Transformers Multiple Choice Questions and Answers pdf download free

1.      Which of the following does not change in a transformer ?
2.      In a transformer the energy is conveyed from primary to secondary
3.    A transformer core is laminated to
4.    The degree of mechanical vibrations produced by the laminations of a transformer depends on
5.    The no-load current drawn by transformer is usually what per cent of the full-load current ?
6.    The path of a magnetic flux in a transformer should have
7.    No-load on a transformer is carried out to determine
8.    The dielectric strength of transformer oil is expected to be
9.      Sumpner's test is conducted on trans-formers to determine
10.    The permissible flux density in case of cold rolled grain oriented steel is around
11.    The efficiency of a transformer will be maximum when
12.    No-load current in a transformer
13.    The purpose of providing an iron core in a transformer is to
14.    Which of the following is not a part of transformer installation ?
15.    While conducting short-circuit test on a transformer the following side is short circuited
16.     In the transformer following winding has got more cross-sectional area
17.     A transformer transforms
18.    A transformer cannot raise or lower the voltage of a D.C. supply because
19.    Primary winding of a transformer
20.    Which winding in a transformer has more number of turns ?
21.    Efficiency of a power transformer is of the order of
22.    In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are
23.    A common method of cooling a power transformer is
24.    The no load current in a transformer lags behind the applied voltage by an angle of about
25.    In a transformer routine efficiency depends upon
26.    In the transformer the function of a conservator is to
27.    Natural oil cooling is used for transformers upto a rating of
28.    Power transformers are designed to have maximum efficiency at
29.    The maximum efficiency of a distribution transformer is
30.    Transformer breaths in when
31.    No-load current of a transformer has
32.    Spacers are provided between adjacent coils
33.    Greater the secondary leakage flux
34.    The purpose of providing iron core in a step-up transformer is
35.    The power transformer is a constant
36.    Two transformers operating in parallel will share the load depending upon their
37.    If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be
38.    What will happen if the transformers working in parallel are not connected with regard to polarity ?
39.    Ifthe percentage impedances of the two transformers working in parallel are different, then
40.    In a transformer the tappings are generally provided on
41.    The use of higher flux density in the transformer design
42.    The chemical used in breather for transformer should have the quality of
43.    The chemical used in breather is
44.    An ideal transformer has infinite values of primary and secondary inductances. The statement is
45.    The transformer ratings are usually expressed in terms of
46.    The noise resulting from vibrations of laminations set by magnetic forces, is termed as
47.    Hysteresis loss in a transformer varies as CBmax = maximum flux density)
48.    Material used for construction of transformer core is usually
49.    The thickness of laminations used in a transformer is usually
50.    The function of conservator in a transformer is
51.    The highest voltage for transmitting electrical power in India is
52.    In a transformer the resistance between its primary and secondary is
53.    A transformer oil must be free from
54.    A Buchholz relay can be installed on
55.    Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds
56.    The main reason for generation of harmonics in a transformer could be
57.    Distribution transformers are generally designed for maximum efficiency around
58.    Which of the following property is not necessarily desirable in the material for transformer core ?
59.    Star/star transformers work satisfactorily when
60.    Delta/star transformer works satisfactorily when
61.    Buchholz's relay gives warning and protection against
62.    The magnetising current of a transformer is usually small because it has
63.    Which of the following does not change in an ordinary transformer ?
64.    Which of the following properties is not necessarily desirable for the material for transformer core ?
65.    The leakage flux in a transformer depends upon
66.    The path of the magnetic flux in transformer should have
67.    Noise level test in a transformer is a
68.    Which of the foJIowing is not a routine test on transformers ?
69.    A transformer can have zero voltage regulation at
70.    Helical coils can be used on
71.    Harmonics in transformer result in
72.    The core used in high frequency transformer is usually
73.     The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be
74.     The value of flux involved m the e.m.f. equation of a transformer is
75.     Silicon steel used in laminations mainly reduces
76.     Which winding of the transformer has less cross-sectional area ?
77.     Power transformers are generally designed to have maximum efficiency around
78.     Which of the following is the main advantage of an auto-transformer over a two winding transformer ?
79.     During short circuit test iron losses are negligible because
80.     Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
81.    The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer
82.    An ideal transformer is one which has
83.    When a given transformer is run at its rated voltage but reduced frequency, its
84.    In an actual transformer the iron loss remains practically constant from noload to fullload because
85.    An ideal transformer will have maximum efficiency at a load such that
86.    If the supply frequency to the transformer is increased,"the iron loss will
87.    Negative voltage regulation is indicative that the load is
88.    Iron loss of a transformer can be measured by
89.    When secondary of a current transformer is open-circuited its iron core will be
90.    The transformer laminations are insulated from each other by
91.    Which type of winding is used in 3phase shell-type transformer ?
92.    During open circuit test of a transformer
93.    Open circuit test on transformers is conducted to determine
94.    Short circuit test on transformers is conducted to determine
95.    For the parallel operation of single phase transformers it is necessary that they should have
96.    The transformer oil should have _____ volatility and _____ viscosity.
97.    The function of breather in a transformer is
98.    The secondary winding of which of the following transformers is always kept closed ?
99.    The size of a transformer core will depend on
100.    N atural air coo ling is generally restricted for transformers up to
101.    A shell-type transformer has
102.    A transformer can have regulation closer to zero
103.    A transformer transforms
104.    Which of the following is not the standard voltage for power supply in India ?
105.    Reduction in core losses and increase in permeability are obtained with transformer employing
106.    In a power or distribution transformer about 10 per cent end turns are heavily insulated
107.    For given applied voltage, with the increase in frequency of the applied voltage
108.    Losses which occur in rotating electric machines and do not occur in trans formers are
109.    In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are
110.    Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect ?
111.    The secondary of a current transformer is always short-circuited under operating conditions because it
112.    In a transformer the resistance between its primary and secondary should be
113.    A good voltage regulation of a transformer means
114.    For a transformer, operating at constant load current, maximum efficiency will occur at
115.    Which of the following protection is normally not provided on small distribution transformers ?
116.    Which of the following acts as a protection against high voltage surges due to lightning and switching ?
117.    The efficiency of two identical transformers under load conditions can be determined by
118.    Which of the following insulating materials can withstand the highest temperature safely ?
119.    Which of the following parts of a transformer is visible from outside ?
120.    The noise produced by a transformer is termed as
121.    Which of the following loss in a transformer is zero even at full load ?
122.    Which of the following is the most likely source of harmonics in a transformer ?
123.    If a transformer is continuously operated the maximum temperature rise will occur in
124.    The hum in a transformer is mainly attributed to
125.    The maximum load that a power transformer can carry is limited by its
126.    The efficiency of a transformer, under heavy loads, is comparatively low because
127.    An open-circuit test on a transformer is conducted primarily to measure
128.    A no-load test is performed on a transformer to determine
129.    The voltage transformation ratio of a transformer is equal to the ratio of
130.    Part of the transformer which is most subject to damage from overheating is
131.    If a transformer is switched on to a voltage more than the rated voltage
132.    Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is
133.    Minimum voltage regulation occurs when the power factor of the load is
134.    In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of
135.    The efficiencies of transformers compared with that of electric motors of the same power are

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