The secondary of a current transformer is always short-circuited under operating conditions because it A) avoids core saturation and high v...
Showing posts with label Transformer MCQ. Show all posts
Showing posts with label Transformer MCQ. Show all posts
Sunday, June 9, 2019
For a transformer, operating at constant load current, maximum efficiency will occur at
For a transformer, operating at constant load current, maximum efficiency will occur at A) 0.8 leading power factor B) 0.8 lagging power f...
Which of the following protection is normally not provided on small distribution transformers ?
Which of the following protection is normally not provided on small distribution transformers ? A) Overfluxing protection B) Buchholz rela...
Which of the following acts as a protection against high voltage surges due to lightning and switching ?
Which of the following acts as a protection against high voltage surges due to lightning and switching ? A) Horn gaps B) Thermal overload ...
The noise produced by a transformer is termed as
The noise produced by a transformer is termed as A) zoom B) humming C) ringing D) buzz Show Answer Ans: B) humming "Show An...
Saturday, June 8, 2019
Which of the following is the most likely source of harmonics in a transformer?
Which of the following is the most likely source of harmonics in a transformer? A) poor insulation B) Overload C) loose connections D) C...
If a transformer is continuously operated the maximum temperature rise will occur in
If a transformer is continuously operated the maximum temperature rise will occur in A) core B) windings C) tank D) Any of the above S...
The hum in a transformer is mainly attributed to
The hum in a transformer is mainly attributed to A) load changes B) oil in the transformer C) magnetostriction D) mechanical vibrations ...
The maximum load that a power transformer can carry is limited by its
The maximum load that a power transformer can carry is limited by its A) temperature rise B) dielectric strength of oil C) copper loss D...
Part of the transformer which is most subject to damage from overheating is
Part of the transformer which is most subject to damage from overheating is A) iron core B) copper winding C) winding insulation D) fram...
If supply frequency of a transformer increases, the secondary output voltage of the transformer
If supply frequency of a transformer increases, the secondary output voltage of the transformer A) remains same B) increases. C) decrease...
In transformer minimum voltage regulation occurs when the power factor of the load is
In transformer minimum voltage regulation occurs when the power factor of the load is A) unity B) lagging C) leading D) zero Show Answ...
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of A) less than 15 A B...
The efficiencies of transformers compared with that of electric motors of the same power are
The efficiencies of transformers compared with that of electric motors of the same power are A) about the same B) much smaller C) much hi...
Which of the following loss in a transformer is zero even at full load ?
Which of the following loss in a transformer is zero even at full load ? A) Hysteresis loss B) Eddy current loss C) Core loss D) Frictio...
The efficiency of two identical transformers under load conditions can be determined by
The efficiency of two identical transformers under load conditions can be determined by A) Back-to-Back test B) Short circuit test C) Ope...
The secondary winding of which of the following transformers is always kept closed ?
The secondary winding of which of the following transformers is always kept closed ? A) Current transformer B) Potential transformer C) A...
Which type of winding is used in 3phase shell-type transformer ?
Which type of winding is used in 3phase shell-type transformer ? A) Cylindrical type B) Circular type C) Sandwich type D) None of Above ...
If the supply frequency to the transformer is increased, the iron loss will
If the supply frequency to the transformer is increased, the iron loss will A) remain same B) decrease C) increase D) None of Above Sh...
In a transformer the resistance between its primary and secondary is
In a transformer the resistance between its primary and secondary is A) 0.1 ohm B) infinite C) 1 ohm D) 1000 ohm Show Answer Ans: B...
A Buchholz relay can be installed on
A Buchholz relay can be installed on- A) Welding transformers B) Welding transformers C) Oil cooled transformers D) None of Above Show...
The transformer ratings are usually expressed in terms of
The transformer ratings are usually expressed in terms of A) KVA B) KW C) KVAR D) Volts Show Answer Ans: A) KVA "Show Answe...
The tap changer in an electrical power transformer is provided on
The tap changer in an electrical power transformer is provided on A) LV winding. B) HV winding. C) Either LV or HV winding. D) Both LV a...
Noise of transformer mainly due to
Noise of transformer mainly due to A) noise generated by cooling fans B) magnetostriction in iron core C) mechanical vibration D) None o...
Flash point of transformer insulating oil should be more than
Flash point of transformer insulating oil should be more than A) 100°C. B) 140°C. C) 45°C. D) None of Above Show Answer Ans: B) 140°...
The maximum efficiency of a distribution transformer is
The maximum efficiency of a distribution transformer is A) at full load B) at 50% full load C) at 75% full load D) at 90% full load Sh...
Power transformers are designed to have maximum efficiency at
Power transformers are designed to have maximum efficiency at A) 80% full load B) 50% full load C) Nearly full load D) No load Show An...
In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are
In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are A) Core losses B) Copper l...
Which winding in a transformer has more number of turns?
Which winding in a transformer has more number of turns ? A) Primary winding B) Secondary winding C) High voltage winding D) Low voltage...
While conducting short-circuit test on a transformer the following side is short circuited
While conducting short-circuit test on a transformer the following side is short circuited A) Low voltage side B) High voltage side C) Pr...
Which of the following is not a part of transformer?
Which of the following is not a part of transformer? A) Breather B) Conservator C) Exciter D) Buchholz relay Show Answer Ans: C) Exc...
No-load current in a transformer
No-load current in a transformer A) lags behind the voltage by about 75° B) leads the voltage by about 75° C) lags behind the voltage by ...
The path of a magnetic flux in a transformer should have
The path of a magnetic flux in a transformer should have A) low resistance B) low reluctance C) high resistance D) high reluctance Sho...
The main purpose of performing short circuit test in a transformer is to measure its
The main purpose of performing short circuit test in a transformer is to measure its A) Copper loss B) Transformer all losses C) Core los...
Friday, June 7, 2019
Transformer core are laminated in order to-
Transformer core are laminated in order to- A) Simplify it's construction B) Minimize eddy current loss C) Reduce cost D) Reduce hys...
Iron loss in transformer can be determined by
Iron loss in transformer can be determined by- A) open circuit test. B) short circuit test. C) Both (A) and (B) Option D) None of above ...
Which of the following losses remain constant during normal operation of transformer?
Which of the following losses remain constant during normal operation of transformer? A) Copper loss B) Transformer all losses C) Core lo...
Which one is used for constant street light load?
Which one is used for constant street light load? A) Current transformer B) Constant current transformer C) Power transformer D) Potenti...
The essential condition for parallel operation of two single-phase transformer is that they should have the same
The essential condition for parallel operation of two single-phase transformer is that they should have the same– A) Polarity B) KVA ratin...
A transformer has negative voltage regulation when its load power factor is
A transformer has negative voltage regulation when its load power factor is– A) Lagging B) Leading C) Unity D) None of above Show Answ...
Which of the following losses varies with load in transformer?
Which of the following losses varies with load in transformer? A) Copper loss. B) Core loss C) Transformer all losses D) None of above ...
No-load test on a transformer is carried out to determine-
No-load test on a transformer is carried out to determine- A) Copper loss. B) Magnetising current and no-load current. C) Magnetising cur...
When AC supply is given to the transformer, the flux will depend on
When AC supply is given to the transformer, the flux will depend on A) Current B) Voltage C) Frequency D) Voltage and Frequency Show ...
A transformer transform-
A transformer transform- A) voltage and currrent B) voltage C) currren D) frequency Show Answer Ans: A) voltage and currrent ...
Thursday, June 6, 2019
At relatively light load, transformer efficiency is low because
At relatively light load, transformer efficiency is low because A) transformer losses are high B) secondary output is low C) fixed loss i...
Which of the following is not a basic element of a transformer?
Which of the following is not a basic element of a transformer? A) primary winding B) secondary winding C) mutual flux D) core Show An...
Transformers operating in parallel will share the load depending upon their
Transformers operating in parallel will share the load depending upon their A) Rating B) Percentage impedance. C) Leakage reactance. D) ...
A transformer has negative voltage regulation when its load power factor is
A transformer has negative voltage regulation when its load power factor is– A) lagging B) leading C) unity D) zero Show Answer Ans:...
The input power under no load condition of transformer consists of
The input power under no load condition of transformer consists of A) core losses and very small amount of copper loss in primary. B) copp...
Does the transformer draw any current when secondary is open?
Does the transformer draw any current when secondary is open? A) Yes B) No Show Answer Ans: A) Yes "Show Answer" লেখায় ...