State what is the significance of conducting phasing out test on a 3-phase transformer? Explain its procedure with a suitable connection diagram.

State what is the significance of conducting phasing out test on a 3-phase transformer? Explain its procedure with a suitable connection diagram.
by

2 Answers

Answer :

Objective: - This test is carried out to identify primary & secondary windings belonging to same phase.

Figure: 

image

Procedure:-  Short primary & secondary winding of other phases expect the one under test. Connect voltmeter to secondary winding. A small DC current is circulated through the primary winding through switch. Now with the help of switch interrupt the DC supply instantly & repeatedly. If voltmeter indicator deflects than it indicates the two windings concerned belong to the same phase. If not deflect then two windings are not belong to same phase. Repeat the procedure by connecting voltmeter to secondary side to next secondary winding till voltmeter gives deflection. In this way we can search the phasing out test. 

by

Answer :

-Short primary & secondary winding of other phases expect the one under test. -Connect voltmeter to secondary winding. -A small DC current is circulated through the primary winding through switch. -Now with the help of switch interrupt the DC supply instantly & repeatedly. -If voltmeter indicator deflects than it indicates the two windings concerned belong to the same phase. -If not deflect then two windings are not belong to same phase. -Repeat the procedure by connecting voltmeter to secondary side to next secondary winding till voltmeter gives deflection. -In this way we can search the phasing out.


OR


-This test is carried to find out the corresponding HV and LV phase winding. -The circuit diagram is as shown in figure. Here normal ac voltage is applied to one of the HV or LV windings. In this case to HV winding and the voltages across all three LV windings are measured. -The winding across which is much more compared to other two windings represents the secondary of the winding to which supply is connected. -The test repeated for finding out remaining concerned secondary windings in the same manner.

by

Related questions

With the help of neat diagram, describe the procedure to carry out phasing out test on a 3 phase transformer. Also state the purpose of conducting this test on 3 phase transformer.

Description : With the help of neat diagram, describe the procedure to carry out phasing out test on a 3 phase transformer. Also state the purpose of conducting this test on 3 phase transformer.

Last Answer : i) This test is carried out on 3-ph transformer to identify primary & secondary winding belonging to the same phase. ii) As shown in fig above all primary & secondary phases ... of this test is to check the respective phases of primary & secondary windings in 3-ph transformer

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.

for Delta-Star connection of 3-phase transformer: i) Draw the connection diagram ii) List any two advantages of this connection iii) State its area of application.

Description : for Delta-Star connection of 3-phase transformer: i) Draw the connection diagram ii) List any two advantages of this connection iii) State its area of application. 

Last Answer : Disadvantages: i) In this type of connection, the secondary voltage is not in phase with the primary. Hence it is not possible to operate this connection in parallel with star-star or delta-delta ... iv) As line current is equal to phase current the conductor size of winding should be large. 

Explain the working of single phasing preventer with neat diagram.

Description : Explain the working of single phasing preventer with neat diagram.

Last Answer : Working of single phasing preventer:  Single phasing preventers are generally used for small / medium capacity motors. Single phasing preventers are connected in secondary of line CTs. These ... contact gets opened which stops the motor to avoid further damage when single phasing occurs. 

Explain single phasing preventer with neat sketch diagram.

Description : Explain single phasing preventer with neat sketch diagram.

Last Answer : Single phasing preventer: Single phasing preventers are generally used for small / medium capacity motors. Single phasing preventers are connected in secondaries of line CTs. These mainly contains ... command is given to circuit breaker or starter. Thus it protects motor from damage.

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:   

Explain MCB and ELCB with connection diagram supplying single phase load.

Description : Explain MCB and ELCB with connection diagram supplying single phase load. 

Last Answer : OR OR Explanation: * MCB provides short circuit protection. * MCB provides overload protection * ELCB provides earth fault protection. * MCB is in series with ... occurs, the ELCB cuts off the power within the time of 0.1 sec. automatically to protect the personnel. 

The single phasing relays are used for the protection of (a) single phase motors only (b) two phase motors only (c) two single phase motors running in parallel (d) three phase motors

Description : The single phasing relays are used for the protection of (a) single phase motors only (b) two phase motors only (c) two single phase motors running in parallel (d) three phase motors

Last Answer : (d) three phase motors

Give any two advantages of open delta connection of 3-phase transformer.

Last Answer : Advantages of open delta connection of 3-phase transformer:  1. When one of the phase in case of delta-delta bank is out of order by any reason, the service will be continued till ... demand in future (about 33%) will be supplied by converting open delta connection to delta-delta connection.

Which of the following 3-phase connection of a transformer causes interference with the

Description : Which of the following 3-phase connection of a transformer causes interference with the neighbouring communication lines:  (A) Delta-Star (B) Star-Delta (C) Delta-Delta (D) Star-Star

Last Answer : Which of the following 3-phase connection of a transformer causes interference with the neighbouring communication lines: Star-Star

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

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

The method suitable for heating of a conducting medium is

Description : The method suitable for heating of a conducting medium is   (a) Induction heating (b) Indirect arc heating (c) Eddy current heating (d) Resistance heating

Last Answer : Induction heating is used for heating of a conducting medium

Which one is not single phasing preventer?

Description : Which one is not single phasing preventer? A. Frequency Sensing B. voltage sensing C. mechanical type D. Current sensing

Last Answer : Frequency Sensing is not single phasing preventer.

Explain with the neat circuit diagram only the scott connection scheme for conversion of three phase supply to two phase supply. Name one application of the same.

Description : Explain with the neat circuit diagram only the scott connection scheme for conversion of three phase supply to two phase supply. Name one application of the same.

Last Answer : Three-phase to Two-phase Transformation (Scott Connection of Transformers): Working: i) Scott connection can be used for three-phase to two-phase conversion using two single-phase transformers ... a 3-phase system with a two-phase system with the flow of power in either direction. 

Explain the procedure for finding out the polarity and ratio test in a CT with circuit diagram.

Description : Explain the procedure for finding out the polarity and ratio test in a CT with circuit diagram. 

Last Answer : Polarity test: Connect the circuit as shown in figure with a battery, switch and AVOmeter. Now momentarily close the switch S and see the deflection in the AVOmeter. If it is in the direction as shown in the ... A2. Then see whether it confirms to reading of nameplate. Ratio = A1/A2. 

A CPA is conducting the first audit of a client’s financial statements. The CPA hopes to reduce the audit work by consulting with the predecessor auditor and reviewing the predecessor's working papers. This procedure is a. Acceptable if the CPA refers in the audit report to reliance upon the predecessor auditor's work. b. Required if the CPA is to render an unqualified opinion. c. Unacceptable because the CPA should bring an independent viewpoint to a new engagement. d. Acceptable if the client and the predecessor auditor agree to it.

Description : A CPA is conducting the first audit of a client's financial statements. The CPA hopes to reduce the audit work by consulting with the predecessor auditor and reviewing the predecessor's working papers. ... to a new engagement. d. Acceptable if the client and the predecessor auditor agree to it.

Last Answer : Acceptable if the client and the predecessor auditor agree to it.

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 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.

Which three-phase connection can be used in a transformer to introduce a phase difference of

Description : Which three-phase connection can be used in a transformer to introduce a phase difference of 30o between its output and corresponding input line voltages  (A) Star-Star (B) Star-Delta (C) Delta-Delta (D) Delta-Zigzag

Last Answer : Which three-phase connection can be used in a transformer to introduce a phase difference of 30o between its output and corresponding input line voltages  (A) Star-Star (B) Star-Delta (C) Delta-Delta (D) Delta-Zigzag

The transformer connection which has gained considerable popularity to serve 3-phase

Description : The transformer connection which has gained considerable popularity to serve 3-phase equipment and single phase lighting load is • Star/Star • Delta/Delta • Delta/Star • Star/Delta

Last Answer : The transformer connection which has gained considerable popularity to serve 3-phase equipment and single phase lighting load is Delta/Star

Explain working of pressure switch with suitable diagram. State the function of differential setting in pressure switch.

Description : Explain working of pressure switch with suitable diagram. State the function of differential setting in pressure switch.

Last Answer : Pressure switch is used to turn on/off when specified pressure is reached. It consists of a pressure port and bellows. When pressure is applied, bellows expand and actuate the snap action ... pressure setting i.e. hysteresis setting. This prevents chattering of pressure switch contacts.

In your opinion, why are auto makers phasing out the manual transmission on a lot of their vehicles?

Description : In your opinion, why are auto makers phasing out the manual transmission on a lot of their vehicles?

Last Answer : I know a few people will turn their nose up and huff, by saying automatic transmissions are now just as economical as a manual so why bother with a manual. BUT, that doesn’t really answer the question, are they scaling back or phasing out because people have lost the skill, or are to lazy?

In which country, the recent international agreement on phasing out Hydro Fluoro Carbons (HFCs) was signed? (A) Rwanda (B) Morocco (C) South Africa (D) Algeria

Description : In which country, the recent international agreement on phasing out Hydro Fluoro Carbons (HFCs) was signed? (A) Rwanda (B) Morocco (C) South Africa (D) Algeria 

Last Answer : (A) Rwanda

Draw schematic diagram of welding transformer showing constructional features of a welding transformer. Also explain its working.

Description : Draw schematic diagram of welding transformer showing constructional features of a welding transformer. Also explain its working.

Last Answer : Constructional features of welding transformer: Working of welding transformer: i) It is a step down transformer that reduces the voltage from the source voltage to a voltage desired according to the demands of ... 230 V, 415 V Secondary voltage - 40 to 60 V Secondary current - 200 to 600 A

What is meant by antenna gain? A. The final amplifier gain minus the transmission line losses (including any phasing lines present) B. The ratio of the amount of power produced by the antenna compared to the output power of the transmitter C. The ratio of the signal in the backward direction D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

Description : What is meant by antenna gain? A. The final amplifier gain minus the transmission line losses (including any phasing lines present) B. The ratio of the amount of power produced by the antenna ... D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

Last Answer : D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

What are the effects of single phasing?

Description : What are the effects of single phasing?  

Last Answer : a. Current will increase √3 times. b. More heat in stator and rotor parts. c. Insulation failure and short circuit & Ground fault may occur. 

Does over load relay give 100% guarantee against the single phasing?

Description : Does over load relay give 100% guarantee against the single phasing?  

Last Answer : No. It depends on the motor load and the motor winding (star or delta).  

What is the current in single phasing?

Description : What is the current in single phasing?

Last Answer : 2 times of rated current.

What is meant by ‘Single Phasing’?*

Description : What is meant by ‘Single Phasing’?*

Last Answer : When one supply is open circuit in a three phase motor.

What is single phasing?

Description : What is single phasing?

Last Answer : Single phasing is a condition in three phase motors and transformers wherein the supply to one of the phases is cut off.

The single phasing relays are used for the protection of?

Last Answer : The single phasing relays are used for the protection of three phase motors.

With the help of neat diagram, explain the construction of current transformer.

Description : With the help of neat diagram, explain the construction of current transformer. 

Last Answer : Construction of current transformer:   C.T. has bar type conductor, which behaves as primary winding. The primary of C.T. carries large current Ip which is to be measured, so the bar ... sectional area is small. An ammeter of small range is connected across the secondary as shown in figure. 

With the help of suitable diagram, explain how humidity is measured with dry and wet bulb thermometer.

Description : With the help of suitable diagram, explain how humidity is measured with dry and wet bulb thermometer.

Last Answer : Explanation:- 1. A psychrometer, or wet-and-dry-bulb thermometer, consists of two thermometers, one that is dry and one that is kept moist with distilled water on a sock or ... , and in the HVAC industry for proper refrigerant charging of residential and commercial air conditioning systems. 

Describe procedure for calibration of ammeter with diagram.

Description : Describe procedure for calibration of ammeter with diagram.

Last Answer : Procedure for Calibration of Ammeter:  In this method, DC potentiometer is used for measurement of voltage across a standard low resistance.  Connect the circuit as shown in the figure, ... S = resistance of potentiometer  And the currents are compared for finding out error in ammeter.

Deliverables of test design phase include all the following except A. Test data B. Test data plan C. Test summary report D. Test procedure plan

Description : Deliverables of test design phase include all the following except A. Test data B. Test data plan C. Test summary report D. Test procedure plan

Last Answer : C. Test summary report

What is energy flow diagram? State its significance from Energy Audit point of view.

Description : What is energy flow diagram? State its significance from Energy Audit point of view.

Last Answer : Example energy flow diagram: Significance of energy flow diagram: 1. Energy flow diagram, also known as Sankey diagram, is a specific type of flow diagram in which the width of the arrow is ... from left of the diagram. The outputs (useful and leakages/losses of energy) are shown in diagram.

In Scott connection transformer the turns ratio of main winding and teaser winding is ?

Last Answer : Turns ratio= N1/ N2 IN Scott connection Main transformer turns ratio = N1 /N2 Teaser transformer turns ratio= 0.866N1/N2 Where N1= number of turns in primary winding N2= number of turns in secondary winding

Explain the single pass transformer design procedure step by step by giving its flowchart.

Description : Explain the single pass transformer design procedure step by step by giving its flowchart.

Last Answer : single pass transformer design procedure step by step by giving its flowchart:

Draw the circuit diagram for finding out the knee point voltage and explain the procedure.

Description : Draw the circuit diagram for finding out the knee point voltage and explain the procedure.

Last Answer : Connect the circuit as shown. O/P of variac should be zero. Increase it to 5 Volts and take down the value of current from the ammeter. Now increase the voltage by 10% (5 + 10% = ... point. Above this they cannot detect the fault correctly. Measuring CT operate in the ankle region.   

The removal of paint from electrical equipment, such as generators, should be cautiously undertaken because ____________. A. the mechanical shock of paint removal lessens the dielectric strength of the insulation B. the paint dust is composed of abrasive and semi-conducting materials which impair insulation C. paint dust buildup has a tendency to cause corrosion D. phase windings frequently become isolated from each other due to dust interference at the terminals

Description : The removal of paint from electrical equipment, such as generators, should be cautiously undertaken because ____________. A. the mechanical shock of paint removal lessens the dielectric strength ... phase windings frequently become isolated from each other due to dust interference at the terminals

Last Answer : Answer: B

In a single-phase full converter, the number of SCRs conducting during overlap is

Description : In a single-phase full converter, the number of SCRs conducting during overlap is   (a) 1 (b) 2 (c) 3 (d) 4 

Last Answer : 4

The most suitable material for transformer core is

Description : The most suitable material for transformer core is  (1) hot rolled grain oriented steel (2) cold rolled grain oriented steel (3) aluminium (4) copper

Last Answer : cold rolled grain oriented steel

Which type of flow is measured by hot wire anemometer and describe its working principle with suitable diagram.

Description : Which type of flow is measured by hot wire anemometer and describe its working principle with suitable diagram. 

Last Answer : Heat transfer flowmeters this type of flowmeter measures the rise in temperature of the fluid after a known amount of heat has been added to it. Its theory is based upon the specific heat equation ... a supply so as to maintain the wire temperature constant, when the amount of heat transfer varies

What is pressure calibration? State stepwise procedure to test the accuracy of pressure gauge with dead weight tester.

Description : What is pressure calibration? State stepwise procedure to test the accuracy of pressure gauge with dead weight tester.

Last Answer : Explanation- The handle is fully drawn out and the oil is allowed to enter in the cylinder (i.e. gauge and piston). A known accurate weight is placed on the platform. The area of ... reduce the friction between the piston and cylinder, the piston is gradually rotated while a reading being taken

What Is Buchholz Relay And The Significance Of It In To The transformer ?

Description : What Is Buchholz Relay And The Significance Of It In To The transformer ?

Last Answer : Buchholz Relay is a device which is used for the protection of transformer from its internal faults, it is a gas based relay. whenever any internal fault occurs in a transformer, the Buchholz Relay ... then it stop its sound itself other wise it trips the circuit by its own tripping mechanism.

What is buchholz relay and the significance of it in to the transformer?

Description : What is buchholz relay and the significance of it in to the transformer?

Last Answer : A:Buchholz relay is a gas based relay which is used for the protection of transformer from its internal faults. whenever any internal fault occurs in a transformer, the buchholz relay at once gives an ... then it stop its sound itself other wise it trips the circuit by its own tripping mechanism.

what is Buchholz relay and the significance of it in to the transformer?

Description : what is Buchholz relay and the significance of it in to the transformer?

Last Answer : Buchholz relay is a device which is used for the protection of transformer from its internal faults, it is a gas based relay. whenever any internal fault occurs in a transformer, the Buchholz ... circuit then it stop its sound itself otherwise it trips the circuit by its own tripping mechanism.

Discuss the significance of having clause with group by statement with suitable example. -Technology

Description : Discuss the significance of having clause with group by statement with suitable example. -Technology

Last Answer : Sometimes we do not want to see the whole output produced by a statement with Group By clause. We want to see the output only for those groups which satisfy some condition. It means we want ... the total amount of all type of transactions, it will only display the total of credit transactions only.

Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter.

Description : Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter. 

Last Answer : Circuit diagram for measurement of single phase power using dynamometer type wattmeter: Explanation: It consists of two stationary coils, called current coils and one moving coil, called voltage or ... i.e. power. The meter can be calibrated directly to indicate the power in watts. 

Explain the working of resistance split phase induction motor with a neat diagram.

Description : Explain the working of resistance split phase induction motor with a neat diagram.

Last Answer : Circuit diagram of resistance split single phase induction motor:   * Working of resistors split single phase induction motor: To make a single phase induction motor self-starting, we ... function is to automatically disconnected the starting winding from the supply Once motor is started.