Transformer Parallel Operation Why To do Is it

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Transformer Rated Load Wait More Load Power For Supply To do Is.
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What are the conditions for parallel operation of transformer?

Description : What are the conditions for parallel operation of transformer?

Last Answer : -Equal polarity -Equal turn ratio -percentage impedance should be same -Equal X/R ratio -Equal KVA rating -Equal phase sequence

What is the need for parallel operation of transformer?

Description : What is the need for parallel operation of transformer?

Last Answer : -Non availability of single large transformer to meet the load -Increased power demand -To improve reliability -If many smaller transformer is used one can be used as spare -Transportation problem for large transformer.

State any two conditions for parallel operation of 3-phase transformer.

Description : State any two conditions for parallel operation of 3-phase transformer.

Last Answer : Conditions for Parallel operation of 3 phase transformer 1) Voltage ratings of both the transformers must be identical. 2) Percentage or p.u. impedance should be equal in magnitude. 3) X/R ratio ... between primary & secondary voltages must be same. 6) Phase sequence on both sides must be same.

Explain parallel operation of transformer in context of energy conservation.

Description : Explain parallel operation of transformer in context of energy conservation.

Last Answer : Parallel operation of the transformer in context of energy conservation: The transformers operate near their maximum efficiency around 70 % to 100 % of their rated loads. For huge establishments drawing highly ... thus saving its low load losses. This is done as per the requirements of the loads.

List the conditions for parallel operation of three phase transformer.

Description : List the conditions for parallel operation of three phase transformer.

Last Answer : Conditions for Parallel operation of 3 phase transformer: 1) Voltage ratings of both the transformers must be identical. 2) Percentage / p.u. impedances should be equal in magnitude. 3) X/R ratio of ... between primary & secondary voltages must be same. 6) Phase sequence of both must be same.

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

Description : 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

Last Answer : Ans: C

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

How does change in frequency affect the operation of a given transformer?

Description : How does change in frequency affect the operation of a given transformer?

Last Answer : a) Iron loss .........increases with a decrease in frequency. A 60-Hz transformer will have nearly 11% higher losses when worked on 50Hz instead of 60 Hz. However, when a 25-Hz ... ....since total loss is greater at a lower frequency, the temperature is increased with decrease in frequency.

Explain the operation of variable frequency transformer?

Description : Explain the operation of variable frequency transformer?

Last Answer : A. A variable frequency transformer is used to transmit electricity between two asynchronous alternating current domains. It is a double fed electric machine resembling a vertical shaft hydroelectric ... adjustable phase shifting transformer. It allows control of the power flow between two networks.

How does change in frequency affect the operation of a given transformer?

Description : How does change in frequency affect the operation of a given transformer?

Last Answer : With a change in frequency, iron and copper loss, regulation, efficiency & heating varies so the operation of transformer is highly affected.

Comment on the working principle of operation of a single-phase transformer.

Description : Comment on the working principle of operation of a single-phase transformer.

Last Answer : Working principle of operation of a single-phase transformer can be explained as An AC supply passes through the primary winding, a current will start flowing in the primary winding. As ... is known as mutually induced voltage. Hence, transformer works on the principle of electromagnetic induction.

What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to

Description : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... Current will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

Last Answer : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

To prevent mal-operation of differentially connected relay while energizing a transformer, the relay

Description : To prevent mal-operation of differentially connected relay while energizing a transformer, the relay restraining coil is based with  (1) second harmonic current  (2) third harmonic current  (3) fifth harmonic current  (4) seventh harmonic current

Last Answer : To prevent mal-operation of differentially connected relay while energizing a transformer, the relay restraining coil is based with  second harmonic current 

What is the basic principle of operation of a transformer?

Description : What is the basic principle of operation of a transformer?  (A) Self-induction (B) Mutual-induction (C) Static-induction (D) Dynamic-induction 

Last Answer : B.  Transformer works on principle of MUTUAL INDUCTION. When voltage is applied to the primary winding of the transformer, current flows through the current called magnetising current results in ... . Thus power flow from primary to secondary circuit is simply based on the mutual induction.

What will happen if transformer in parallel connection have different phase sequence ?

Description : What will happen if transformer in parallel connection have different phase sequence ?

Last Answer : If the phase sequence is in an incorrect manner, in every cycle each pair of phases will get short-circuited.

What will happen if transformer in parallel connection have different percentage impedance or X/R ratio ?

Description : What will happen if transformer in parallel connection have different percentage impedance or X/R ratio ?

Last Answer : A difference in the ratio of the reactance value to resistance value of the per unit impedance results in a different phase angle of the currents carried by the two paralleled transformers; one ... of the combined output. Hence, the real power will not be proportionally shared by the transformers.

What will happen if transformer in parallel connection have different voltage ratio?

Description : What will happen if transformer in parallel connection have different voltage ratio?

Last Answer : Two transformers in Parallel should have the same primary and secondary voltage ratings. Any error in the voltage ratio would cause heavy circulating currents to flow between the transformers. ... in overloading of one transformer. This circulating current will result in increased copper losses.

What will happen if transformer in parallel connection have opposite polarity?

Description : What will happen if transformer in parallel connection have opposite polarity?

Last Answer : Connecting transformers with wrong polarity can result in circulating currents or short circuits

What type of balun (balanced-to-unbalanced) is used in high frequency applications? A. Transformer type balun B. A specially configured coaxial transmission line C. A specially configured parallel-wire line D. A λ/2 transformer balun

Description : What type of balun (balanced-to-unbalanced) is used in high frequency applications? A. Transformer type balun B. A specially configured coaxial transmission line C. A specially configured parallel-wire line D. A λ/2 transformer balun

Last Answer : B. A specially configured coaxial transmission line

To couple a coaxial line to parallel line, it is better to use a ______. A. Slotted line B. Quarter-wave transformer C. Directional Coupler D. Balun

Description : To couple a coaxial line to parallel line, it is better to use a ______. A. Slotted line B. Quarter-wave transformer C. Directional Coupler D. Balun

Last Answer : D. Balun

To connect coaxial line to a parallel-wire _________ is the best to use. A. directional coupler B. quarter-wave transformer C. balun D. slotted line

Description : To connect coaxial line to a parallel-wire _________ is the best to use. A. directional coupler B. quarter-wave transformer C. balun D. slotted line

Last Answer : C. balun

To couple a coaxialline toa parallel-wire line,itisbesttouse a a. slotted line b.balun c. directional coupler d. quarter-wave transformer

Description : To couple a coaxialline toa parallel-wire line,itisbesttouse a a. slotted line b.balun c. directional coupler d. quarter-wave transformer

Last Answer : b.balun

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

Coast Guard Regulations (46 CFR) require that each alternating current generator arranged for parallel operation shall be provided with _____________. A. more than one means of excitation B. individual circuit fuses C. a high back-pressure trip D. a reverse-power trip

Description : Coast Guard Regulations (46 CFR) require that each alternating current generator arranged for parallel operation shall be provided with _____________. A. more than one means of excitation B. individual circuit fuses C. a high back-pressure trip D. a reverse-power trip

Last Answer : Answer: D

Which of the following statements is true concerning the operation of two alternators in parallel? A. The cycles per second of each alternator are the same. B. Both alternator governors must be set with the same amount of speed droop. C. The number of field poles must be the same on each alternator. D. The load must always be divided equally between alternators.

Description : Which of the following statements is true concerning the operation of two alternators in parallel? A. The cycles per second of each alternator are the same. B. Both alternator governors must be set ... be the same on each alternator. D. The load must always be divided equally between alternators.

Last Answer : Answer: A

A vessel is equipped with two ship's service generators. Generator #1 is rated at 900 kw and generator #2 is rated at 600 kw. During parallel operation, with a hotel load of 1,000 kw, what should be the kw load on generator #2? A. 100 kw B. 400 kw C. 500 kw D. 600 kw

Description : A vessel is equipped with two ship's service generators. Generator #1 is rated at 900 kw and generator #2 is rated at 600 kw. During parallel operation, with a hotel load of 1,000 kw, what should be the kw load on generator #2? A. 100 kw B. 400 kw C. 500 kw D. 600 kw

Last Answer : Answer: B

Which of the following should be the FIRST step in removing a generator from parallel operation? A. Trip the generator off the switchboard. B. Turn off all electrical equipment. C. Remove the load from the 'off going' generator. D. Increase the cycles of the generator staying on the line.

Description : Which of the following should be the FIRST step in removing a generator from parallel operation? A. Trip the generator off the switchboard. B. Turn off all electrical equipment. C. Remove the load from the 'off going' generator. D. Increase the cycles of the generator staying on the line.

Last Answer : Answer: C

In the illustration, the contacts between terminals 26 and 27 should be closed when _________. EL-0046 A. using one generator in isochronous mode only B. using two or more generators in parallel only C. the prime mover speed is to remain constant through varying loads in parallel or single operation D. the circuit breaker is closed for that generator

Description : In the illustration, the contacts between terminals 26 and 27 should be closed when _________. EL-0046 A. using one generator in isochronous mode only B. using two or more generators in ... through varying loads in parallel or single operation D. the circuit breaker is closed for that generator

Last Answer : Answer: C

What are the conditions for parallel operation of two transformers ?

Description : What are the conditions for parallel operation of two transformers ?

Last Answer : Transformers which are to be operated parallel should have to satisfy the following conditions: Polarities of both the transformers should be same else lead to short circuit Voltage rating of ... Phase displacement of transformers should be same Phase sequence of two transformers should be same

What are the conditions for parallel operation of two transformers ?

Description : What are the conditions for parallel operation of two transformers ?

Last Answer : Transformers which are to be operated parallel should have to satisfy the following conditions: Polarities of both the transformers should be same else lead to short circuit Voltage rating of ... Phase displacement of transformers should be same Phase sequence of two transformers should be same

What are the Conditions for parallel operation of transformers?

Description : What are the Conditions for parallel operation of transformers?

Last Answer : A. a) Same voltage ratio of transformer: If two transformers of different voltage ratio, are connected in parallel with same primary supply voltage, there will be a difference in secondary voltages. If ... not in same phase sequence, during the cycle, each pair of phases will be short circuited.

What are the advantages of parallel operation of transformers?

Description : What are the advantages of parallel operation of transformers?

Last Answer : A. 1) To maximize electrical power system efficiency: Generally electrical power transformer gives the maximum efficiency at full load. If we run numbers of transformers in parallel, we can switch ... running in parallel can be removed from system to balance the capital investment and its return.

What Are The Conditions To Be Satisfied For Parallel Operation Of Dc Generators?

Description : What Are The Conditions To Be Satisfied For Parallel Operation Of Dc Generators?

Last Answer : The polarities of the generators must be same or the connections must be interchanged till they become same. The voltages of both the generators must be equal. The change of voltage with ... and negative terminals of generators must be connected properly to the positive and negative of busbar.

What steps are to be taken before disconnecting one Alternator from parallel operation?

Description : What steps are to be taken before disconnecting one Alternator from parallel operation?

Last Answer : The following steps are to be taken before disconnecting one Alternator from parallel operation · The prime-mover input of the outgoing generator has to be decreased and that of other generators ... delivered by the outgoing generator is zero, it has to be disconnected from parallel operation.

What is need of parallel operation of alternators?

Description : What is need of parallel operation of alternators?

Last Answer : 1. Optimum utilization of alternators as most of the power stations are interconnected by grid. 2. Reduced operating cost: number of alternators operating at a time can be changed depending on ... demands. 3. Easy maintenance: Alternator may be shut down for maintenance 4. Continuity and reliability

During unit operation, can we parallel UT & SUT continuously?

Description : During unit operation, can we parallel UT & SUT continuously?

Last Answer : No, due to switchgear limitation.  

During unit operation, can we parallel 2 SUT?

Description : During unit operation, can we parallel 2 SUT? 

Last Answer : No, due to switchgear limitation. 

The operation of revolving a plane table about its vertical axis so that all lines on the sheet become parallel to corresponding lines on the ground, is known (A) Levelling (B) Centering (C) Orientation (D) Setting

Description : The operation of revolving a plane table about its vertical axis so that all lines on the sheet become parallel to corresponding lines on the ground, is known (A) Levelling (B) Centering (C) Orientation (D) Setting

Last Answer : (C) Orientation

What generator characteristics must be considered when alternators are synchronized for parallel operation?

Description : What generator characteristics must be considered when alternators are synchronized for parallel operation?

Last Answer : Output voltage, frequency, and phase relationships.

Which of the following are the functions of operating system? i) recovering from errors ii) facilitating input/output iii) facilitating parallel operation iv) sharing hardware among users v) implementing user interface A) i, ii, ii, and v only B) i, ii, iii, and iv only C) ii, iii, iv and v only D) All i, ii, iii, iv and v

Description : Which of the following are the functions of operating system? i) recovering from errors ii) facilitating input/output iii) facilitating parallel operation iv) sharing hardware among users v) implementing user interface A) i, ii, ... only C) ii, iii, iv and v only D) All i, ii, iii, iv and v

Last Answer : D) All i, ii, iii, iv and v

Use the new system as the same time as the old system to compare the results. This is known as … A) Procedure Writing B) Simultaneous processing C) Parallel Operation D) File Conversion

Description : Use the new system as the same time as the old system to compare the results. This is known as … A) Procedure Writing B) Simultaneous processing C) Parallel Operation D) File Conversion

Last Answer : C) Parallel Operation

The ideal level of operation for a pure monopoly firm is the level where (a) TR and STC curve are parallel to each other ; (b) TR = TC ; (c) TR = Total variable cost; (d) TR is less than STC

Description : The ideal level of operation for a pure monopoly firm is the level where (a) TR and STC curve are parallel to each other ; (b) TR = TC ; (c) TR = Total variable cost; (d) TR is less than STC 

Last Answer : (a) TR and STC curve are parallel to each other ; 

State how 'parallel operation of transformers' helps in energy conservation.

Description : State how 'parallel operation of transformers' helps in energy conservation.

Last Answer : 'Parallel operation of transformers' helps in energy conservation: The transformers operate near their maximum efficiency at around 70 % to 100 % of their rated loads. For a huge load system drawing highly ... if of higher rating may be put in service while the first one may be switched off.

The condition for parallel operation of two inverters is

Description : The condition for parallel operation of two inverters is • Amplitude of voltages should be same. • Frequency of voltages should be same. • Both the voltages should be in same phase. • All the three above.

Last Answer : The condition for parallel operation of two inverters is • Amplitude of voltages should be same. • Frequency of voltages should be same. • Both the voltages should be in same phase. • All the three above.

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

Description : 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

For the parallel operation of two or more D.C. compound generators, we should ensure that?

Last Answer : For the parallel operation of two or more D.C. compound generators, we should ensure that series fields of all generators should be either on positive side or negative side of the armature.

For the parallel operation of single phase transformers it is necessary that they should have?

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.

parallel operation of mosfet can be done more easily as compared to thyristor. why?

Description : parallel operation of MOSFET can be done more easily as compared to thyristor. why?

Last Answer : Parallel operation of MOSFET can be done more easily as compared to thyristor because the resistance of MOSFET is increases with increase in temperature. MOSFET have the positive temperature coefficient. In ... the parallel operation of MOSFET can be done more easily as compared to the thyristor.

Explain the series and parallel operation of MOSFET. Which is suitable and why ?

Description : Explain the series and parallel operation of MOSFET. Which is suitable and why?

Last Answer : Series operation of MOSFET: To increase voltage handling capability MOSFETs are connected in series. When the MOSFETs are connected in series each MOSFET should turn on and turn off ... on and turn off time and transconductance. Each MOSFET should share current equally.