The term 'cogging' is associated with
The term 'cogging' is associated with
During short circuit test iron losses are negligible because
During short circuit test iron losses are negligible because
The 'crawling' in an induction motor is caused by
The 'crawling' in an induction motor is caused by
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
The core used in high frequency transformer is usually
The core used in high frequency transformer is usually
Hysteresis loss in a transformer varies as (Bmax = maximum flux density)
Hysteresis loss in a transformer varies as (Bmax = maximum flux density)
When a given transformer is run at its rated voltage but reduced frequency, its
When a given transformer is run at its rated voltage but reduced frequency, its
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
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
The permissible flux density in case of cold rolled grain oriented steel is around
The permissible flux density in case of cold rolled grain oriented steel is around
The use of higher flux density in the transformer design
The use of higher flux density in the transformer design
In an actual transformer the iron loss remains practically constant from noload to fullload because
In an actual transformer the iron loss remains practically constant from noload to fullload because
The chemical used in breather is
The chemical used in breather is
Open circuit test on transformers is conducted to determine
Open circuit test on transformers is conducted to determine
Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
In a transformer the resistance between its primary and secondary should be
In a transformer the resistance between its primary and secondary should be
A transformer can have regulation closer to zero
A transformer can have regulation closer to zero
An ideal transformer is one which has
An ideal transformer is one which has
When the equivalent circuit diagram of doouble squirrelcage induction motor is constructed the two cages can be considered
When the equivalent circuit diagram of doouble squirrelcage induction motor is constructed the two cages can be considered
Star/star transformers work satisfactorily when
Star/star transformers work satisfactorily when
In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues?
In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues?
Buchholz's relay gives warning and protection against
Buchholz's relay gives warning and protection against
The full-load copper loss of a transformer is 1600 W. At half-load, the copper loss will be
The full-load copper loss of a transformer is 1600 W. At half-load, the copper loss will be
Which of the following is the main advantage of an auto-transformer over a two winding transformer?
Which of the following is the main advantage of an auto-transformer over a two winding transformer?
Which motor is preferred for use in mines where explosive gases exist?
Which motor is preferred for use in mines where explosive gases exist?
An ideal transformer will have maximum efficiency at a load such that
An ideal transformer will have maximum efficiency at a load such that
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
In a transformer routine efficiency depends upon
In a transformer routine efficiency depends upon
The power transformer is a constant
The power transformer is a constant
The size of a transformer core will depend on
The size of a transformer core will depend on
Noise level test in a transformer is a
Noise level test in a transformer is a
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
Sumpner's test is conducted on transformers to determine
Sumpner's test is conducted on transformers to determine
Delta/star transformer works satisfactorily when
Delta/star transformer works satisfactorily when
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
In case of a double cage induction motor, the inner cage has
In case of a double cage induction motor, the inner cage has
Which of the following is not the standard voltage for power supply in India?
Which of the following is not the standard voltage for power supply in India?
The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 Ω load. The turns ratio is 3:1. What is the secondary voltage?
The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 Ω load. The turns ratio is 3:1. What is the secondary voltage?
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
The function of breather in a transformer is
The function of breather in a transformer is
Greater the secondary leakage flux
Greater the secondary leakage flux
A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 Ω. The load resistance as seen by the source is
A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 Ω. The load resistance as seen by the source is
The dielectric strength of transformer oil is expected to be
The dielectric strength of transformer oil is expected to be
The degree of mechanical vibrations produced by the laminations of a transformer depends on
The degree of mechanical vibrations produced by the laminations of a transformer depends on
Helical coils can be used on
Helical coils can be used on
No-load current in a transformer
No-load current in a transformer
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
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
For given applied voltage, with the increase in frequency of the applied voltage
For given applied voltage, with the increase in frequency of the applied voltage
Power transformers are designed to have maximum efficiency at
Power transformers are designed to have maximum efficiency at
The value of flux involved m the e.m.f. equation of a transformer is
The value of flux involved m the e.m.f. equation of a transformer is
The transformer oil should have _____ volatility and _____ viscosity.
The transformer oil should have _____ volatility and _____ viscosity.
The transformer laminations are insulated from each other by
The transformer laminations are insulated from each other by
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 ?
The hum in a transformer is mainly attributed to
The hum in a transformer is mainly attributed to
The no-load current drawn by transformer is usually what per cent of the full-load current?
The no-load current drawn by transformer is usually what per cent of the full-load current?
The highest voltage for transmitting electrical power in India is
The highest voltage for transmitting electrical power in India is
The purpose of providing iron core in a step-up transformer is
The purpose of providing iron core in a step-up transformer is
Which of the following does not change in a transformer?
Which of the following does not change in a transformer?
Which of the following is not a routine test on transformers?
Which of the following is not a routine test on transformers?
A transformer transforms
A transformer transforms
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 Buchholz relay can be installed on
A Buchholz relay can be installed on
During open circuit test of a transformer
During open circuit test of a transformer
The purpose of providing an iron core in a transformer is to
The purpose of providing an iron core in a transformer is to
The chemical used in breather for transformer should have the quality of
The chemical used in breather for transformer should have the quality of
The starting torque of a squirrel-cage induction motor is
The starting torque of a squirrel-cage induction motor is
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?
The function of conservator in a transformer is
The function of conservator in a transformer is
Minimum voltage regulation occurs when the power factor of the load is
Minimum voltage regulation occurs when the power factor of the load is
If a transformer is switched on to a voltage more than the rated voltage
If a transformer is switched on to a voltage more than the rated voltage
The noise resulting from vibrations of laminations set by magnetic forces, is termed as
The noise resulting from vibrations of laminations set by magnetic forces, is termed as
The power factor of an induction motor under no-load conditions will be closer to
The power factor of an induction motor under no-load conditions will be closer to
Short circuit test on transformers is conducted to determine
Short circuit test on transformers is conducted to determine
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
Losses which occur in rotating electric machines and do not occur in trans formers are
Losses which occur in rotating electric machines and do not occur in trans formers are
The path of a magnetic flux in a transformer should have
The path of a magnetic flux in a transformer should have
Negative voltage regulation is indicative that the load is
Negative voltage regulation is indicative that the load is
A good voltage regulation of a transformer means
A good voltage regulation of a transformer means
The no load current in a transformer lags behind the applied voltage by an angle of about
The no load current in a transformer lags behind the applied voltage by an angle of about
In a transformer the resistance between its primary and secondary is
In a transformer the resistance between its primary and secondary is
Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds
Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds
In the transformer following winding has got more cross-sectional area
In the transformer following winding has got more cross-sectional area
A transformer core is laminated to
A transformer core is laminated to
An ideal transformer has infinite values of primary and secondary inductances. The statement is
An ideal transformer has infinite values of primary and secondary inductances. The statement is
A transformer oil must be free from
A transformer oil must be free from
Which type of winding is used in 3phase shell-type transformer?
Which type of winding is used in 3phase shell-type transformer?
For the parallel operation of single phase transformers it is necessary that they should have
For the parallel operation of single phase transformers it is necessary that they should have
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?
No-load on a transformer is carried out to determine
No-load on a transformer is carried out to determine
The path of the magnetic flux in transformer should have
The path of the magnetic flux in transformer should have
Primary winding of a transformer
Primary winding of a transformer
The changes in volume of transformer cooling oil due to variation of atmospheric tem-perature during day and night is taken care of by which part of transformer
The changes in volume of transformer cooling oil due to variation of atmospheric tem-perature during day and night is taken care of by which part of transformer
Two transformers operating in parallel will share the load depending upon their
Two transformers operating in parallel will share the load depending upon their
A transformer cannot raise or lower the voltage of a D.C. supply because
A transformer cannot raise or lower the voltage of a D.C. supply because
The thickness of laminations used in a transformer is usually
The thickness of laminations used in a transformer is usually
If the percentage impedances of the two transformers working in parallel are different, then
If the percentage impedances of the two transformers working in parallel are different, then
No-load current of a transformer has
No-load current of a transformer has
Which of the following does not change in an ordinary transformer?
Which of the following does not change in an ordinary transformer?
Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is
Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is
In a transformer the tappings are generally provided on
In a transformer the tappings are generally provided on
