# 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?

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

## Related Questions

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

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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.

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A transformer operates 24 hours day at full -load. It's full -load efficiency is :  (A) equal all day efficiency (B) more than all -day efficiency (C) less than all -day efficiency (D) equal to maximum efficiency
Last Answer : A transformer operates 24 hours day at full -load. It's full -load efficiency is : equal all day efficiency

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Last Answer : Generators for peak load plants are usually designed for maximum efficiency at 50 to 75 percent full load.

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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.

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

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

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Three identical resistors connected in star consume 5000 W. If the resistors are connected in delta across the same supply, the power consumed will be
Last Answer : Three identical resistors connected in star consume 5000 W. If the resistors are connected in delta across the same supply, the power consumed will be 15000 W

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Last Answer : The direction of rotation of an hysteresis motor is determined by position of shaded pole with respect to main pole.

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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

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Last Answer : In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

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

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Last Answer : Winding will be damaged

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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.

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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.

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Last Answer : Short circuit test on transformers is conducted to determine copper losses.

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Last Answer : Necessary conditions required to be satisfied in order to ensure successful parallel operation of single phase transformers:  1. Only transformers having the same phase displacement between primary and secondary ... . 7. The phase sequence must be followed strictly on HV and LV side connection.

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

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Losses which occur in rotating electric machines and do not occur in transformers are?
Last Answer : Friction losses windage losses

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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

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Explain the concept of initial and final conditions in switching for L and C.
Last Answer : i) Inductor: The current through an inductor cannot change instantly. If the inductor current is zero just before switching, then whatever may be the applied voltage, just after switching the inductor ... open-circuit.  The initial and final conditions are summarized in following table:

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The efficiency of a transformer, under heavy loads, is comparatively low because?
Last Answer : The efficiency of a transformer, under heavy loads, is comparatively low because copper loss becomes high in proportion to the output.

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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%.

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

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[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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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.

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Negative voltage regulation is indicative that the load is?
Last Answer : Negative voltage regulation is indicative that the load is capacitive.

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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.

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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.

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Minimum voltage regulation occurs when the power factor of the load is?
Last Answer : Minimum voltage regulation occurs when the power factor of the load is leading.

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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.

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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

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Last Answer : A common method of cooling a power transformer is oil cooling.

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

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TRANSFORMERS MCQ
Last Answer : 101. A shell-type transformer has (a) high eddy current losses (b) reduced magnetic leakage (c) negligibly hysteresis losses (d) none of the above Ans: b 102. A transformer can have regulation closer to zero (a ... (6) much smaller (c) much higher (d) somewhat smaller (e) none of the above Ans: c

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What are the schedules of maintenance done on transformers?
Last Answer : Ans. Following are the schedules of maintenance on transformers. a. Daily maintenance. b. Monthly maintenance. c. Quarterly maintenance. d. Half yearly maintenance. e. Yearly maintenance. f. 5 Yearly maintenance.

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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).

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What are the loses in Transformers, Explain?
Last Answer : Ans. (1) Iron loses (2) Copper loses Iron Loss : Iron loss occurs in the transformers Iron core due to hysteresis and eddy currents taking place. They are almost fixed irrespective of ... losses in the primary and the secondary windings of the transformer which with the loading of transformer.

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Classify the transformers based on the construction, frequency and power.
Last Answer : Classification of Transformer Based On: i) Construction: Shell type, Core type, Berry type ii) Change in voltage level: Step-Up, Step-Down, iii) Number of phases: Single phase, Three phase iv) ... Control vi) Cooling: Self-cooled, Air-cooled, Forced-air cooled, Oil-cooled, Forced-oil cooled.

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Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary
Last Answer : Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary

578 views 1 answer

Two transformers A and B having equal outputs and voltage ratios but unequal percentage impedances of 4 and 2 are operating in parallel. The transformer A will be overloaded by
Last Answer : Two transformers A and B having equal outputs and voltage ratios but unequal percentage impedances of 4 and 2 are operating in parallel. The transformer A will be overloaded by 33%

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Core type transformers are popular in___________.  (A) High voltage applications (B) Low voltage applications (C) All of the above (D) None of the above
Last Answer : Core type transformers are popular in High voltage applications

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In a transmission line if booster transformers are to be used, preferred location will be  (A) At the receiving end (B) At the sending end (C) At the intermediate point (D) Anywhere in the line
Last Answer : In a transmission line if booster transformers are to be used, preferred location will be At the intermediate point

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

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Two 3-phase transformers cannot be operated in parallel, if their :  (A) kVAs are different (B) phase sequences are different (C) % impedances are different (D) voltage ratios are different
Last Answer : Two 3-phase transformers cannot be operated in parallel, if their : phase sequences are different

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

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Which of the following is the advantage of using CRGO steel in transformers? A) High magnetic flux density B) Low permeability C) Both A and B D) None of these
Last Answer : It definitely High Magnetic Flux Density since a crgo steel has always a more around 3% of silicon proportion among the remaining ferrite which make cold rolled grain oriented steel having high flux magnetic ... for more about the crgo core you can learn here https://nicoreindia.com/crgo-core/

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Last Answer : Instrument transformers are potential transformers, current transformers.

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What is the back EMF in Transformers?