In a step-up or step-down transformer, electrical power is transferred from one circuit to another without change in

In a step-up or step-down transformer, electrical power is transferred from one circuit to another without change in
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In a step-up or step-down transformer, electrical power is transferred from one circuit to another without change in frequency

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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?

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.

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

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.

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.

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

Explain direct loading test on single phase transformer with neat circuit diagram.

Description : Explain direct loading test on single phase transformer with neat circuit diagram. 

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:   

Equivalent circuit of transformer

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

A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit

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

During open circuit test of a transformer?

Description : During open circuit test of a transformer?

Last Answer : During open circuit test of a transformer primary is supplied rated voltage.

An open-circuit test on a transformer is conducted primarily to measure?

Description : An open-circuit test on a transformer is conducted primarily to measure?

Last Answer : The open-circuit test in a transformer is used to measure

A capacitor (condenser) is used in an electrical circuit to (a) step down voltage (b) step up voltage (c) store electric charge (d) produce electric charge

Description : A capacitor (condenser) is used in an electrical circuit to (a) step down voltage (b) step up voltage (c) store electric charge (d) produce electric charge

Last Answer : Ans:(c)

When used for taking resistance measurements, a volt-ohm-milliammeter is normally powered by _____________. A. a hand cranked generator B. internal storage batteries C. the current in the circuit being tested D. a step down transformer

Description : When used for taking resistance measurements, a volt-ohm-milliammeter is normally powered by _____________. A. a hand cranked generator B. internal storage batteries C. the current in the circuit being tested D. a step down transformer

Last Answer : Answer: B

what do not change in transformer?

Description : what do not change in transformer?

Last Answer : Frequency and power are constant in transformers. Suppose we apply 50 Hz input frequency then the output frequency will also be 50 Hz whether the transformer is step up or step down. Similar ... is decreased on secondary side and hence power on primary side and secondary side remains constant.

A ground is indicated by the ground-detecting system on the main electrical switchboard. The FIRST step in locating the actual ground is to _____________. A. close all circuit breakers in the distribution panel until the ground detector indicates normal B. open the individual circuit breakers, one by one until the ground detection system indicates normal C. change over generators D. check each circuit with a megohmmeter

Description : A ground is indicated by the ground-detecting system on the main electrical switchboard. The FIRST step in locating the actual ground is to _____________. A. close all circuit breakers in ... ground detection system indicates normal C. change over generators D. check each circuit with a megohmmeter

Last Answer : Answer: B

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%

In a power transformer, the fundamental frequency of the hum arising due to magnetostriction is

Description : In a power transformer, the fundamental frequency of the hum arising due to magnetostriction is  (a) equal to the line frequency (b) double the line frequency (c) 4 times the line frequency (d) not related to the line frequency

Last Answer : In a power transformer, the fundamental frequency of the hum arising due to magnetostriction is double the line frequency

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.

A common method of cooling a power transformer is?

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

The power transformer is a constant?

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

In a power or distribution transformer about 10 percent end turns are heavily insulated?

Last Answer : In a power or distribution transformer about 10 percent end turns are heavily insulated to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns.

The maximum load that a power transformer can carry is limited by its?

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.

A device used in an electrical circuit to change alternating current to direct current, is known as a _____________. A. current transformer B. rectifier C. condenser D. shunt

Description : A device used in an electrical circuit to change alternating current to direct current, is known as a _____________. A. current transformer B. rectifier C. condenser D. shunt

Last Answer : Answer: B

A single-phase, 230 V, 50 Hz ac mains fed step down transformer (4:1) is supplying power to a half-wave

Description : A single-phase, 230 V, 50 Hz ac mains fed step down transformer (4:1) is supplying power to a half-wave uncontrolled ac-dc converter used for charging a battery (12 V dc) with the series current limiting resistor being 19.04 Ohm. The charging current is  (A) 2.43 A (B) 1.65 A (C) 1.22 A (D) 1.0 A

Last Answer : A single-phase, 230 V, 50 Hz ac mains fed step down transformer (4:1) is supplying power to a half-wave uncontrolled ac-dc converter used for charging a battery (12 V dc) with the series current limiting resistor being 19.04 Ohm. The charging current is 1.0 A

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

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

What is an energy that can be transferred from one object to another causing a change in temperature of each object?  A. Power  B. Heat transfer  C. Heat  D. Work

Description : What is an energy that can be transferred from one object to another causing a change in temperature of each object?  A. Power  B. Heat transfer  C. Heat  D. Work

Last Answer : Heat

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 autotransformer B. operational amplifier whose output controls a step-up voltage reactor C. amplitude modulator whose output drives an 2-stage isolation transformer D. magnetic amplifier whose output controls a saturable reactor

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

Last Answer : Answer: D

A three-phase, three-stack, variable reluctance step motor has 20 poles on each rotor and stator stack.

Description : A three-phase, three-stack, variable reluctance step motor has 20 poles on each rotor and stator stack. The step angle of this step motor is  (A) 3o (B) 6o (C) 9o (D) 18o

Last Answer : A three-phase, three-stack, variable reluctance step motor has 20 poles on each rotor and stator stack. The step angle of this step motor is  6o

What is the way to understand transformer step up or step down ?

Description : What is the way to understand transformer step up or step down ?

Last Answer : How to understand the step-up or step-down of a transformer: If the number of patches on the secondary side is more than the primary side of the transformer, then that transformer is a step-up ... than the primary side of the transformer, then that transformer is a step down transformer.

How do I step down a step up transformer ?

Description : How do I step down a step up transformer ?

Last Answer : If we want to step up a transformer, we need to punch more of the secondary coil than the number of punches of the primary coil of the transformer. And in order to determine the number of these ... already been written on our electronics site, I did not repeat it. Read the article from this link.

What are the applications of step-up & step-down transformer?

Description : What are the applications of step-up & step-down transformer?

Last Answer : A:Step-up transformers are used in generating stations. Normally the generated voltage will be either 11kV. This voltage (11kV) is stepped up to 110kV or 220kV or ... and made available at consumer premises. The transformers used at generating stations are called power transformers.

What is transformation ratio for step up, step down and isolation transformer?

Description : What is transformation ratio for step up, step down and isolation transformer?

Last Answer : K>1 for step up transformer K

If output voltage is greater than input voltage, then transformer is A. step up B. step down C. faulty D. fatal

Description : If output voltage is greater than input voltage, then transformer is A. step up B. step down C. faulty D. fatal

Last Answer :  step up

Does 1:5 indicate a step-up or step-down transformer?

Description : Does 1:5 indicate a step-up or step-down transformer?

Last Answer : Step up.

Does 1:5 indicate a step-up or step-down transformer?

Description : Does 1:5 indicate a step-up or step-down transformer?

Last Answer : Step up

Explain the effect of Harmonics on the Transformer.

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.

List two special feature of welding transformer.

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

State two applications of isolation transformer

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.

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

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%.

Single phase transformer

Description : Single phase transformer

Last Answer : Single phase Transformer Transformer

What is the use of transformer?

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. 

Transformer on DC

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

Why phasing out and polarity test is carried out on three phase transformer?

Description : Why phasing out and polarity test is carried out on three phase transformer?

Last Answer : The phasing out test is carried out to identify the windings (primary and secondary) of corresponding phase of the three phase transformer. The polarity test is carried out to identify the ... identical polarity of the primary and secondary windings of each phase of the three phase transformer.

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

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.

State any four characteristics of core type transformer.

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.

Explain construction and working of single phase Auto transformer.

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

If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged,

Description :  If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then: A) both hysteresis loss and eddy current loss in the core will increase B) ... current loss will increase D) hysteresis loss will decrease but eddy current loss will remain unchanged

Last Answer :  If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then: hysteresis loss will decrease but eddy current loss will remain unchanged

Full load copper loss in a transformer is 1600 watts. At half load the copper loss will be:

Description : Full load copper loss in a transformer is 1600 watts. At half load the copper loss will be: A) 6400 watt B) 1600 watt C) 800 watt D) 400 watt

Last Answer :  Full load cupper loss in a transformer is 1600 watts. At half load the cupper loss will be: 400 watt

The current transformer that is used to measure a 100 A current by 5 A ammeter is a_____.

Description : The current transformer that is used to measure a 100 A current by 5 A ammeter is a_____.

Last Answer : The current transformer that is used to measure a 100 A current by 5 A ammeter is a step up transformer

The voltage applied to the H.V. side of a transformer during S.C. test is 2% of the rated voltage. The core loss

Description : The voltage applied to the H.V. side of a transformer during S.C. test is 2% of the rated voltage. The core loss as the fraction of its rated core loss is (a) 4% (b) 0.4% (c) 0.25% (d) 0.04%

Last Answer : 0.04%

When two transformer of different kVA rating are connected in parallel they share the load in proportion to

Description : When two transformer of different kVA rating are connected in parallel they share the load in proportion to their respective kVA rating only when their:

Last Answer : When two transformer of different kVA rating are connected in parallel they share the load in proportion to their respective kVA rating only when their: P u impedance are equal