No-load current of a transformer has?

For a transformer, operating at constant load current, maximum efficiency will occur at?
Last Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.

124 views 1 answer

asked Mar 19, 2018 by anonymous

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?
Last Answer : In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of less than 15A.

156 views 1 answer

asked Mar 19, 2018 by anonymous

In an actual transformer the iron loss remains practically constant from no load to full load because?

In an actual transformer the iron loss remains practically constant from no load to full load because?
Last Answer : In an actual transformer the iron loss remains practically constant from no load to full load because core flux remains practically constant.

113 views 1 answer

asked Mar 19, 2018 by anonymous

A no-load test is performed on a transformer to determine?

A no-load test is performed on a transformer to determine?
Last Answer : A no-load test is performed on a transformer to determine magnetizing current and loss.

124 views 1 answer

asked Mar 19, 2018 by anonymous

The full-load copper loss of a transformer is 1600 W At half-load, the copper loss will be?

Last Answer : The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be 400 W.

149 views 1 answer

asked Mar 19, 2018 by anonymous

An ideal transformer will have maximum efficiency at a load such that?

Last Answer : An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.

204 views 1 answer

asked Mar 19, 2018 by anonymous

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?
Last Answer : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.

152 views 1 answer

asked Mar 19, 2018 by anonymous

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?
Last Answer : The maximum load that a power transformer can carry is limited by its voltage ratio.

133 views 1 answer

asked Mar 19, 2018 by anonymous

The magnetising current of a transformer is usually small because it has?

Last Answer : The magnetising current of a transformer is usually small because it has small air gap.

78 views 1 answer

asked Mar 19, 2018 by anonymous

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?
Last Answer : 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.

165 views 1 answer

asked Mar 19, 2018 by anonymous

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?
Last Answer : The secondary of a current transformer is always short-circuited under operating conditions because it avoids core saturation and high voltage induction.

107 views 1 answer

asked Mar 19, 2018 by anonymous

Explain the effect of Harmonics on the Transformer.

Explain the effect of Harmonics on the Transformer.
Last Answer : Effect of Harmonics on the Transformer: 1. Core loss: Harmonic voltage increases the hysteresis and eddy current losses in the lamination. The amount of the core loss depends on ... small core vibrations. 5. Saturation problem: Sometimes additional harmonic voltage causes core saturation.

130 views 1 answer

asked May 22, 2020 by anonymous

List two special feature of welding transformer.

List two special feature of welding transformer.
Last Answer : Special features of welding transformer: i) It is a step down transformer that reduces the source voltage to a voltage desired according to the demands of the welding process. ii) Having large primary turns and less ... V ii) Secondary voltage - 40 to 60 V iii) Secondary current - 200 to 600 A

154 views 1 answer

asked May 22, 2020 by anonymous

State two applications of isolation transformer

State two applications of isolation transformer
Last Answer : Applications of isolation transformer: i) Isolates the load equipment from supply ground: ii) Reduction of voltage spikes iii) It acts as a decoupling device. iv) Protects loads from harmonic distortion.

54 views 1 answer

asked May 22, 2020 by anonymous

State why a transformer always have an efficiency of more than 90%.

State why a transformer always have an efficiency of more than 90%.
Last Answer : 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%.

279 views 1 answer

asked May 22, 2020 by anonymous

Equivalent circuit of transformer

Equivalent circuit of transformer
Last Answer : Equivalent Circuit Diagram of Transformer Referred to Primary: V1 -Primary Input voltage I1 - Input Current I0- Exciting current/ No load current Im- Magnetizing component ... equivalent of secondary terminal voltage ZL- Load impedance ZL ′- Primary equivalent of load impedance

381 views 2 answers

asked May 17, 2020 by anonymous

Single phase transformer

Single phase transformer
Last Answer : Single phase Transformer Transformer

261 views 1 answer

asked May 16, 2020 by anonymous

What is the use of transformer?

What is the use of transformer?
Last Answer : The use of transformer is to do lower or raise the voltage or currents in an electrical circuit. That's quite so simple.

160 views 1 answer

asked May 15, 2020 by anonymous

Transformer on DC

Write about transformer on DC.
Last Answer : Transformer on DC : Transformer cannot work on DC. Transformer works on electromagnetic induction principle. Electromagnetic induction principle means when flux linking with coil changes and EMF induced in it ... winding insulation will burn. https://youtu.be/TVp_0fIfxqY

248 views 1 answer

asked May 10, 2020 by anonymous

State and justify which of the following two transformers is better: Transformer A = 4% voltage regulation Transformer B = 6% voltage regulation

State and justify which of the following two transformers is better: Transformer A = 4% voltage regulation Transformer B = 6% voltage regulation
Last Answer : 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.

181 views 1 answer

asked Jul 27, 2019 by anonymous

State any four characteristics of core type transformer.

State any four characteristics of core type transformer.
Last Answer : 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.

132 views 1 answer

asked Jul 27, 2019 by anonymous

Explain construction and working of single phase Auto transformer.

Explain construction and working of single phase Auto transformer.
Last Answer : Construction of single phase auto transformer: (i) It has only one winding wound on a laminated circular magnetic core. (ii) The core is made of silicon steel stampings. (iii) The two terminals of the ... help of handle. 5) The same transformer can be used as step-up or step down auto-transformer

347 views 1 answer

asked Jul 26, 2019 by anonymous

The purpose of providing an iron core in a transformer is to?

Last Answer : The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.

205 views 1 answer

asked Mar 19, 2018 by anonymous

In the transformer which winding has got more cross-sectional area?

Last Answer : In the transformer low voltage winding has got more cross-sectional area.

256 views 1 answer

asked Mar 19, 2018 by anonymous

A transformer cannot raise or lower the voltage of a D.C. supply because?

Last Answer : 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.

351 views 1 answer

asked Mar 19, 2018 by anonymous

Primary winding of a transformer?

Last Answer : Primary winding of a transformer could either be a low voltage or high voltage winding.

86 views 1 answer

asked Mar 19, 2018 by anonymous

Which winding in a transformer has more number of turns ?

Last Answer : High voltage winding in a transformer has more number of turns.

363 views 1 answer

asked Mar 19, 2018 by anonymous

Efficiency of a power transformer is of the order of?

Last Answer : The efficiency of a power transformer is of the order of 98 percent.

100 views 1 answer

asked Mar 19, 2018 by anonymous

In a transformer routine efficiency depends upon?

Last Answer : In a transformer, routine efficiency depends upon load current and power factor of load.

133 views 1 answer

asked Mar 19, 2018 by anonymous

The maximum efficiency of a distribution transformer is?

Last Answer : The maximum efficiency of a distribution transformer is at 50% full load.

141 views 1 answer

asked Mar 19, 2018 by anonymous

Transformer breaths in when?

Last Answer : Transformer breaths in when load on it decreases.

90 views 1 answer

asked Mar 19, 2018 by anonymous

The purpose of providing iron core in a step-up transformer is?

Last Answer : The purpose of providing iron core in a step-up transformer is to decrease the magnitude of magnetizing current.

546 views 1 answer

asked Mar 19, 2018 by anonymous

The power transformer is a constant?

Last Answer : The power transformer is a constant main flux device.

63 views 1 answer

asked Mar 19, 2018 by anonymous

In a transformer the tappings are generally provided on?

Last Answer : In a transformer, the tappings are generally provided on low voltage side.

92 views 1 answer

asked Mar 19, 2018 by anonymous

The use of higher flux density in the transformer design?

Last Answer : The use of higher flux density in the transformer design reduces weight per kVA.

126 views 1 answer

asked Mar 19, 2018 by anonymous

The chemical used in breather for transformer should have the quality of?

Last Answer : The chemical used in breather for transformer should have the quality of cleansing the transformer oil.

187 views 1 answer

asked Mar 19, 2018 by anonymous

An ideal transformer has infinite values of primary and secondary inductances. The statement is?

Last Answer : An ideal transformer has infinite values of primary and secondary inductances. The statement is false.

327 views 1 answer

asked Mar 19, 2018 by anonymous

The transformer ratings are usually expressed in terms of?

Last Answer : The transformer ratings are usually expressed in terms of kVA.

318 views 1 answer

asked Mar 19, 2018 by anonymous

Material used for construction of transformer core is usually?

Last Answer : Material used for construction of transformer core is usually silicon steel.

241 views 1 answer

asked Mar 19, 2018 by anonymous

The thickness of laminations used in a transformer is usually?

Last Answer : The thickness of laminations used in a transformer is usually 0.4 mm to 0.5 mm.

98 views 1 answer

asked Mar 19, 2018 by anonymous

The function of conservator in a transformer is?

Last Answer : 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.

177 views 3 answers

asked Mar 19, 2018 by anonymous