Give any two advantages of star-star connection in 3-ф transformers.

by

1 Answer

Answer :

Advantages of star-star connection in 3-ф transformers: 1. It is possible to use the transformer for 3-phase, four wire system because of neutral. 2. The phase shift between primary and secondary emfs is zero. 3. As phase current equal line current, windings have to carry large currents; hence can be used for supplying large load currents. 4. As phase voltage is 1/root 3 times line voltage, the no.of turns required for primary and secondary are less, hence economical.

by

Related questions

If Ф = angle(G(jw)H(jw)) where w is the gain crossover frequency of Bode plot of the system, phase margin is ...

Description : If Ф = angle(G(jw)H(jw)) where w is the gain crossover frequency of Bode plot of the system, phase margin is  A) -180+ Ф B) 180- Ф C) 180+ Ф D) -180- Ф

Last Answer : Ans:Option C

Which of the following connection of transformers will give highest value of secondary voltage ?

Description : Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary

Last Answer : Which of the following connection of transformers will give highest value of secondary voltage ? (A) Delta primary delta secondary (B) Delta primary star secondary (C) Star primary star secondary (D) Star primary delta secondary

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. 

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.

Why Delta Star Transformers are used for Lighting Loads?

Description : Why Delta Star Transformers are used for Lighting Loads?

Last Answer : A. For lighting loads, neutral conductor is must and hence the secondary must be star winding.This lighting load is always unbalanced in all three phases. To minimize the current unbalance in the primary we use delta winding in the primary. So delta / star transformer is used for lighting loads.

Why Delta Star Transformers are used for Lighting Loads?

Description : Why Delta Star Transformers are used for Lighting Loads?

Last Answer : For lighting loads, neutral conductor is must and hence the secondary must be star winding and this lighting load is always unbalanced in all three phases.  To minimize the current unbalance in the primary we use delta winding in the primary So delta / star transformer is used for lighting loads.

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 

Star/star transformers work satisfactorily when?

Last Answer : Star/star transformers work satisfactorily when load is balanced .

The line voltage EL in a star connection is equal to.... (Ep = phase voltage)

Description : The line voltage EL in a star connection is equal to.... (Ep = phase voltage)

Last Answer : The line voltage EL in a star connection is equal to √3 .Ep (Ep = phase voltage)

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 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.

What term is used to describe two or more computers that are linkedto eachother? A) Star connection B) Computer system C) Computer network D) Net

Description : What term is used to describe two or more computers that are linkedto eachother? A) Star connection B) Computer system C) Computer network D) Net

Last Answer : Computer network

How to share data connection with other devices on Samsung Galaxy Star Pro S7260 -Biology

Description : How to share data connection with other devices on Samsung Galaxy Star Pro S7260 -Biology

Last Answer : answer:

What is Star Connection ?

Description : What is Star Connection ?

Last Answer : When three ends of three resistors are connected to a point and the other three ends are taken out to connect three lines or leads, it is called a star connection.

What advantage has the star connection over the delta connection ?

Description : What advantage has the star connection over the delta connection ?

Last Answer : A. Each star connection transformer is wound for only 57.7% of line voltage . In hv transmission, this admits of much smaller transformer being built for high voltage than possible with delta connection, because of less insulation.

State the voltage and current relation in star and delta connection.

Description : State the voltage and current relation in star and delta connection. 

Last Answer : In star connection line current is equal to the phase current and line voltage is √3 times that of phase voltage. In delta connection line voltage is equal to the phase voltage and line current is √3 times that of phase current. 

What are the value of voltage and current in star connection and in delta connection?

Description : What are the value of voltage and current in star connection and in delta connection?

Last Answer : Star connection a. IL = IPh. b. VL = √3 VPh. ∴ VPh = VL/√3. Note: in star connection we are getting neutral point and we can able to measure the phase as well as line voltage. Delta connection a. VL = VPh. b. IL = √3 IPh. ∴ IPh = IL/√3.

Which topology requires a multipoint connection? A) Mesh B) Star C) Bus D) Ring

Description : Which topology requires a multipoint connection? A) Mesh B) Star C) Bus D) Ring

Last Answer : Bus

Draw the star and delta connection. State any one conversion formula.

Description : Draw the star and delta connection. State any one conversion formula.

Last Answer : star and delta connection

Compare star and Delta Connection.

Description : Compare star and Delta Connection.

Last Answer : Compare Star and Delta connected system:  Star connected system Delta connected system   In STAR connection, the starting or finishing ends (Similar ends) of three coils are connected together to form the ... VPH Line Current is √3 times of Phase Current. i.e. IL = √3 IPH

Write the relation between phase and line current, phase and line voltage for Star connection.

Description : Write the relation between phase and line current, phase and line voltage for Star connection.

Last Answer : Line voltage is equal to root three times of phase voltage and line and phase currents are equal in star connection

What is difference between Star and Delta Connection?

Description : What is difference between Star and Delta Connection?

Last Answer : Star is        1. Open ckt       2. At center point present  neutral   Delta is     1.   Closed ckt 2.      Neutral not present in this case 

Two transformers A and B having equal outputs and voltage ratios but unequal percentage

Description : Two transformers A and B having equal outputs and voltage ratios but unequal percentage impedances of 4 and 2 are operating in parallel. The transformer A will be overloaded by 

Last Answer : Two transformers A and B having equal outputs and voltage ratios but unequal percentage impedances of 4 and 2 are operating in parallel. The transformer A will be overloaded by 33%

Two 3-phase transformers cannot be operated in parallel, if their :

Description : Two 3-phase transformers cannot be operated in parallel, if their :  (A) kVAs are different (B) phase sequences are different (C) % impedances are different (D) voltage ratios are different

Last Answer : Two 3-phase transformers cannot be operated in parallel, if their : phase sequences are different

Two transformers having the same p.u. impedance connected in parallel share the connected load

Description : Two transformers having the same p.u. impedance connected in parallel share the connected load (A) equally (B) in proportion to the respective ratings (C) in proportion to the voltage ratio (D) in proportion to the zero phase displacement

Last Answer : Two transformers having the same p.u. impedance connected in parallel share the connected load in proportion to the respective ratings

Classification of transformers

Description : Classification of transformers

Last Answer : Classification of transformers: Transformers are classified on the basis of core construction, frequency, and power. These are the three broad groups of transformers. a) Core construction ... Power transformers are used in conjunction with generators, 2. Distribution transformer

Distribution transformers have good all day efficiency due to

Description : Distribution transformers have good all day efficiency due to  (A) low copper loss (B) low iron loss (C) low copper and iron loss (D) None of these

Last Answer : Distribution transformers have good all day efficiency due to low iron loss

Core type transformers are popular in___________.

Description : Core type transformers are popular in___________.  (A) High voltage applications (B) Low voltage applications (C) All of the above (D) None of the above

Last Answer : Core type transformers are popular in High voltage applications

The friction losses in Real Transformers are :

Description : The friction losses in Real Transformers are :  (A) 0% (B) 5% (C) 25% (D) 50%

Last Answer : A

Which of the following is the advantage of using CRGO steel in transformers?

Description : Which of the following is the advantage of using CRGO steel in transformers? A) High magnetic flux density B) Low permeability C) Both A and B D) None of these

Last Answer : It definitely High Magnetic Flux Density since a crgo steel has always a more around 3% of silicon proportion among the remaining ferrite which make cold rolled grain oriented steel having high flux magnetic ... for more about the crgo core you can learn here https://nicoreindia.com/crgo-core/

Non -loading heat run test on transformers is performed by means of

Description : Non -loading heat run test on transformers is performed by means of

Last Answer : Non -loading heat run test on transformers is performed by means of Sumpner's test

Consider the following statements regarding three-phase transformers in Open -Delta (V -V) connections

Description : Consider the following statements regarding three-phase transformers in Open -Delta (V -V) connections :  1. Being a temporary remedy when one transformer forms of Delta -Delta system is &imaged, and removed from service.  ... and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

Last Answer : Consider the following statements regarding three-phase transformers in Open -Delta (V -V) connections :  1. Being a temporary remedy when one transformer forms of Delta -Delta system is &imaged, and removed from service.  ... and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

In potential transformers, the secondary turns are increased slightly and the primary and secondary windings...

Description : In potential transformers, the secondary turns are increased slightly and the primary and secondary windings are wound as closely as possible to compensate for  (a) Phase angle and ratio error, ... loss and hysteresis loss, respectively  (d) The hysteresis loss and eddy current loss, respectively

Last Answer : In potential transformers, the secondary turns are increased slightly and the primary and secondary windings are wound as closely as possible to compensate for Ratio and phase angle error, respectively 

Regulating transformers are used in power systems for control of :

Description : Regulating transformers are used in power systems for control of : a) voltage b) power factor c) power flow d) all of the above

Last Answer : Regulating transformers are used in power systems for control of :  power flow 

Distribution transformers have core losses:

Description : Distribution transformers have core losses:  (1) More than full load copper losses (2) Equal to full load copper losses (3) Less than full load copper losses (4) W Negligible compared to full load copper losses

Last Answer : Distribution transformers have core losses:  Less than full load copper losses.

of what use are current and voltage transformers in protective systems

Last Answer : Current transformers (CT) : Current transformer (CT) actually step down the high current to low current for the operation of relays. Current transformer is use for measurement of ... use for relay. This is about potential transformer.

which type of oil is use in transformers ?

Description : which type of oil is use in transformers ?

Last Answer : Mineral oil is use in transformers .

Epoxy resin transformers are more suitable in hazardous areas. Give reason.

Description : Epoxy resin transformers are more suitable in hazardous areas. Give reason.

Last Answer : Reason for Epoxy resin transformers are more suitable in hazardous areas :   1. Core used is of CRGO M4-M3 circular size, minimizes leakage reactance and hence core losses will be less. 2. Winding ... of oil there is no need of testing the dielectric strength of oil or no filtration of oil.

Mention any two main advantages of star topology over bus topology. -Technology

Description : Mention any two main advantages of star topology over bus topology. -Technology

Last Answer : (i)It has centralized control.(ii) Fault diagnosis is easy.

What are the advantages the star health insurance plan?

Description : What are the advantages the star health insurance plan?

Last Answer : Star's rates are pretty much equal to other plans out there. However, it's not an HMO which is a huge plus. You can keep your current doctors and specialists instead of having to search through a list of approved providers.

What are the advantages of star-delta starter with induction motor?

Description : What are the advantages of star-delta starter with induction motor?

Last Answer : The main advantage of using the star delta starter is reduction of current during the starting of the motor. Starting current is reduced to 3-4 times of current of Direct online starting Hence the starting current is reduced , the voltage drops during the starting of motor in systems are reduced

What is network topology? Explain star and bus topology with its advantages

Description : What is network topology? Explain star and bus topology with its advantages 

Last Answer : Topology of LANs  Networks can be laid out in different ways. The physical layout, or shape of network, or the way in which network connections are made is called a topology. It refers ... computer failure does not bring down the whole network It is more flexible among the remaining topology.

What are the advantages of the use of frequency converter instead of star-delta or soft starter?

Description : Can you guys explain the advantages of frequency converter against the star delta or soft starter?

Last Answer : ¬Soft starters  A soft starter is, as you would expect, a device which ensures a soft starting of a motor. A softstarter has different characteristics to the other starting ... at rated current from zero to full speed. Frequency converters are becoming cheaper all the time.

Two transformers of identical voltages but different capacities are operated in parallel, for satisfactory load sharing: a) Impedances should be equal b) Per unit impedance must be equal c) per unit impedance and X/R ratio must be equal d) Impedance and X/R ratio must be equal

Description : Two transformers of identical voltages but different capacities are operated in parallel, for satisfactory load sharing: a) Impedances should be equal b) Per unit impedance must be equal c) per unit impedance and X/R ratio must be equal d) Impedance and X/R ratio must be equal

Last Answer : Ans: C

Equalization of the power factors of two alternators operating in parallel is accomplished _____________. A. manually, by adjusting the governor controls B. automatically, by automatic voltage regulators C. manually, adjusting the output of current transformers D. automatically, by the designed action of the governors

Description : Equalization of the power factors of two alternators operating in parallel is accomplished _____________. A. manually, by adjusting the governor controls B. automatically, by automatic voltage regulators ... the output of current transformers D. automatically, by the designed action of the governors

Last Answer : Answer: B

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

Is it Possible to Change Three Phase to Two Phase or Vice-Versa with Standard Transformers?

Description : Is it Possible to Change Three Phase to Two Phase or Vice-Versa with Standard Transformers?

Last Answer : Yes. This is a very practical application for standard single phase off-the-shelf transformers. Some typical voltage combinations are as follows: 480 volts three phase to 240 volts two phase, or 240 volts ... 240 volts three phase to 240 volts two phase. Please refer to us for an exact schematic.

Circuit breakers are essentially (a) current carrying contacts called electrodes (b) arc extinguishers (c) circuits to break the system (d) transformers to isolate the two systems (e) any of the above

Description : Circuit breakers are essentially (a) current carrying contacts called electrodes (b) arc extinguishers (c) circuits to break the system (d) transformers to isolate the two systems (e) any of the above

Last Answer : (a) current carrying contacts called electrodes

[75] Two transformers are connected in parallel. These transformers do not have equal percentage impedance which results A. Short-circuiting of the secondaries B. Power factor of one of the transformers is leading while that of the other lagging C. Transformers having higher copper losses will have negligible core losses D. Loading of the transformers not in proportion to their kVA ratings.

Description : [75] Two transformers are connected in parallel. These transformers do not have equal percentage impedance which results A. Short-circuiting of the secondaries B. Power factor of one of the ... have negligible core losses D. Loading of the transformers not in proportion to their kVA ratings.

Last Answer : D. Loading of the transformers not in proportion to their kVA ratings