Electrical Transformer Multiple choice Question (Electrical Mcqs) and Answer Part 9

       Electrical Engineering Objective Question and Answer  




161- The kVA delivered by transformer I will be 


        (A) 55.5

        (B) 68.4 

        (C) 114.4

        (D) 144

       Answer: (C)

      162- The KVA delivered by transformer 2 will be


        (A) 185.6

        (B) 155.4 

        (C) 114.4


        (D) 100

       Answer: (A)

      163- A transformer has input voltage of 100 V at 400 Hz. if the number of turns is 375, the peak value of flux will be   


        (A) 1.5 μ Wb

        (B) 68.4 μ Wb

        (C) 114.4 μ Wb

        (D) 144 μ Wb

       Answer: (C)

      164- In a transformer on no load, the input voltage  


        (A) leads the magnetizing current by 90°

        (B) lags the magnetizing current by 90°

        (C) is in phase with magnetizing current 

        (D) is always at 45° to the magnetizing current 

       Answer: (A)


     165- In a transformer the voltage induced in the secondary wingdings   


        (A) leads the flux by 90°

        (B) leads the flux by less than 45°

        (C) lags the flux by 90°

        (D) lags the flux by less than 45°

       Answer: (C)

       166- The maximum load that a power transformer can carry is limited by its


        (A) voltage ratio

        (B) copper loss

        (C) temperature rise

        (D) dielectric strength of oil

       Answer: (A)

       167- The losses on a transformer are

       1- copper loss   2- Eddy current loss   3- Hysteresis loss   

       The constant power loss of a transformer loss is given by


        (A) 1 only

        (B) 1 and 2 only

        (C) 2 and 3 only

        (D) 1 ,2 and 3 only

       Answer: (C)

      168- For the circuit shown in figure, the primary current will be   


        (A) 12.8 A

        (B) 8.8 A

        (C) 6.4 A

        (D) 3.2A

       Answer: (C)

       169- which of the following test provides the information about regulation, efficiency and heating under load conditions ?
       
                   

                                                                         Figure-20


        (A)Open circuit test 

        (B) Short circuit test

        (C) Hopkinson's test

        (D) Back to back test

       Answer: (D)

     An open circuit test on a certain transformer produced the following measurements :
      
       Primary   voltage         115 V

       Secondary voltage       57.5 V

       Power                           9.5 W

      No load primary current 180 mA.

      170- the transformer turns ratio is 
     
                          

                                                                                     Fig. 21   


        (A) Ns : Np :: 1 : 2 

        (B) Ns : Np :: 2:1

        (C) Ns : Np :: 2:3

        (D) Ns : Np :: 3:2

       Answer: (A)

    Question 171 to 176 refer to figure below :

     The transformer shown in figure has an alternating input of 100 V. The number of turns on each winding are 

     Np = 375 , Ns1 = 750 , Ns2 = 500 and Ns3 = 75

      171- The output ES1 will be    


        (A) 200 V

        (B) 133 V

        (C) 20 V

        (D) 353 V

       Answer: (B)

      172- The output voltage ES2 will be  


        (A) 200 V

        (B) 133 V

        (C) 20 V

        (D) 353 V

       Answer: (B)

      173- The output voltage Es3 will be  


        (A) 10 V

        (B) 20 V

        (C) 40 V

        (D) 80 V

       Answer: (B)

      174- The total output voltage if all three secondary winding were connected series-aiding, will be 


        (A) 200 V

        (B) 200 x 133 x 20 V

        (C) 353 V

        (D) 353 √2 V

       Answer: (C)

       175- if three secondary windings have load as Rs1 = 1 K Ω .Rs2= 500 Ω and Rs3 = 100 Ω ,                   assuming transformer to be 100% efficient , the maximum current will flow through  


        (A) Rs1

        (B) Rs2

        (C) Rs3


       Answer: (B)

        176- In the above case the total primary current will be  


        (A) 400 mA

        (B) 666 mA

        (C) 705 mA

        (D) 795 mA


       Answer: (D)

       Question 177 and 178 refer to data given below :
    
       An iron-core transformer has a primary inductance of 0.2 H, a  secondary inductance of 50 mH, and a turn ratio of 2:1. The winding resistance are measured as Rp = 2 ohms and Rs = 1 ohm.


         177- The load voltage for a resistor load of 8 ohms and  an input of 16 V at 1 kHz will be  


        (A) 12.8 V

        (B) 8.2 V

        (C) 6.4 V

        (D) 3.2 V


       Answer: (C)

        178- Under no load condition the secondary voltage will be


        (A) 6.4 V

        (B) 12 V

        (C) 10 V

        (D) 8 V


       Answer: (D)

      Question 179 , 180 refer to figures below :

       179- In low frequency range, in case of an iron-core transformer, the output voltage will vary as shown in
          
                   



        (A) figure A

        (B) figure B

        (C) figure C

        (D) figure D


       Answer: (C)

     180- The response of iron core transformer in high frequency range will be as shown in


        (A) figure A

        (B) figure B

        (C) figure C

        (D) figure D


       Answer: (B)









       











      

   

No comments: