A common method of cooling a power transformer is?

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Answer :

A common method of cooling a power transformer is oil cooling.

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Natural oil cooling is used for transformers up to a rating of?

Last Answer : Natural oil cooling is used for transformers up to a rating of 3000 kVA.

Natural air cooling is generally restricted for transformers up to?

Last Answer : Natural air cooling is generally restricted for transformers up to 1.5 MVA .

Why a transformer requires cooling. What are the methods of cooling transformers?

Description : Why a transformer requires cooling. What are the methods of cooling transformers?

Last Answer : Ans. Transformers requires cooling as they get heated up due to various losses taking place in the transformer. (like iron of copper losses) Following are the methods of cooling of transformer. a. Natural ... . Forced oil air Natural Cooling (OFAN). d. Forced oil and forced Air cooling (OFAF).

State the function of cooling tower and condenser in thermal power station.

Description : State the function of cooling tower and condenser in thermal power station.

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Harmonics in transformer result in?

Last Answer : Harmonics in transformer result in increased core losses, increased I2R losses, and magnetic interference with communication circuits.

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Draw and explain the function of cooling tower in TPS.

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Which of the following is used for thermoelectric cooling?

Description : Which of the following is used for thermoelectric cooling? A) Peltier effect B) Seebeck effect C) Both A and B D) None of these

Last Answer : Which of the following is used for thermoelectric cooling? A) Peltier effect B) Seebeck effect C) Both A and B D) None of these

Power transformers are generally designed to have maximum efficiency around?

Last Answer : Power transformers are generally designed to have maximum efficiency around near full-load.

The efficiencies of transformers compared with that of electric motors of the same power are?

Description : The efficiencies of transformers compared with that of electric motors of the same power are?

Last Answer : Transformers have high efficiency than the same ratted motors

If the percentage impedances of the two transformers working in parallel are different, then?

Description : If the percentage impedances of the two transformers working in parallel are different, then?

Last Answer : If the percentage impedances of the two transformers working in parallel are different, then parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load.

Distribution transformers are generally designed for maximum efficiency around?

Last Answer : Distribution transformers are generally designed for maximum efficiency around 50% load.

Two transformers do not have equal percentage impedance. This is likely to result in?

Description : Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in?

Last Answer : Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in loading of the transformers not in proportion to their kVA ratings.

Short circuit test on transformers is conducted to determine?

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For the parallel operation of single phase transformers it is necessary that they should have?

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Losses which occur in rotating electric machines and do not occur in transformers are?

Description : Losses which occur in rotating electric machines and do not occur in transformers are?

Last Answer : Friction losses windage losses 

The efficiency of two identical transformers under load conditions can be determined by?

Description : The efficiency of two identical transformers under load conditions can be determined by?

Last Answer : The efficiency of two identical transformers under load conditions can be determined by back-to-back test.

[23] Transformers are rated in KVA instead of KW because A. load power factor is often not known B. KVA is fixed whereas KW depends on load power factor C. Total transformer loss depends on volt ampere D. It has become customary

Description : [23] Transformers are rated in KVA instead of KW because A. load power factor is often not known B. KVA is fixed whereas KW depends on load power factor C. Total transformer loss depends on volt ampere D. It has become customary

Last Answer : C. Total transformer loss depends on volt ampere

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78 Which type of winding is used in 3 phase shell type transformer? A. Circular type B. Sandwich type C. Cylindrical type D. Rectangular type

Description : 78 Which type of winding is used in 3 phase shell type transformer? A. Circular type B. Sandwich type C. Cylindrical type D. Rectangular type

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73 The full load copper loss of a transformer is 1600W. At half-load the copper loss will be A. 6400W B. 1600W C. 800W D. 400W

Description : 73 The full load copper loss of a transformer is 1600W. At half-load the copper loss will be A. 6400W B. 1600W C. 800W D. 400W

Last Answer : D. 400W

5 The efficiency of a transformer is maximum when A. It runs at half full load B. it runs at full load C. its Cu loss equal iron loss D. it runs over load

Description : 5 The efficiency of a transformer is maximum when A. It runs at half full load B. it runs at full load C. its Cu loss equal iron loss D. it runs over load

Last Answer : C. Its cu loss equal iron loss

State any two conditions for parallel operation of 3-phase transformer.

Description : State any two conditions for parallel operation of 3-phase transformer.

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Compare core type transformer and shell type transformer on the following parameters. (i) Types of winding used, (ii) Application

Description : Compare core type transformer and shell type transformer on the following parameters. (i) Types of winding used, (ii) Application

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Define: (i) Commercial efficiency of a transformer and (ii) All day efficiency of a transformer.

Description : Define: (i) Commercial efficiency of a transformer and  (ii) All day efficiency of a transformer.

Last Answer : (i) Commercial Efficiency : It is the ratio of output power in watt to the input power in watt. (ii) All day efficiency of a transformer: It is the ratio of output energy in kWh to the input energy in kWh in the 24 hours of the day

A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.

Description : A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.

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State any four properties of Ideal transformer.

Description : State any four properties of Ideal transformer.

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Description : Why circuit breaker connect b)w two transformer  (same rating

Last Answer : Because two transformers connection is in parallel to share the load if any transformer is receives the surge current because of the fault so to protect the other transformer from the fault. 

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Description : 74)Power transformers are generally designed to have maximum efficiency around A. No load B. Half load C. Near full load D. 10% overload

Last Answer : C. Near full load

Classify the transformers based on the construction, frequency and power.

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State any two applications of single phase autotransformer.

Description : State any two applications of single phase autotransformer.

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Define transformation ratio in terms of current and voltage.

Description : Define transformation ratio in terms of current and voltage.

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Draw the connection diagram of long shunt differential D.C. compound generator.

Description : Draw the connection diagram of long shunt differential D.C. compound generator.

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Which of the following connection of transformers will give highest value of secondary voltage ?

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Two transformers A and B having equal outputs and voltage ratios but unequal percentage

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In a transmission line if booster transformers are to be used, preferred location will be

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Description : The friction losses in Real Transformers are :  (A) 0% (B) 5% (C) 25% (D) 50%

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Two 3-phase transformers cannot be operated in parallel, if their :

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An additional condition for parallel operation of three-phase transformers over single-phase transformers is that

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Last Answer : An additional condition for parallel operation of three-phase transformers over single-phase transformers is that the transformers should belong to the same vector group

Which of the following is the advantage of using CRGO steel in transformers?

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Instrument transformers are?

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of what use are current and voltage transformers in protective systems

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Why do transformers make noise?

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Last Answer : Transformers make noise based on it out put if an transformer outputs is 400v maximum than a 398v be apply to that transformer it also make a noise because of that 

Three phase step-up transformer installed at power house, just before commencement of transmission line, have:

Description : Three phase step-up transformer installed at power house, just before commencement of transmission line, have:

Last Answer : Three phase step-up transformer installed at power house, just before commencement of transmission line, have: star delta connections

A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at

Description : A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is  (A) 86.7% (B) 88.26% (C) 88.9% (D) 87.8%

Last Answer : A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is 87.8%