What is the importance of equivalent circuit of a transformer?

1 Answer

Answer :

All the parameters of a transformer are graphically andmathematically represented in an equivalent circuit.

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Description : What components compose the excitation current of a transformer. How are they modeled in the transformer's equivalent circuit?

Last Answer : Excitation current Io = Iw + Iu

Description : What components compose the excitation current of a transformer. How are they modeled in the transformer's equivalent circuit?

Last Answer : Excitation current Io = Iw + Iu

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

Description : Explain why the no load current of an induction motor is much higher than that of an equivalent transformer.

Last Answer : In induction motor, due to the presence of the air gap, the magnetizing current that is required to set up the flux is much higher. The working component of the current has to meet the ... eddy current loss, friction and windage losses. Hence the no load current of induction motor is higher.

Description : 50 The equivalent resistance of the primary of the transformer having K = 5, R1 = 0.1 ohm when referred to secondary becomes .....ohm A. 0.5 B. 0.02 C. 0.004 D. 2.5

Last Answer : A. 0.5

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Last Answer : Three wire RTD: Four wire RTD: Three wire configurations is used to help the circuit compensate for lead wire resistance, and thus provide a truer indication of the measured ... the leads. To get the optimum performance, it is generally best to specify the RTD configuration. 

Description : Why is the side-side shorted during the short circuit test in the transformer ?

Last Answer : During this test, any side of the transformer can be shorted, but for the following reasons, the side-side is shorted and 1. Lay-range instruments have the advantage of being connected to the high side ... both windings below 3% of the rated output , so it is convenient to measure on the high side.

Description : What information is available from the short circuit test of the transformer ?

Last Answer : The following information is available from the short circuit test 1. Equivalent resistance ( R.) . 2. Equivalent Reactance ( X.) . 3. Equivalent impedance ( Z.) 4. Copper loss 5. Skills and Regulation

Description : What is the purpose of open circuit test in transformer ?

Last Answer : The following information is obtained from this test and the product is tested in open circuit. Core Loss (Eddy Current Loss and Hysteresis Loss) No-Laid Current Magnetizing Current ( I) Working Current ( I) ... ( R0) Core Loss Reactance ( X) No-Laid Power Factor ( cose,) Transformation Ratio ( a)

Description : What is Open Circuit Test of Transformer ?

Last Answer : Answer : The test is performed at the rated normal full voltage and frequency of the transformer by placing the required number of measuring instruments on either side of the transformer (usually high voltage-side). It is called open circuit test.

Description : What is the reason why wattmeter indicates only copper loss during transformer short circuit test ?

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Description : Which one among the following components can not be developed within an "integrated circuit"? (1) Diode (2) Triode (3) Transformer (4) Transistor

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Description : In electric circuit schematics, a transformer is represented by which of the symbols shown in the illustration? EL-0059 A. A B. B C. C D. D

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Description : In the illustrated circuit, if the input to leads 'B' and 'Y' was 24 VDC the output between 'A' and 'X' will be _________. EL-0069 A. 24 VDC B. 22.8 VDC, 24 VDC minus the 1.2 VDC voltage drop across two diodes C. undeterminable without knowing the turns ratio of the transformer D. 0 VDC

Last Answer : Answer: D

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Last Answer : Answer: B

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Description : The transistors in the illustrated circuit are connected using what type of coupling? EL-0048 A. RC coupling B. transformer coupling C. LC coupling D. direct coupling

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Description : The transistors in the illustrated circuit are connected using what type of coupling? EL-0051 A. RC coupling B. transformer coupling C. impedance coupling D. direct coupling

Last Answer : Answer: D

Description : The transistors in the illustrated circuit are connected using what type of coupling? EL-0050 A. RC coupling B. transformer coupling C. Impedance coupling D. direct coupling

Last Answer : Answer: C

Description : When a fluorescent lamp has reached the end of its useful life, it should be replaced immediately, or the resultant flashing may _____________. A. blow the lamp's circuit breaker B. explode, ... fly in all directions C. short circuit the ballast transformer D. damage the starter and the ballast

Last Answer : Answer: D

Description : Which of the following statements is true concerning a stepdown transformer in an operating AC power circuit? A. Voltage and current will both be increased. B. Voltage and current will both be decreased C. Voltage decreases as current increases. D. Voltage increases as current decreases.

Last Answer : Answer: C

Description : What can be used to replace the exciter in the circuit shown in the illustration? EL-0101 A. A step-up transformer. B. A rectifier. C. A step-down transformer. D. An operational amplifier.

Last Answer : Answer: B

Description : A transformer in an electric circuit serves to ____________. A. generate its own electrical power B. transform electrical energy into mechanical energy C. increase or decrease circuit voltage as required D. convert AC current to DC current

Last Answer : Answer: C

Description : The voltage at the reference electrode of the circuit shown in the illustration is applied to the input of a/an ______________. EL-0090 A. class A detector whose output drives an ... drives an 2-stage isolation transformer D. magnetic amplifier whose output controls a saturable reactor

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Description : Section II of the circuit shown in the illustration is the ____________. EL-0085 A. voltage regulator B. filter C. rectifier D. voltage transformer

Last Answer : Answer: C

Description : Section IV of the circuit shown in the illustration is the _____________. EL-0085 A. voltage regulator B. filter C. rectifier D. voltage transformer

Last Answer : Answer: A

Description : Section III of the circuit shown in the illustration is a _____________. EL-0085 A. voltage regulator B. filter C. rectifier D. voltage transformer

Last Answer : Answer: B

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Description : Explain about the open and short circuit tests on transformer?

Last Answer : A. Open circuit test (No load test) and short circuit test (full load test) are performed on a transformer to determine (i) Equivalent circuit of transformer (ii) Voltage ... determine copper loss in transformer at full load and parameters of approximate equivalent circuit of transformer.

Description : Why the open circuit test on a transformer is conducted at rated voltage?

Last Answer : A:The open circuit on a transformer is conducted at a rated voltage because core loss depends upon the voltage. This open circuit test gives only core loss or iron loss of the transformer.

Description : The short circuit in any winding of the transformer is the result of (a) mechanical vibration (b) insulation failure (c) loose connection (d) impulse voltage

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Description : Which of the following circuit would be preferred for a 455 kHz IF amplifier? A) A resistance loaded B) Double tuned transformer C) Video amplifier D) Class C

Last Answer : B) Double tuned transformer

Description : 66 While conducting short-circuit test on a transformer the following side is short circuited A. High voltage side B. low voltage side C. primary side D. secondary side

Last Answer : B. Low voltage side

Description : 64)During the short-circuit test on a small transformer the frequency is increased from 50-200Hz. The copper losses will increase by a factor of A. 16 B. 4 C. 1 D. 1/4

Last Answer : A) 16

Description : [53] The iron loss of the transformer is negligible during short circuit test because A. The entire input is just sufficient to meet Cu losses only B. Flux produced is a small fraction of the normal flux C. Iron core becomes fully saturated D. Supply frequency is held constant

Last Answer : B. Flux produced is a small fraction of the normal flux

Description : 49 The open circuit test is carried out in a transformer to find the A. Cu loss B. Core loss C. Total loss D. Insulation resistance

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Description : 30 In performing the short circuit test of a transformer A. high voltage is usually short circuited B. low voltage side is usually short circuited C. any side is short circuited with preference D. none of the above

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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

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Last Answer : Direct loading test on single phase transformer with neat circuit diagram:   Direct loading test on transformer is carried out to calculate the losses, efficiency and voltage regulation of the ... voltage.  Efficiency and regulation can be calculated by using following formulae:   

Description : An AC supply of 230 V is applied to half wave rectifier circuit. A transformer turns ratio is 20 : 1. Find i) Output DC voltage (ii) Peak Inverse Voltage (PIV)

Last Answer : Solution:

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

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Description :  An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V 

Last Answer :  An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V 

Description : In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half of the secondary winding is 30 V. Then PIV is: (1) 30 V (2) 60 V (3) 15 V (4) 10 V

Last Answer : In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half of the secondary winding is 30 V. Then PIV is: 60 V

Description : A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit test is performed on it with 90% of the rated currents flowing in its both LV and HV windings, ... .0% of the rated current (C) 80.0% of the rated current (D) 88.8% of the rated current

Last Answer : A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit test is performed on it with 90% of the rated currents flowing in its both ... measured loss is 81 W. The transformer has maximum efficiency when operated at 80.0% of the rated current