Electrical Studys

1➤ What is Transformer?

a) Transformer is a device used to convert low alternating voltage to a high alternating voltage b) Transformer is a device used to convert alternating current to direct current c) Transformer is a device used to convert low alternating current to a high alternating current d) Transformers are used only for low alternating voltage

2➤ What is the function of a transformer?

a) Transformer is used to step down or up the DC voltages and currentsb) Transformer is used to step down or up the AC voltages and currentsc) Transformer converts DC to AC voltages d) Transformer converts AC to DC voltages

3➤ What is the working principle of a Transformer?

a) Transformer works on the principle of self induction b) Transformer works on the principle of mutual induction c) Transformer works on the principle of ampere law d) Transformer works on the principle of coulomb law

4➤ Transformer ratings are given in _____________

a) kVARb) HP c) kVA d) kW

5➤ What is the current transformer?

a) transformer used with an A.C. voltmeter b) transformer used with an A.C. ammeter c) transformer used with an D.C. voltmeterd) transformer used with an D.C. ammeter

6➤ Current transformers are __________________

a) parallel connected type of instrument transformers b) series connected type of instrument transformers c) parallel connected normal transformers d) series-parallel connected type of instrument transformers

7➤ Which of the following is not a part of transformer installation?

a) Breatherb) Conservator c) Exciter d) Buchholz relay

8➤ Transformer core is generally made of ___________

a) Cannot be determined b) Can be made with any of the above method c) By stacking large number of sheets together d) Single block of core material

9➤ The purpose of the transformer core is to provide ____________

a) High reluctance pathb) High inductive path c) High capacitive path d) Low reluctance path

10➤ Transformers are generally designed for ___________

a) one-time use b) off-site problem solving c) short-time use d) on-site problem solving

11➤ What is the thickness of laminations used in a transformer?

a) 14 mm to 15 mm b) 25 mm to 40 mm c) 0.1 mm to 0.5 mm d) 4 mm to 5 mm

12➤ Primary winding of a transformer ______________

a) Could either be a low voltage or high voltage winding b) Is always a high voltage winding c) Cannot be determined d) Is always a low voltage winding

13➤ Which type of flux does transformer action need?

a) Alternating electric flux b) Alternating magnetic flux c) Increasing magnetic flux d) Constant magnetic flux

14➤ Which of the following transformer, Buchholz’s relay can be fixed on?

a) Welding transformers b) Oil cooled transformers c) Auto-transformers d) Air-cooled transformers

15➤ An ideal transformer will have maximum efficiency at a load such that _____________

a) copper loss > iron loss b) cannot be determined c) copper loss = iron loss d) copper loss < iron loss

16➤ Power transformers other than distribution transformers are generally designed to have maximum efficiency around ______

a) 10% overload b) No-loadc) Half-load d) Near full-load

17➤ Which transformer insulation material is best compare to Kraft paper?

a) Asbestos b) Oil c) Cotton d) Low grade pressboard

18➤ No-load current in the transformer is _______

a) Sinusoidal distorted b) Sinusoidal c) Steps d) Straight DC

19➤ Which of the following is the major requirement for the transformers used for electronic purposes?

a) Constant amplitude voltage gain b) Perfect DC isolation, maximum efficiency and constant voltage gain c) Perfect DC isolation d) Maximum efficiency

20➤ Which type of winding is used in 3-phase shell-type transformer?

a) Cylindrical type b) Circular type c) Rectangular type d) Sandwich type

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