An auto transformer is preferred over an ordinary two winding transformer due to: a) Safety of operation b) Availability of taps on secondary c) Copper savings d) All the above

An auto transformer is preferred over an ordinary two winding transformer due to:   a) Safety of operation b) Availability of taps on secondary c) Copper savings d) All the above
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7 The main advantage of auto transformer over a two winding transformer is A. Hysteresis losses are reduced B. Saving in winding material C. Copper losses are negligible D. Eddy losses are totally eliminated

Description : 7 The main advantage of auto transformer over a two winding transformer is A. Hysteresis losses are reduced B. Saving in winding material C. Copper losses are negligible D. Eddy losses are totally eliminated

Last Answer : A) hysteresis losses is reduced

21.The ordinary two winding transformer's primary and secondary windings always have A. different no of turns B. same size of copper wire C. a common magnetic circuit D. separate magnetic circuits

Description : 21.The ordinary two winding transformer's primary and secondary windings always have A. different no of turns B. same size of copper wire C. a common magnetic circuit D. separate magnetic circuits

Last Answer : C. A common magnetic circuit

The hook-on AC volt-ammeter consists essentially of a split-core and a rectifiertype instrument connected to the secondary winding of a _____________. A. potential transformer B. control transformer C. current transformer D. reactance transformer

Description : The hook-on AC volt-ammeter consists essentially of a split-core and a rectifiertype instrument connected to the secondary winding of a _____________. A. potential transformer B. control transformer C. current transformer D. reactance transformer

Last Answer : Answer: C

Relative to the secondary winding of a step-up transformer, the primary winding will have _____________. A. more turns B. fewer turns C. half as many turns D. twice as many turns

Description : Relative to the secondary winding of a step-up transformer, the primary winding will have _____________. A. more turns B. fewer turns C. half as many turns D. twice as many turns

Last Answer : Answer: B

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

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.

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.

The turns ratio of transformer 'A' shown in the illustration is four to one and all taps are evenly spaced. If 120 volts were applied to terminals 'H1' and 'H3', what would appear at 'X1' and 'X2'? EL-0082 A. 15 volts B. 30 volts C. 480 volts D. 960 volts

Description : The turns ratio of transformer 'A' shown in the illustration is four to one and all taps are evenly spaced. If 120 volts were applied to terminals 'H1' and 'H3', what would appear at 'X1' and 'X2'? EL-0082 A. 15 volts B. 30 volts C. 480 volts D. 960 volts

Last Answer : Answer: A

What is the purpose of providing Taps in transformer and where these are provided?

Description : What is the purpose of providing Taps in transformer and where these are provided?

Last Answer : In order to attain the required voltage, taps are provided, normally at high voltages side(low current).

Why is short pitch winding preferred over full-pitch winding ?

Description : Why is short pitch winding preferred over full-pitch winding ?

Last Answer : Advantages · Sinusoidal waveform: Waveform of the emf can be approximately made to a sine wave and distorting harmonics can be reduced or totally eliminated. · Economical :Conductor ... harmonics are eliminated, the eddy current and hysteresis losses are reduced which increases overall efficiency

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

In replacing a defective transformer with a new one, which of the following actions must be carried out to insure proper operation of the equipment it serves? A. The secondary leads must be grounded for 10 minutes to remove static charges. B. The transformer connections must be made as before with regard to the indicated polarity. C. The iron core of the transformer must be flashed to pre-magnetize it. D. The iron core must be grounded for 10 minutes to remove any residual magnetism.

Description : In replacing a defective transformer with a new one, which of the following actions must be carried out to insure proper operation of the equipment it serves? A. The secondary leads must be grounded ... magnetize it. D. The iron core must be grounded for 10 minutes to remove any residual magnetism.

Last Answer : Answer: B

Compare auto transformer with two winding transformer.

Description : Compare auto transformer with two winding transformer.

Last Answer : Autotransformer and Two winding transformer

A 400V/100 V, 10 KVA two-winding transformer is reconnected as an auto-transformer across a suitable

Description : A 400V/100 V, 10 KVA two-winding transformer is reconnected as an auto-transformer across a suitable voltage source. The maximum rating of such an arrangement could be  A) 50 KVA B) 15 KVA C) 12.5 KVA D) 8.75 KVA

Last Answer : A 400V/100 V, 10 KVA two-winding transformer is reconnected as an auto-transformer across a suitable voltage source. The maximum rating of such an arrangement could be 50 KVA

The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Description : The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Last Answer : Ans: A

An Auto-transformer (which has only one winding) may be used as a ______ .

Description : An Auto-transformer (which has only one winding) may be used as a ______ .  (A) Both Step-Up and Step-Down transformer (B) Step-Down Transformer (C) Step-Up Transformer (D) None of these

Last Answer : An auto-transformer may be used as: A. Both Step-Up and Step-Down transformer An auto-transformer is a type of transformer that has only one winding and can be used as a step-up or ... size. Therefore, an auto-transformer is a versatile transformer that can be used for a variety of applications.

Which type of winding is preferred for armature windings of alternator? Why?

Description : Which type of winding is preferred for armature windings of alternator? Why?

Last Answer : Double layer, short pitched and distributed type of armature winding. It eliminates high frequency harmonics hence it makes induced emf more sinusoidal.

28.In a two winding transformer, the emf /turn in secondary winding is always......the induced emf power turn in primary A. equal to k times B. equal to 1/k times C. equal D. greater than

Description : 28.In a two winding transformer, the emf /turn in secondary winding is always......the induced emf power turn in primary A. equal to k times B. equal to 1/k times C. equal D. greater than

Last Answer : C. equal

6 In a two winding transformer, the primary and secondary induced emf E1 & E2 are always A. equal in magnitude B. anti phase with each other C. in phase with each other D. determined by load on transformer secondary

Description : 6 In a two winding transformer, the primary and secondary induced emf E1 & E2 are always A. equal in magnitude B. anti phase with each other C. in phase with each other D. determined by load on transformer secondary

Last Answer : C. In phase with each other

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

What causes a voltage to be developed across the secondary winding of a transformer?

Description : What causes a voltage to be developed across the secondary winding of a transformer?

Last Answer : The magnetic lines generated by the current in the primary cut

In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above

Description : In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above

Last Answer : (b) secondary winding

12] Which is not the basic element of the transformer? A. core B. primary winding C. secondary winding D. mutual flux

Description : 12] Which is not the basic element of the transformer? A. core B. primary winding C. secondary winding D. mutual flux

Last Answer : D. Mutual flux

The doorbell on your house requires a 12 volt alternating current. A transformer having a primary winding of 1,600 turns is to be used to step down your house's 110-volt alternating current. How many turns are there on the secondary winding?

Description : The doorbell on your house requires a 12 volt alternating current. A transformer having a primary winding of 1,600 turns is to be used to step down your house's 110-volt alternating current. How many turns are there on the secondary winding?

Last Answer : ANSWER: 175 TURNS 

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary

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 : 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 3.0 V.

A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary

Description : A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is? A.0.2 B.0.4 C.5 D.25

Last Answer : A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is? A.0.2 B.0.4 C.5 D.25

If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding,

Description : If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding, what is the reflective resistance if the secondary load resistance is 250 ohms? A.250 ohms B.25 ohms C.6,250 ohms D.62,500 ohms

Last Answer : 6,250 ohms

A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts

Description : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary?  (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts

Last Answer : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary?  (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts

If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding...

Description : If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding open circuited: (A) both the eddy current and the hysteresis losses will decrease ... losses will increase (D) eddy current losses will increase but the hysteresis losses will remain the same

Last Answer : If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding open circuited: both the eddy current and the hysteresis losses will decrease

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary ...

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 (B) 2.5 V (C) 3.0 V (D) 6.0 V

Last Answer : 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: 3.0 V

A CT has 2 – secondary windings. If we use only one secondary winding can we keep the unused secondary winding short circuited?

Description : A CT has 2 – secondary windings. If we use only one secondary winding can we keep the unused secondary winding short circuited?

Last Answer : No. If it is short-circuited then the ratio will not get correctly. The turns of primary winding will be shared between 2 secondary windings. So the unused secondary winding should kept open. 

What is Two winding transformer?

Description : What is Two winding transformer?

Last Answer : Two separate windings one as primary and other as secondary are used. Both windings are magnetically coupled.

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%.

Booster transformer should never: a) Have fuse in the HV winding b) Be left open circuited c) Be left closed circuited d) None of the above

Description : Booster transformer should never: a) Have fuse in the HV winding b) Be left open circuited c) Be left closed circuited d) None of the above

Last Answer : Ans: B

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

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

Last Answer : Answer: C

What is tertiary winding? What is Three Winding Transformer? What are its advantages?

Description : What is tertiary winding? What is Three Winding Transformer? What are its advantages?

Last Answer : A. In some high rating transformers, one winding, in addition to the primary and secondary winding, is used. This is known as Tertiary Winding of Transformer. Because of this third winding, the ... it assists in limitation of fault current in the event of a short circuit from line to neutral.

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

What is Six winding transformer?

Description : What is Six winding transformer?

Last Answer : Three windings in primary and three windings in secondary are used, They are three phase transformers.They are connected in either star-star, delta-delta, star delta or delta star.

What is Three winding transformer?

Description : What is Three winding transformer?

Last Answer : Three windings are used each work as primary and secondary. Also primary and secondary windings are conductively couple. They are three phase auto transformer

If the centrifugal switch or relay used for cutting out the starting winding of a split-phase induction motor fails to open once the motor is in operation, the _____________. A. motor will overspeed B. starting winding will burn out C. motor will immediately stall under load D. motor torque will be above normal at rated speed

Description : If the centrifugal switch or relay used for cutting out the starting winding of a split-phase induction motor fails to open once the motor is in operation, the _____________. A. motor will overspeed B ... C. motor will immediately stall under load D. motor torque will be above normal at rated speed

Last Answer : Answer: B

Which of the following problems will most likely occur if the starting winding of a split-phase induction motor failed to cutout once the motor was in continuous operation? A. The motor will overspeed. B. The motor will run at a reduced speed. C. A time delay will stop the motor. D. The winding will burn out.

Description : Which of the following problems will most likely occur if the starting winding of a split-phase induction motor failed to cutout once the motor was in continuous operation? A. The motor will overspeed. B. The ... reduced speed. C. A time delay will stop the motor. D. The winding will burn out.

Last Answer : Answer: D

Which of the following losses is/are present in every direct current generator armature? A. Winding copper loss B. Core eddy current loss C. Magnetic hysteresis loss D. All of the above.

Description : Which of the following losses is/are present in every direct current generator armature? A. Winding copper loss B. Core eddy current loss C. Magnetic hysteresis loss D. All of the above.

Last Answer : Answer: D

Pick out the wrong statement. (A) Packed towers are preferred for vacuum operation, because the pressure drop through the packing is less and they (packings) also lessen the possibility of tower wall collapse (B) Packed towers are preferred over plate towers for handling corrosive and foamy liquids (C) Diameter of randomly packed tower is normally more than 1.2 metres (D) Due to uneven supply and improper distribution of liquid, problem of channelling, loading & flooding is generally encountered in packed towers

Description : Pick out the wrong statement. (A) Packed towers are preferred for vacuum operation, because the pressure drop through the packing is less and they (packings) also lessen the ... of liquid, problem of channelling, loading & flooding is generally encountered in packed towers

Last Answer : (C) Diameter of randomly packed tower is normally more than 1.2 metres

Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is?

Description : Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is?

Last Answer : Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is approximately equal to 1.

Heavy water is preferred over ordinary water as a coolant, because it. (A) Acts both as an efficient coolant as well as a moderator (B) Can be heated to a higher temperature without pressurizing (C) Is less prone to radiation damage (D) All (A), (B) and (C)

Description : Heavy water is preferred over ordinary water as a coolant, because it. (A) Acts both as an efficient coolant as well as a moderator (B) Can be heated to a higher temperature without pressurizing (C) Is less prone to radiation damage (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

A FET is preferred over an ordinary transistor because it

Description : A FET is preferred over an ordinary transistor because it  1. Permits high degree of isolation between input & output circuits 2. Has low noise level 3. Has very high power gain 4. Has all the above properties 

Last Answer : A FET is preferred over an ordinary transistor because it Has all the above properties 

The turns ratio of transforme 'A' shown in the illustration is four to one and all taps are evenly spaced. If 110 volts were applied to terminals 'X1' and 'X3', what would be indicated across 'H1' and 'H2'? EL-0082 A. 37.5 volts B. 55 volts C. 220 volts D. 440 volts

Description : The turns ratio of transforme 'A' shown in the illustration is four to one and all taps are evenly spaced. If 110 volts were applied to terminals 'X1' and 'X3', what would be indicated across 'H1' and 'H2'? EL-0082 A. 37.5 volts B. 55 volts C. 220 volts D. 440 volts

Last Answer : Answer: C

The turns ratio of device 'A' shown in the illustration is four to one and all taps are evenly spaced. If 110 volts were applied to terminals 'X1' and 'X3', what would be indicated across 'H1' and 'H2'? EL-0082 A. 37.5 volts B. 55 volts C. 220 volts D. 440 volts

Description : The turns ratio of device 'A' shown in the illustration is four to one and all taps are evenly spaced. If 110 volts were applied to terminals 'X1' and 'X3', what would be indicated across 'H1' and 'H2'? EL-0082 A. 37.5 volts B. 55 volts C. 220 volts D. 440 volts

Last Answer : Answer: C

The turns ratio of device 'A' shown in the illustration is four to one and all taps are evenly spaced. If 120 volts were applied to terminals 'H1' and 'H3', what would appear at 'X1' and 'X2'? EL-0082 A. 15 volts B. 30 volts C. 480 volts D. 960 volts

Description : The turns ratio of device 'A' shown in the illustration is four to one and all taps are evenly spaced. If 120 volts were applied to terminals 'H1' and 'H3', what would appear at 'X1' and 'X2'? EL-0082 A. 15 volts B. 30 volts C. 480 volts D. 960 volts

Last Answer : Answer: A