A shell-type transformer has reduced magnetic leakage.
Sandwich type winding is used in 3 phase shell-type transformer.
State any four characteristics of core type transformer.
Characteristics of core type transformer: i) It has one window. ii) It has one magnetic circuit. iii) Core surrounds the winding. iv) Average length of core is more. v) Area of cross ... Better cooling for winding. vii) Mechnical strength is comparatively less. viii) Repair and maintenance is easy.
High voltage winding in a transformer has more number of turns.
No-load current of a transformer has small magnitude and low power factor.
The magnetising current of a transformer is usually small because it has small air gap.
In the transformer low voltage winding has got more cross-sectional area.
An ideal transformer has infinite values of primary and secondary inductances. The statement is false.
High voltage winding of the transformer has less cross-sectional area.
An ideal transformer is one which has no losses and magnetic leakage.
Cylindrical type transformer has: (A) Single magnetic circuit (B) Double magnetic circuit (C) All of the above (D) None of the above
Cylindrical type transformer has: Single magnetic circuit
State why a transformer always have an efficiency of more than 90%.
As transformer is static device with no moving parts, the losses due to friction & windage are completely absent. Hence transformer has efficiency of more than 90%.
Even at no-load, a transformer draws current from the mains. Why?
State and justify which of the following two transformers is better: Transformer A = 4% voltage regulation Transformer B = 6% voltage regulation
Transformer A with 4% voltage regulation is better. Justification: Voltage regulation refers to the percentage change in secondary voltage when load is changed from no-load to full-load with primary voltage ... 4% voltage regulation, which is less as compared to 6% of transformer B, it is better.
No-load current in a transformer lags behind the voltage by about 75°.
The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.
A transformer cannot raise or lower the voltage of a D.C. supply because Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero.
Primary winding of a transformer could either be a low voltage or high voltage winding.
The efficiency of a power transformer is of the order of 98 percent.
The no load current in a transformer lags behind the applied voltage by an angle of about 75°.
In a transformer, routine efficiency depends upon load current and power factor of load.
The maximum efficiency of a distribution transformer is at 50% full load.
The purpose of providing iron core in a step-up transformer is to decrease the magnitude of magnetizing current.
The power transformer is a constant main flux device.
In a transformer, the tappings are generally provided on low voltage side.
The thickness of laminations used in a transformer is usually 0.4 mm to 0.5 mm.
conservator or a reservoir tank for insulating oil in transformer which used for balanced the onload oil level with help of oil level indicator which mount on middle part of reservoir tank.
A transformer oil must be free from moisture.
The main reason for generation of harmonics in a transformer could be saturation of core.
The leakage flux in a transformer depends upon load current.
Noise level test in a transformer is a type test.
The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be 400 W.
The value of flux involved in the e.m.f. equation of a transformer is maximum value.
When a given transformer is run at its rated voltage but reduced frequency, its core flux density is increased.
An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.
Iron loss of a transformer can be measured by low power factor wattmeter.
When secondary of a current transformer is open-circuited its iron core will be?
When secondary of a current transformer is open-circuited its iron core will be hot because of heavy iron losses taking place in it due to high flux density.
During open circuit test of a transformer?
During open circuit test of a transformer primary is supplied rated voltage.
The function of breather in a transformer is to arrest flow of moisture when outside air enters the transformer.
The size of a transformer core will depend on?
The size of a transformer core will depend on frequency and area of the core.
A transformer can have regulation closer to zero on leading power factor.
In a power or distribution transformer about 10 percent end turns are heavily insulated to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns.
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.
The secondary of a current transformer is always short-circuited under operating conditions because it?
The secondary of a current transformer is always short-circuited under operating conditions because it avoids core saturation and high voltage induction.
In a transformer the resistance between its primary and secondary should be?
In a transformer the resistance between its primary and secondary should be infinity.
A good voltage regulation of a transformer means?
A good voltage regulation of a transformer means output voltage fluctuation from no load to full load is least.
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 unity power factor.
The noise produced by a transformer is termed as?
The noise produced by a transformer is termed as hum.
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 windings.
The hum in a transformer is mainly attributed to?
The hum in a transformer is mainly attributed to magnetostriction.
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 voltage ratio.