Transformers MCQ | Part - 2
1) A transformer
A. Steps up or down dc voltagesB. Changes ac to dc
C. Steps up or down ac voltages
D. Changes dc to ac
Answer: C
2) The primary winding of a transformer has a 120 V ac supply. What is the value of secondary voltage if the turn ratio is 10?
A. 120 V
B. 12 V
C. 12000 V
D. 1200 V
Answer: D
3) Power transformers are designed to have maximum efficiency at
A. No-load
B. 60 % load
C. 80 % load
D. Full load
Answer: D
4) If the supply frequency (f) of a transformer decreases, the effect of frequency on the transformer's secondary output voltage?
A. Remain the same
B. Decreases
C. Increases
D. All of these
Answer: A
5) During the open circuit test of a transformer
A. The secondary is supplied rated KVA.
B. Primary is supplied with no-load current.
C. Primary is supplied current at high voltage.
D. Primary is supplied rated voltage.
Answer: D
6) Lamination of the transformer core is made up of
A. Aluminum
B. Iron
C. Steel
D. Silicon steel
Answer: D
8) Transformer core are laminated in order to
A. Reduce copper loss
B. Minimize eddy current loss
C. Reduce eddy current and hysteresis loss
D. Reduce hysteresis loss
Answer: B
9) A transformer has a primary coil with 1600 loops and a secondary coil with 1200 loops. If the current in the primary coil is 6 Ampere, then what is the current in the secondary coil of a transformer.
A. 5 Ampere
B. 8 Ampere
C. 12 Ampere
D. 7 Ampere
Answer: B
10) The short circuit test in the transformer is performed on
A. High voltage side
B. light voltage side
C. Both
D. Either option a or b.
Answer: A
11) The secondary voltage is 440 Volt, and primary voltage is 220 Volt, then a comparison of the secondary coil and primary coil is
A. 4/1
B. 5/2
C. 2/1
D. 7/5
Answer: C
12) Which test determines the efficiency of two identical transformers under load conditions?
A. Low voltage test
B. Full - load test
C. Back-to-Back (Sumpner's Test)
D. Open circuit test.
Answer: C
13) The transformer ratings are expressed in terms of
A. KW (Kilo-Watt)
B. Volts
C. KVAR (Kilo-Volt-Ampere-Reactive)
D. KVA (Kilo-Volt-Ampere)
Answer: D
14) A transformer has 8 windings in its primary core and 3 in its secondary coil. If the primary voltage is 440 V, find the secondary voltage.
A. 175 V
B. 185 V
C. 155 V
D. 165 V
Answer: D
15) Oil is provided in an oil-filled transformer for
A. Lubrication
B. Cooling
C. Insulation
D. Both cooling and Insulation
Answer: D.
16) A Buchholz relay can be installed on
A. Oil cooled transformers
B. Autotransformers
C. Welding transformers
D. Air-cooled transformers
Answer: A
17) The noise of the transformer primarily due to
A. Mechanical vibration
B. Cooling fan
C. Magnetostriction in an iron core
D. All of the above
Answer: C
18) If a transformer is connected to a direct current supply, what happened?
A. Damage the transformer
B. No effect
C. Operate with low frequency
D. Operate with high frequency
Answer: A
19) Cruciform shape is used in the transformer core to
A. Reduce core reluctance
B. Reduce core loss
C. Reduce copper winding
D. All of the above
Answer: D
20) Which of the following does not change in an ordinary transformer?
A. Current
B. Frequency
C. Voltage
D. All of the above
Answer: B
21) The dielectric strength of transformer oil is expected to be
A. 3 kV
B. 33 kV
C. 330 kV
D. 100 kV
Answer: B
22) In the transformer, the function of a conservator is to
A. Protect the transformer form damage when oil expands due to heating.
B. It provides air for cooling the transformer.
C. It provided colling oil to transformer when transformer needed.
D. None of the above
Answer: A
23) The efficiency of a transformer is maximum when
A. Eddy current loss = iron loss
B. Hysteresis loss = copper loss.
C. Eddy current loss = hysteresis loss
D. Iron loss = Copper loss.
Answer: D
24) Which winding in a transformer has a greater number of turns
A. Constant voltage winding
B. Low voltage winding
C. Secondary winding
D. High voltage winding
Answer: D
25) In a transformer, tappings are usually provided.
A. High voltage side
B. Low voltage side
C. Primary side
D. Both option a and b
Answer: A
26) The highest voltage for transmitting electrical power in India is
A. 1200kV
B. 400 kV
C. 765 kV
D. 66 kV
Answer: A
27) The purpose of a breather in a transformer to
A. Filter the transformer oil
B. Provide cold air in the transformer
C. Absorb moisture of air during breathing
D. None of the above
Answer: C
28) The necessary condition for the parallel operation of two single-phase transformers is that they must have the same.
A. Turn Ratio
B. Polarity
C. KVA Rating
D. Both option a & b
Answer: D
29) The primary purpose of performing a short circuit test in a transformer is to measure its
A. Core loss
B. Iron loss
C. Insulation loss
D. Copper loss
Answer: D
30) The flashpoint of transformer oil must be greater than
A. 100 degree
B. 125 degree
C. 140 degree
D. 160 degree
Answer: C
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