Multiple Choice Questions and Answers on Transformer - Set 03 - ObjectiveBooks

Multiple Choice Questions and Answers on Transformer - Set 03

Practice Test: Question Set - 03


1. Which of the following is the main advantage of an autotransformer over a two winding transformer?
    (A) Hysteresis losses are reduced
    (B) Saving in winding material
    (C) Copper losses are negligible
    (D) Eddy losses are totally eliminated

2. Helical coils can be used on
    (A) Low voltage side of high kVA transformers
    (B) High frequency transformers
    (C) High voltage side of small capacity transformers
    (D) High voltage side of high kVA rating transformers

3. A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 Ω. What is the approximate voltage across the load?
    (A) 7.3 V
    (B) 73 V
    (C) 88 V
    (D) 880 V

4. A transformer changes ac to dc.
    (A) True
    (B) False

5. When a 200 Ω load resistor is connected across the secondary winding of a transformer with a turns ratio of 4, the source "sees" a reflective load of
    (A) 50 Ω
    (B) 12.5 Ω
    (C) 800 Ω
    (D) 0 Ω

6. If the supply frequency to the transformer is increased, the iron loss will
    (A) Not change
    (B) Decrease
    (C) Increase
    (D) Any of the above

7. Short circuit test on transformers is conducted to determine
    (A) Hysteresis losses
    (B) Copper losses
    (C) Core losses
    (D) Eddy current losses

8. The primary is the winding connected to the source, and the secondary is the winding connected to the load.
    (A) True
    (B) False

9. What is the coefficient of coupling for a transformer in which 4% of the total flux generated in the primary does not pass through the secondary?
    (A) 0.4
    (B) 4
    (C) 9.6
    (D) 0.96

10. Natural air coo ling is generally restricted for transformers up to
    (A) 1.5 MVA
    (B) 5 MVA
    (C) 15 MVA
    (D) 50 MVA

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