Transformer mcq objective questions and answers part2

Q1. Harmonics in transformer result in
(A) increased core losses
(B) increased I2R losses
(C) magnetic interference with communication circuits
(D) all of the above

Q2. The friction losses in real Transformers are _________?
(A) 0
(B) 0.02
(C) 0.25
(D) 0.7

Q3. An Isolation Transformer Has Primary to Secondary turns ratio of __________
(A) 01:02:00
(B) 02:01:00
(C) 01:01:00
(D) Can be any ratio

Q4. In an Auto Transformer, The Primary and Secondary are__________Coupled
(A) Only Magnetically
(B) Only Electrically
(C) Magnetically as well as electrically
(D) None of the above

Q5. The leakage flux in a transformer depends upon
(A) load current
(B) load current and voltage
(C) load current, voltage and frequency
(D) load current, voltage, frequency and power factor

Q6. The magnetizing current of a transformer is usually small because it has
(A) small air gap
(B) large leakage flux
(C) laminated silicon steel core
(D) fewer rotating parts

Q7. The thickness of laminations used in a transformer is usually
(A) 0.4 mm to 0.5 mm
(B) 3 mm to 5 mm
(C) 12 mm to 16 mm
(D) 25 mm to 30 mm

Q8. The chemical used in breather for transformer should have the quality of
(A) ionizing air
(B) absorbing moisture
(C) cleansing the transformer oil
(D) All of these

Q9. In a Transformer , The primary flux is always _________ the secondary flux.
(A) Greater then
(B) Smaller then
(C) Equal
(D) Equal in both step up and Step down Transformer

Q10. What would happen if we operate a 60 Hz Transformer on 50 Hz Source of Supply?
(A) Current will decrease
(B) Current will increase
(C) Current will be same in both cases.
(D) No Effect

Q11. A common method of cooling a power transformer is
(A) natural air cooling
(B) oil cooling
(C) air blast cooling
(D) any of the above

Q12. Silicon steel used in laminations mainly reduces
(A) copper losses
(B) hysteresis loss
(C) eddy current losses
(D) all of the above

Q13. In a transformer the tappings are generally provided on
(A) Primary side
(B) low voltage side
(C) High voltage side
(D) Secondary side

Q14. Sumpners test is conducted on trans-formers to determine which of the following factors?
(A) stray losses
(B) temperature
(C) efficiency
(D) None of these

Q15. The efficiency of two identical transformers under load conditions can be determined by:
(A) back to back test
(B) short circuit test
(C) open circuit test
(D) any of the above

Q16. The use of higher flux density in the transformer design
(A) reduces iron losses
(B) reduces copper losses
(C) reduces weight per kVA
(D) increases part load efficiency

Q17. While conducting short-circuit test on a transformer which of the following side is short circuited?
(A) Primary side
(B) Low voltage side
(C) High voltage side
(D) Secondary side

Q18. The no load current in a transformer lags behind the applied voltage by an angle of about
(A) 75°
(B) 90°
(C) 120°
(D) 180°

Q19. Which of the following is the most likely source of harmonics in a transformer ?
(A) poor insulation
(B) Core saturation
(C) Overload
(D) loose connections

Q20. The path of a magnetic flux in a transformer should have
(A) low resistance
(B) low reluctance
(C) high reluctance
(D) high resistance