Transformer MCQ

Test your knowledge with important Transformer MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30 + more Transformer MCQs at Bissoy

• For a transformer given of 100 kVA, 220/6000-V transformer, short circuit test is performed. What current rating is needed?
  ক

  445A

  খ

  40A

  গ

  60A

  ঘ

  30A
• For a transformer with primary turns 100, secondary turns 400, if 200 V is applied at primary we will get ___________
  ক

  3200 V at secondary

  খ

  1600 V at secondary

  গ

  800 V at secondary

  ঘ

  80 V at secondary
• Core flux in the transformer is _______________
  ক

  square wave

  খ

  triangular

  গ

  sinusoidal

  ঘ

  flat-topped
• Insulation of HVDC transformers should be ___________
  ক

  no need of insulation

  খ

  can be dry or wet

  গ

  wet always

  ঘ

  dry always
• Welding transformers work on principle that weld is actually __________________
  ক

  open circuit

  খ

  short circuit

  গ

  circuit with finite resistance

  ঘ

  circuit with finite reactance
• What will happen if the secondary of a current transformer is open-circuited?
  ক

  depends on other parameters

  খ

  cool as there is no secondary current

  গ

  hot because primary will carry heavy current

  ঘ

  hot because of heavy iron losses
• Which of the following is not a routine test for transformers?
  ক

  Polarity test

  খ

  Radio interference test

  গ

  Core insulation voltage test

  ঘ

  Impedance test
• Why shell type 3-phase transformer is used in large power transforming applications?
  ক

  Due to other reasons

  খ

  More height and less height flexibility

  গ

  Can be made with less height

  ঘ

  Can be made with more height
• Which type of winding is used in 3-phase shell-type transformer?
  ক

  Cylindrical type

  খ

  Circular type

  গ

  Rectangular type

  ঘ

  Sandwich type
• Which of the following is the major requirement for the transformers used for electronic purposes?
  ক

  Constant amplitude voltage gain

  খ

  Perfect DC isolation, maximum efficiency and constant voltage gain

  গ

  Perfect DC isolation

  ঘ

  Maximum efficiency
• For a 20kVA transformer with a turn ratio of 0.4 what amount of total power is transferred inductively?
  ক

  10kVA

  খ

  8kVA

  গ

  50kVA

  ঘ

  12kVA
• Which of the following is the main advantage of an auto-transformer over a two-winding transformer?
  ক

  Eddy losses are totally eliminated

  খ

  Copper losses are negligible

  গ

  Saving in winding material

  ঘ

  Hysteresis losses are reduced
• No-load current in the transformer is _______
  ক

  Sinusoidal distorted

  খ

  Sinusoidal

  গ

  Steps

  ঘ

  Straight DC
• Voltage regulation of transformer is given by _____________
  ক

  V2-E2/E2

  খ

  V2-E2/V2

  গ

  E2-V2/V2

  ঘ

  E2-V2/E2
• For a power transformer operating at full load it draws voltage and current equal to 200 V and 100 A respectively at 0.8 pf. Iron and copper losses are equal to 120 kW and 300kW. What is efficiency?
  ক

  97.44%

  খ

  99.12%

  গ

  86.44%

  ঘ

  96.44%
• Power transformers other than distribution transformers are generally designed to have maximum efficiency around ______
  ক

  10% overload

  খ

  Near full-load

  গ

  Half-load

  ঘ

  No-load
• The full-load copper loss of a transformer is 1600 W. At half-load, the copper loss will be _______
  ক

  1600 W

  খ

  6400 W

  গ

  400 W

  ঘ

  800 W
• A 25 KVA transformer is constructed to a turns ratio of N1/N2 = 10. The impedance of primary winding is 3+j5 ohms and of secondary winding is 0.5+j0.8 ohms. What will be the impedance of transformer when referred to primary?
  ক

  53 + 85j ohms

  খ

  53j + 85 ohms

  গ

  Can’t be calculated

  ঘ

  3.5 + 5.8j ohms
• For a transformer with primary turns 400, secondary turns 100, if 20A current is flowing through primary, we will get ___________
  ক

  800A at secondary

  খ

  40A at secondary

  গ

  80A at secondary

  ঘ

  5A at secondary
• Which transformer insulation material is best compare to Kraft paper?
  ক

  Asbestos

  খ

  Oil

  গ

  Cotton

  ঘ

  Low grade pressboard
• An ideal transformer will have maximum efficiency at a load such that _____________
  ক

  copper loss > iron loss

  খ

  cannot be determined

  গ

  copper loss = iron loss

  ঘ

  copper loss < iron loss
• What is the function of a breather in a transformer?
  ক

  To arrest flow of moisture when outside air enters the transformer

  খ

  To cool the transformer oil

  গ

  To provide oxygen inside the tank

  ঘ

  To cool the coils during reduced load
• Which of the following transformer, Buchholz’s relay can be fixed on?
  ক

  Welding transformers

  খ

  Oil cooled transformers

  গ

  Auto-transformers

  ঘ

  Air-cooled transformers
• Primary winding of a transformer ______________
  ক

  Could either be a low voltage or high voltage winding

  খ

  Is always a high voltage winding

  গ

  Cannot be determined

  ঘ

  Is always a low voltage winding
• Which type of flux does transformer action need?
  ক

  Alternating electric flux

  খ

  Alternating magnetic flux

  গ

  Increasing magnetic flux

  ঘ

  Constant magnetic flux
• What is the thickness of laminations used in a transformer?
  ক

  14 mm to 15 mm

  খ

  25 mm to 40 mm

  গ

  0.1 mm to 0.5 mm

  ঘ

  4 mm to 5 mm
• Transformers are generally designed for ___________
  ক

  one-time use

  খ

  off-site problem solving

  গ

  short-time use

  ঘ

  on-site problem solving
• The purpose of the transformer core is to provide ____________
  ক

  Low reluctance path

  খ

  High inductive path

  গ

  High capacitive path

  ঘ

  High reluctance path
• Transformer core is generally made of ___________
  ক

  Cannot be determined

  খ

  Can be made with any of the above method

  গ

  By stacking large number of sheets together

  ঘ

  Single block of core material
• Which of the following is not a part of transformer installation?
  ক

  Breather

  খ

  Conservator

  গ

  Exciter

  ঘ

  Buchholz relay