (B) 400 watts  

       (C) 200 watts 

       (D) 100 watts  

Answer: (B)

    54- A transformer working under conditions of the maximum efficiency has total losses of 1600 W. While operating at half load, the copper loss will be

      

       (A)   800 W 

       (B) 400 W    

       (C) 200 W  

       (D) 100 W 

Answer: (C)

  55- A transformer has full load copper loss of 800 W and core loss of 600 W .Total losses at no load   will be approx.

        

       (A)   1400 W 

       (B) 1100 W  

       (C) 1000 W 

       (D) 600 W 

Answer: (D)

   56- The Buchholz relay is used on 

       

      (A)   Air cooled transformer 

      (B) Oil cooled transformer  

      (C) welding transformer 

      (D) furnace transformer  

Answer: (B)

   57- Buchholz relay is not generally provided on transformers below 

      (A)   1 kVA 

      (B) 5 kVA  

\    (C) 50 kVA 

      (D) 500 kVA 

Answer: (D)

   58-Operating time for the Buchholz relay is of the order of 

       (A)   0.1 micro second 

       (B) 0.1 milli second 

       (C) 0.1 second 

       (D) 1 second

Answer: (C)

   59- In a distribution transformer, normally   

       

       (A)   Core losses are equal to the copper losses 

       (B) core losses are more than copper losses   

       (C) core losses are less than copper losses

       (D) core losses are half of the copper losses

Answer: (C)

  60- A Buchholz relay will operate in a transformer whenever there is 

        (A)   Large internal fault 

        (B) saturation of magnetic circuit 

        (C) over load  

        (D)  any of above

Answer: (A)