Which of the listed transformer uses a single winding to produce voltage transformation? A. Stepup transformers B. Stepdown transformers C. Autotransformers D. Isolation transformers

Which of the listed transformer uses a single winding to produce voltage transformation? A. Stepup transformers B. Stepdown transformers C. Autotransformers D. Isolation transformers
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Answer: C
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When a low input voltage is imparted to a device which then delivers a high output voltage, the device is known as a _____________. A. primary transformer B. secondary transformer C. stepdown transformer D. stepup transformer

Description : When a low input voltage is imparted to a device which then delivers a high output voltage, the device is known as a _____________. A. primary transformer B. secondary transformer C. stepdown transformer D. stepup transformer

Last Answer : Answer: D

Can Transformers be Reconnected as Autotransformers to Increase Their KVA Rating?

Description : Can Transformers be Reconnected as Autotransformers to Increase Their KVA Rating?

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Which of the following statements is true concerning stepdown transformer operation? A. The inductance on the primary side is the same as the inductance on the secondary side. B. The voltage to the primary side is the same as the voltage from the secondary side. C. The current to the primary side is the same as the current from the secondary side. D. The voltage to the primary side is greater than the voltage from the secondary side.

Description : Which of the following statements is true concerning stepdown transformer operation? A. The inductance on the primary side is the same as the inductance on the secondary side. B. The voltage to the primary ... . D. The voltage to the primary side is greater than the voltage from the secondary side.

Last Answer : Answer: D

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.

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

The function of a stepdown potential transformer is to reduce the load _____________. A. voltage and current B. voltage and increase line current C. current and increase line voltage D. power

Description : The function of a stepdown potential transformer is to reduce the load _____________. A. voltage and current B. voltage and increase line current C. current and increase line voltage D. power

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On AC vessels, which of the following statements represents the most difficult problem involved in obtaining a DC potential suitable for use by computer components? A. A stepdown transformer is always required. B. Vessel vibrations affect the voltage source. C. The voltage must be rectified and made ripple free. D. Rectifiers cannot operate with voltage regulators.

Description : On AC vessels, which of the following statements represents the most difficult problem involved in obtaining a DC potential suitable for use by computer components? A. A stepdown transformer is ... voltage must be rectified and made ripple free. D. Rectifiers cannot operate with voltage regulators.

Last Answer : Answer: C

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

The diagram shown in the illustration represents a/an _____________. EL-0082 A. stepup transformer B. magnetic amplifier C. autotransformer D. Scott-connected transformer

Description : The diagram shown in the illustration represents a/an _____________. EL-0082 A. stepup transformer B. magnetic amplifier C. autotransformer D. Scott-connected transformer

Last Answer : Answer: A

The most common source of excitation for synchronous motors is a/an ______________. A. stepup transformer B. half-wave rectifier C. DC supply D. AC supply

Description : The most common source of excitation for synchronous motors is a/an ______________. A. stepup transformer B. half-wave rectifier C. DC supply D. AC supply

Last Answer : Answer: C

The function of the autotransformers used with the starters of large AC motors is to provide _____________. A. increased voltage for starting B. increased torque for starting C. reduced voltage for starting D. speed control

Description : The function of the autotransformers used with the starters of large AC motors is to provide _____________. A. increased voltage for starting B. increased torque for starting C. reduced voltage for starting D. speed control

Last Answer : Answer: C

A two-winding single phase transformer has a voltage regulation of 4.5% at full-load and unity power-factor. At full-load and 0.80 power-factor lagging load the voltage regulation will be (A) 4.5%. (B) less than 4.5%. (C) more than 4.5%. (D) 4.5% or more than 4.5%.

Description : A two-winding single phase transformer has a voltage regulation of 4.5% at full-load and unity power-factor. At full-load and 0.80 power-factor lagging load the voltage regulation will be (A) 4.5%. (B) less than 4.5%. (C) more than 4.5%. (D) 4.5% or more than 4.5%.

Last Answer : (C) more than 4.5%.

In transformers, why the low voltage winding is placed near the core?

Description : In transformers, why the low voltage winding is placed near the core?

Last Answer : The winding & Core are both made of metals and so an insulation have to be placed in between them, the thickness of insulation depends on the voltage rating of the winding. In order to reduce the insulation requirement the low voltage winding place near the core.

Which of the following statements identifies the difference between the primary windings and the secondary windings of a 2:1 stepdown transformer? A. The secondary windings have twice as much resistance as the primary windings. B. The secondary windings give off twice as much heat as the primary windings. C. The secondary windings require half as much current as the primary windings. D. The secondary windings have half as many turns as the primary windings.

Description : Which of the following statements identifies the difference between the primary windings and the secondary windings of a 2:1 stepdown transformer? A. The secondary windings have twice as much resistance ... primary windings. D. The secondary windings have half as many turns as the primary windings.

Last Answer : Answer: D

The purpose of the automatic bus transfer shown in the illustration is to ___________. EL-0014 A. stepdown voltage to the lighting distribution panel B. provide emergency power to the lighting distribution panel C. energize the emergency switchboard from the main switchboard D. provide overcurrent protection to the lighting distribution panel

Description : The purpose of the automatic bus transfer shown in the illustration is to ___________. EL-0014 A. stepdown voltage to the lighting distribution panel B. provide emergency power to ... emergency switchboard from the main switchboard D. provide overcurrent protection to the lighting distribution panel

Last Answer : Answer: B

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

Why we need isolation transformers in power circuit ? why cant we use breakers to isolate?

Description : Why we need isolation transformers in power circuit ? why cant we use breakers to isolate?

Last Answer : In Isolation transformer is used, if there is change in parameter values of any side, the other side parameters will remain unchanged.

What are isolation transformers?

Description : What are isolation transformers?

Last Answer : In this type of transformer the primary and secondary are same. When it is required to isolate the primary and secondary circuits these type of transformers are used. It protects the circuits connected in secondary side when major fault occurs in primary side.

The stepup transformer increases?

Description : The stepup transformer increases?

Last Answer : The stepup transformer increases voltage.

Ships’ generators produce 450-volt, three-phase, ac power; however, most equipment uses 117-volt, single-phase power What transformers and connections are used to convert 450- volt, threephase power to 117-volt, single-phase power?

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Last Answer : A method of generating oscillations, a method of turning the oscillations on and off (keying), and an antenna to radiate the energy.

When a transformer is used to step down voltage, the low voltage winding is _____________. A. part of the core B. the primary coil C. not insulated D. the secondary coil

Description : When a transformer is used to step down voltage, the low voltage winding is _____________. A. part of the core B. the primary coil C. not insulated D. the secondary coil

Last Answer : Answer: D

What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?

Description : What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?

Last Answer : 1.Direct loading test 2.Open circuit test 3. Short circuit test 4. Sumpner's or back to back test

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Last Answer : (C) 3.0 V.

A two -winding single phase transformer has a voltage regulation of 4.5% at full - load and unity power ...

Description : A two -winding single phase transformer has a voltage regulation of 4.5% at full - load and unity power -factor. At full -load and 0.80 lagging power-factor, the voltage regulation will be: (A) 4.5% (B) less than 4.5% (C) more than 4.5% (D) none of the above

Last Answer : A two -winding single phase transformer has a voltage regulation of 4.5% at full - load and unity power -factor. At full -load and 0.80 lagging power-factor, the voltage regulation will be: more than 4.5%

A 220/440 V, 50 Hz, 5 KVA, single phase transformer operates on 220V, 40Hz supply with secondary winding open circuited. Then (A) Both eddy current and hysteresis losses decreases. (B) Both eddy current and hysteresis losses increases. (C) Eddy current loss remains the same but hysteresis loss increases. (D) Eddy current loss increases but hysteresis loss remains the same.

Description : A 220/440 V, 50 Hz, 5 KVA, single phase transformer operates on 220V, 40Hz supply with secondary winding open circuited. Then (A) Both eddy current and hysteresis losses decreases. (B) Both ... same but hysteresis loss increases. (D) Eddy current loss increases but hysteresis loss remains the same.

Last Answer : (A) Both eddy current and hysteresis losses decreases.

Routine maintenance of dry-type transformers should include ____________. A. cleaning the windings, if accessible, with a vacuum cleaner or very low pressure air B. measuring and recording the winding temperature with an accurate mercury thermometer C. periodic cleaning of the winding insulation with an approved solvent D. making sure that the units are close to bulkheads or corners to protect them from damage

Description : Routine maintenance of dry-type transformers should include ____________. A. cleaning the windings, if accessible, with a vacuum cleaner or very low pressure air B. measuring and recording the winding ... . making sure that the units are close to bulkheads or corners to protect them from damage

Last Answer : Answer: A

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Description : What is the Difference Between "Insulating", "Isolating", and "Shielded Winding" Transformers?

Last Answer : Insulating and Isolating transformers are identical. These terms are used to describe the isolation of the primary and secondary windings, or insulation between the two. A shielded winding transformer, ... are connected to each other electrically, are not of the insulating or isolating variety.

How the starting winding produce rotation in a single phase resistance start induction motor?

Description : How the starting winding produce rotation in a single phase resistance start induction motor?

Last Answer : The starting winding is highly resistive and the main winding is inductive. So the phase difference between the two currents becomes nearly 90 degree and hence the motor start as two phase motor.

If all three ground-detection lamps continue to burn at equal intensity after the test button is depressed and released, which of the listed conditions is indicated? A. No grounds exist B. All three phases are grounded C. The test switch is faulty D. The current transformers are shorted out

Description : If all three ground-detection lamps continue to burn at equal intensity after the test button is depressed and released, which of the listed conditions is indicated? A. No grounds exist B. All three phases are grounded C. The test switch is faulty D. The current transformers are shorted out

Last Answer : Answer: A

On a switchboard, if all three ground detection lamps remain burning at half intensity when the test button is depressed, which of the listed conditions is indicated? A. No grounds exist. B. All three phases are grounded. C. The test switch is grounded. D. The current transformers are shorted.

Description : On a switchboard, if all three ground detection lamps remain burning at half intensity when the test button is depressed, which of the listed conditions is indicated? A. No grounds exist. B. All three phases are grounded. C. The test switch is grounded. D. The current transformers are shorted.

Last Answer : Answer: A

The winch shown in the illustration operates in any of the positions with the master switch in the 'lower' direction, but will not 'hoist' in any of the master switch hoist positions. Which of the listed faults could be the cause? EL-0102 A. Master switch contact 'MS3' may have defective springs. B. Contactor '3M' coil could have an open winding. C. Contact '2M' in the power circuit may be badly corroded. D. Series relay 'FR' may be open.

Description : The winch shown in the illustration operates in any of the positions with the master switch in the 'lower' direction, but will not 'hoist' in any of the master switch hoist positions. Which of the listed faults ... '2M' in the power circuit may be badly corroded. D. Series relay 'FR' may be open.

Last Answer : Answer: A

Which of the listed types of motor controllers and starters is illustrated? EL-0080 A. Across-the-line B. Primary-resistor C. Autotransformer D. Part-winding

Description : Which of the listed types of motor controllers and starters is illustrated? EL-0080 A. Across-the-line B. Primary-resistor C. Autotransformer D. Part-winding

Last Answer : Answer: C

As shown in the illustration, which of the listed types of motor controllers and starters is indicated? EL-0012 A. Across-the-line B. Capacitor C. Autotransformer D. Part-winding

Description : As shown in the illustration, which of the listed types of motor controllers and starters is indicated? EL-0012 A. Across-the-line B. Capacitor C. Autotransformer D. Part-winding

Last Answer : Answer: C

The main purpose of the auxiliary winding on a split-phase, single-phase motor is to _____________. A. limit the starting voltage B. increase the starting current C. start the motor D. keep the motor running in the event the main winding should fail

Description : The main purpose of the auxiliary winding on a split-phase, single-phase motor is to _____________. A. limit the starting voltage B. increase the starting current C. start the motor D. keep the motor running in the event the main winding should fail

Last Answer : Answer: C

The electrical diagram shown in the illustration is used to depict a/an ____________. EL-0015 A. resistance circuit B. inductive circuit C. stepdown circuit D. capacitive circuit

Description : The electrical diagram shown in the illustration is used to depict a/an ____________. EL-0015 A. resistance circuit B. inductive circuit C. stepdown circuit D. capacitive circuit

Last Answer : Answer: D

What is an isolation transformer?

Description : What is an isolation transformer?

Last Answer : A. An isolation transformer also referred to as insulating transformer, is one where the primary and secondary windings are separate.

Why lighting isolation transformer is req.?

Description : Why lighting isolation transformer is req.? 

Last Answer : a) 3 wire to 4 wire conversion, since neutral is required for lighting load. b) Prevents transfer of E/F currents c) Reduces the fault level on secondary side and permits use of small sized cables / CB’s / fuses.

A selectable marker is used to (a) help in eliminating the non-transformants, so that the transformants can be regenerated (b) identify the gene for a desired trait in an alien organism (c) select a suitable vector for transformation in a specific crop (d) mark a gene on a chromosome for isolation using restriction enzyme.

Description : A selectable marker is used to (a) help in eliminating the non-transformants, so that the transformants can be regenerated (b) identify the gene for a desired trait in an alien organism (c) ... in a specific crop (d) mark a gene on a chromosome for isolation using restriction enzyme.

Last Answer : (a) help in eliminating the non-transformants, so that the transformants can be regenerated

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.

Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.

Description : Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.

Last Answer : 1) Voltage ratio: The voltages in primary and secondary winding is proportional to number of turns in primary and secondary respectively. So, the voltage ratio is same as transformation ratio. V2/V1 = N2 ... as transformation ratio of transformer. It is denoted by K. K = N2/N1

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

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.

In the illustrated electronic governor, the circuit card connected to the potential and current transformers is for ________. EL-0046 A. increasing the signal strength to the governor to maintain constant engine speed with increased load B. send a kilowatt signal to the metering circuit C. shutting down the prime mover in the event of reverse power to protect from motorization D. conditioning the load through the use of a magnetic amplifier current transformer

Description : In the illustrated electronic governor, the circuit card connected to the potential and current transformers is for ________. EL-0046 A. increasing the signal strength to the governor to ... from motorization D. conditioning the load through the use of a magnetic amplifier current transformer

Last Answer : Answer: A

What are the advantages of shell type transformer over core type transformers?

Description : What are the advantages of shell type transformer over core type transformers?

Last Answer : In shell type transformers the coils are well supported on the all sides and so they can withstand higher mechanical stresses developed during short circuit conditions. Also the leakage reactance will be less in shell type transformers.

In conversion of 3-phase to 2-phase supply with T connection, the transformation ratio of the teaser will be__ times to that of main transformer: a) 1.732 b) 1.15 c) 0.866 d) Unity

Description : In conversion of 3-phase to 2-phase supply with T connection, the transformation ratio of the teaser will be__ times to that of main transformer: a) 1.732 b) 1.15 c) 0.866 d) Unity

Last Answer : Ans: C

What is the transformation ratio in transformer?

Description : What is the transformation ratio in transformer?

Last Answer : Equation for transformation ratio is, E2/E1 = N2/N1 = k k = >1 in step up transformer, where secondary turns are more and thus voltage is more to reduce the transmission current. k =

A three-phase transformer, connected in star-delta, is composed of three single-phase transformers, each

Description : A three-phase transformer, connected in star-delta, is composed of three single-phase transformers, each rated 127/ 13.2 kV. The line-to-line voltage ratio for the three-phase transformer is: A) 220 / 13.2 kV B) 127 / 13.2 kV C) 127 / 220 kV D) 220 / 220 kV

Last Answer : A three-phase transformer, connected in star-delta, is composed of three single-phase transformers, each rated 127/ 13.2 kV. The line-to-line voltage ratio for the three-phase transformer is: 220 / 13.2 kV 

(a) Define permeability. (b) Define MMF. (c) Define form factor of an alternating quantity. (d) Define frequency and time period of an alternating quality. (e) Define transformation ratio of transformer. (f) State the EMF equation of a 1 transformer and state the meaning of each term used. (g) Give two applications of single phase motors.

Description : (a) Define permeability. (b) Define MMF. (c) Define form factor of an alternating quantity. (d) Define frequency and time period of an alternating quality. (e) Define transformation ratio of transformer. ... and state the meaning of each term used. (g) Give two applications of single phase motors. 

Last Answer : Permeability : It is the ability of a magnetic/Non magnetic material to allow setting up of flux in it.  MMF : The magneto motive force (MMF) is the force required to setup flux in a magnetic / ... applications of single phase motors : Water pumps, ceiling fan, lathe machine

If a 120v transformer has 200 turns the secondary winding has 20 turns what is the secondary winding voltage?

Description : If a 120v transformer has 200 turns the secondary winding has 20 turns what is the secondary winding voltage?

Last Answer : 12v

What is the secondary winding voltage if a 120v transformer has 200 turns the secondary winding has 20 turns?

Description : What is the secondary winding voltage if a 120v transformer has 200 turns the secondary winding has 20 turns?

Last Answer : 12 volts

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

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

Last Answer : (d) impulse voltage