192 views

1 Answer

Answer :

The no load current in a transformer lags behind the applied voltage by an angle of about 75°.

Like 0 like

Please log in or register to answer this question.

Related questions

26 views

Description : 65)No-load current in a transformer A. Lags behind the voltage by about 75 deg B. leads the voltage by about 75 C. lags behind the voltage by about 15 D. leads the voltage by about 15

0 answers
157 views

Description : 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.

1 answer
0 views

Description : An ac voltage V = V0 sin ωt is applied across a pure inductor of inductance L. Find an expression for the current i, flowing in the circuit and show mathematically that the current flowing through it lags behind the ... by a phase angle of π/2. Also draw graphs of V and i versus ωt for the circuit.

0 answers
7 views

Description : No load current in a transformer: (A) lags the applied voltage by 90° (B) lags the applied voltage by somewhat less than 90° (C) leads the applied voltage by 90° (D) leads the applied voltage by somewhat less than 90°

Last Answer : Ans: B The primary input current under no load conditions has to supply (i) iron losses in the core i.e hysteresis loss and eddy current loss (ii) a very small amount of Cu loss in the primary (there being no Cu loss in secondary as it is open)

1 answer
116 views

Description : Even at no-load, a transformer draws current from the mains. Why?

0 answers
99 views

Last Answer : No-load current in a transformer lags behind the voltage by about 75°.

1 answer
75 views

Last Answer : No-load current of a transformer has small magnitude and low power factor.

1 answer
60 views

Description : During short circuit test iron losses are negligible because A. The current on secondary side is negligible B. The voltage on secondary side does not vary C. The voltage applied on primary side is low D. Full-load current is not supplied to the transformer

Last Answer : C) the voltage applied on primary side is low

1 answer
8 views

Description : During short circuit test iron losses are negligible because A. The current on secondary side is negligible B. The voltage on secondary side does not vary C. The voltage applied on primary side is low D. Full-load current is not supplied to the transformer

Last Answer : C) the voltage applied on primary side is low

1 answer
131 views

Description : 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.

1 answer
172 views

Description : 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.

1 answer
116 views

Description : 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.

1 answer
128 views

Description : 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.

1 answer
154 views

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

1 answer
218 views

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

1 answer
133 views

Description : 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.

1 answer
198 views

Description : 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.

1 answer
373 views

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.

1 answer
113 views

Last Answer : When a given transformer is run at its rated voltage but reduced frequency, its core flux density is increased.

1 answer
102 views

Description : A good voltage regulation of a transformer means?

Last Answer : A good voltage regulation of a transformer means output voltage fluctuation from no load to full load is least.

1 answer
182 views

Description : The voltage transformation ratio of a transformer is equal to the ratio of?

Last Answer : The voltage transformation ratio of a transformer is equal to the ratio of secondary induced e.m.f. to primary induced e.m.f.

1 answer
100 views

Description : If a transformer is switched on to a voltage more than the rated voltage?

Last Answer : If a transformer is switched on to a voltage more than the rated voltage its power factor will deteriorate.

1 answer
102 views

Description : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are (A) 140 W (B) 180 W (C) 240 W (D) 480 W

Last Answer : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are 240 W

1 answer
82 views

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

1 answer
170 views

Description : 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.

1 answer
113 views

Description : 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.

1 answer
118 views

Description : The inrush current of a transformer at no load is maximum if the supply voltage is switched on  (1) at peak voltage value (2) at zero voltage value (3) at half voltage value (4) at 0.866 time voltage value

Last Answer : At 0.866 time voltage value

2 answers
177 views

Description : 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.

1 answer
497 views

Description : 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

1 answer
64 views

Description : 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.

1 answer
508 views

Description : 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%.

1 answer
408 views

Description : 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

2 answers
264 views

Description : Single phase transformer

Last Answer : Single phase Transformer Transformer

1 answer
162 views

Description : 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. 

1 answer
250 views

Description : 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

1 answer
149 views

Description : 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.

1 answer
389 views

Description : 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

1 answer
223 views

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

1 answer
265 views

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

1 answer
88 views

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

1 answer
383 views

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

1 answer
118 views

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

1 answer
140 views

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

1 answer
152 views

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

1 answer
95 views

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

1 answer
559 views

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

1 answer
66 views

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

1 answer
96 views

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

1 answer
130 views

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

1 answer
...