Why we use Vacuum Circuit Breaker in High Transmission System and not Air Circuit Breaker?

Why we use Vacuum Circuit Breaker  in  High Transmission System and not Air Circuit Breaker?
by

1 Answer

Answer :

A:Vacuum has high arc quenching property compare to air . The dielectric strength of vacuum is equal to 8 times than air . Hence  vacuum circuit breaker is used in High voltage line and air circuit breaker is used in low voltage lines.
by

Related questions

What is the difference between Isolator and Circuit Breaker?

Description : What is the difference between Isolator and Circuit Breaker?

Last Answer : A: Isolator is a off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits. it is manually operated ... specification 1) rated current 2) short circuit breaking capacity and 3) Instantaneous tripping current.

Explain the working principle of the circuit breaker

Description : Explain the working principle of the circuit breaker

Last Answer : A:Circuit Breaker is one which makes or breaks the circuit.It has two contacts namely fixed contact & moving contact. Under normal condition the moving contact comes in contact with fixed contact thereby forming ... . Arc is extinguished by the Arc Quenching media like air, oil, vacuum, SF6 gas etc.

What is difference between fuse and breaker?

Description : What is difference between fuse and breaker?

Last Answer : A: (i) Fuse performs both detection and interruption functions. Circuit breaker performs interruption function only. The detection of fault is made by relay system. (ii) The breaking capacity of ... , replacement is required in the fuse. In case of circuit breaker, replacement is not required.

Why we use ac system in India why not dc ?

Description : Why we use ac system in India why not dc ?

Last Answer : A:Firstly, the output of power stations comes from a rotary turbine, which by it's nature is AC and therefore requires no power electronics to convert to DC. Secondly it is much easier to ... the sine wave current will naturally tend to zero at some point making the current easier to interrupt.

what is ACSR cable and where we use it?

Description : what is ACSR cable and where we use it?

Last Answer : A: ACSR means Aluminium conductor steel reinforced, this conductor is used in transmission & distribution.

How can we reduce the effect of corona?

Description : How can we reduce the effect of corona?

Last Answer : 1. By increasing conductor size: By increasing conductor size, the voltage at which corona occurs is raised and hence corona effects are considerably reduced. 2. By increasing conductor spacing: ... , the voltage at which corona occurs is raised and hence corona effects can be eliminated.

When we connect the large capacitor bank in series ?

Description : When we connect the large capacitor bank in series ?

Last Answer : A :we connect large capacitor bank in series to improve the voltage power supply at the load end in balanced transmission line when there is considerable voltage drop along the balanced transmission line due ... - %6 )of the rated high terminal voltage )the large capacitor bank is used in series.

what is power factor? whether it should be high or low? why?

Description : what is power factor? whether it should be high or low? why?

Last Answer : A:Power factor is the ratio of true power to apparent power. It has to be ideally 1. If it is too low then cable over heating & equipment overloading will occur. if it is greater than 1 then load will ... : 0.95 to meet actual power, load has to draw less current(V constant),result in less losses).

What are the various types of tariff?

Description : What are the various types of tariff?

Last Answer : 1. Simple tariff 2. Flat rate tariff 3. Block rate tariff 4. Two-part tariff 5. Maximum demand tariff 6. Power factor tariff 7. Three-part tariff

What is tariff?

Description : What is tariff?

Last Answer : The rate at which electrical energy is supplied to a consumer is known as tariff. The tariff should include the following items: (i) Recovery of cost of producing electrical energy at the power ... of cost of operation and maintenance of supply (iv) A suitable profit on the capital investment.

What is corona?

Description : What is corona?

Last Answer : The phenomenon of violet glow, hissing noise and production of ozone gas in an overhead transmission line is known as corona.

What is meant by Sag?

Description : What is meant by Sag?

Last Answer : The difference in level between points of supports and the lowest point on the conductor is called sag.

Which type of motor is used in trains, what is the rating of supply used?

Description : Which type of motor is used in trains, what is the rating of supply used?

Last Answer : A:Dc series is in the trains to get high starting torque while starting of the trains and operating voltage is 1500v dc.

Why electricity in India is in the multiples of 11 like 11kv, 22kv, 33kv ?

Description : Why electricity in India is in the multiples of 11 like 11kv, 22kv, 33kv ?

Last Answer : A:Transformer Induced voltage equation contains 4.44 factor. E -Induced emf per phase T -number of turns f -frequency Φ -maximum flux per pole From the equation we see that E is proportional to 4.4 and it is in turn multiple of 11.So always transmission voltage is multiple of 11

What is reverse power relay?

Description : What is reverse power relay?

Last Answer : A:Reverse Power flow relay are used in generating stations's protection. A generating stations is supposed to fed power to the grid and in case generating units are off,there is no generation in the ... power from grid. To stop the flow of power from grid to generator we use reverse power relay.

What is the difference between over voltage relay and over current relay?

Description : What is the difference between over voltage relay and over current relay?

Last Answer : A:The current increases not only for over voltages but also for under voltage(As most of the loads are non-linear in nature). So,the over voltage protection & over current protection are completely ... , for a better protection of the system.It should have both over voltage & over current relay.

What is derating?

Description : What is derating?

Last Answer : A:The current currying of cables will change depending upon the site temperature (location of site), type of run (it will run through duct, trench, buried etc.), number of tray, depth ... of cable reduce than current currying capacity (which given to cable Catalogue) this is called derating.

Define IDMT relay?

Description : Define IDMT relay?

Last Answer : It is an Inverse Definite Minimum Time relay. In IDMT relay its operating is inversely proportional and also a characteristic of minimum time after which this relay operates. It is inverse in the sense; the tripping time will decrease as the magnitude of fault current increase.

Where should the lighting arrestor be placed in distribution lines?

Description : Where should the lighting arrestor be placed in distribution lines?

Last Answer : A:Near distribution transformers and out going feeders of 11kv and incomming feeder of 33kv and near power transformers in sub-stations.

What is the difference between MCB & MCCB, Where it can be used?

Description : What is the difference between MCB & MCCB, Where it can be used?

Last Answer : A: MCB is miniature circuit breaker which is thermal operated for overload condition and magnetically operated for short circuit protection. It is available in small current rating. MCCB is moulded case ... frequency may be inbuilt. Normally it is used where normal current is more than 100 A.

Explain types of Earthing.

Description : Explain types of Earthing.

Last Answer : A:The two types of earthing are Equipment earthing and system earthing. In Equipment earthing: body ( non conducting part) of the equipment should be earthed to safegaurd the human beings ... . This type of earthing is further classified into directly earthed, Impedance earthing, resistive earthing.

What is Ferranti effect?

Description : What is Ferranti effect?

Last Answer : A: When receiving end voltage is greater than the sending end voltage.

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 the difference between surge arrestor and lightning arrestor?

Description : What is the difference between surge arrestor and lightning arrestor?

Last Answer : A:Lightning Arrestor is installed outside and the effect of lightning is grounded where as surge arrestor installed inside panels comprising of resistors which consumes the energy and nullify the effect of surge.

Why syn. generators are used for the production of electricity?

Description : Why syn. generators are used for the production of electricity?

Last Answer : A:synchronous machines have capability to work on different power factor. Hence syn. generators are used for the production of electricity.

What will happen when power factor is leading in distribution of power?

Description : What will happen when power factor is leading in distribution of power?

Last Answer : A:If their is high power factor, i.e if the power factor is close to one: 1.losses in form of heat will be reduced, 2.cable becomes less bulky and easy to carry, and very cheap to afford, & 3. it also reduces over heating of transformers.

Describe the operation carried out in Thermal power stations?

Description : Describe the operation carried out in Thermal power stations?

Last Answer : A:The water is boiled in the boiler with the help of coal. This generates steam. This steam is allowed to hit the turbine hence the turbine rotates. The turbine is coupled with generator. So the mechanical energy of turbine is converted to electrical energy by Generator.

What is "pu" in electrical engineering?

Description : What is "pu" in electrical engineering?

Last Answer : PU stands for per unit and this will be used in power system single line diagram there it is like a huge electrical circuit with no of components (generators, transformers, loads) with different ratings (in ... into this basis. Those values are called as pu values. (p.u=actual value/base value).

What is Electric traction?

Description : What is Electric traction?

Last Answer : A:Electric traction means using the electric power for traction system to drive the locomotives.

What is meant by synchronous condenser?

Description : What is meant by synchronous condenser?

Last Answer : An over excited synchronous motor running on no load is known as synchronous condenser. It is used to improve the power factor of the system.

For interrupting capacitive currents which Circuit Breaker (CB) is used a) SF6 CB b) Oil CB c) Vacuum CB d) Air blast CB

Description : For interrupting capacitive currents which Circuit Breaker (CB) is used a) SF6 CB b) Oil CB c) Vacuum CB d) Air blast CB

Last Answer : Ans: Vacuum CB

What is vacuum circuit breaker? Define with cause and where be use it Device?

Description : What is vacuum circuit breaker? Define with cause and where be use it Device?

Last Answer : A breaker is normally used to break a circuit. While breaking the circuit, the contact terminals will be separated. At the time of separation an air gap is formed in between the terminals. Due to ... CB is having vacuum pressure the arc formation is interrupted. VCB's can be used up to 11kv.

Which of the following circuit breakers has high reliability and minimum maintenance ? (a) Air blast circuit breakers (b) Circuit breaker with SF6 gas (c) Vacuum circuit breakers (d) Oil circuit breakers

Description : Which of the following circuit breakers has high reliability and minimum maintenance ? (a) Air blast circuit breakers (b) Circuit breaker with SF6 gas (c) Vacuum circuit breakers (d) Oil circuit breakers

Last Answer : (b) Circuit breaker with SF6 gas

What is the use of vacuum breaker?

Description : What is the use of vacuum breaker? 

Last Answer : In case of loss of seal oil to generator seals vacuum breaker is used to bring TG to rest very quickly.

Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air? A. Open the machine on both ends so as to allow the air and dust to escape. B. Be certain that the circuit breaker is opened and tagged on the feeder panel. C. Be certain that the air is clean and as dry as possible. D. All of the above.

Description : Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air? A. Open the machine on both ends so as to allow the air and dust to escape. B. Be certain that the ... panel. C. Be certain that the air is clean and as dry as possible. D. All of the above.

Last Answer : Answer: D

What are the advantages of air blast circuit breaker over oil circuit breaker?

Description : What are the advantages of air blast circuit breaker over oil circuit breaker?

Last Answer : o The risk of fire is diminished o The arcing time is very small due to rapid buildup of dielectric strength between contacts o The arcing products are completely removed by the blast whereas oil deteriorates with successive operations

What are the types of air blast circuit breaker?

Description : What are the types of air blast circuit breaker?

Last Answer : Arial-blast type Cross blast Radial-blast

An AC generator operating in parallel loses its excitation without tripping the circuit breaker. This will __________. A. not affect the faulty generator due to the compensation of the other generators B. cause the slip rings to melt C. cause a low voltage differential to develop between the armature and the bus D. cause high currents to be induced in the field windings

Description : An AC generator operating in parallel loses its excitation without tripping the circuit breaker. This will __________. A. not affect the faulty generator due to the compensation of the other generators B. ... between the armature and the bus D. cause high currents to be induced in the field windings

Last Answer : Answer: D

Voltage failure of an AC generator may be caused by ____________. A. failure of the exciter generator B. a tripped bus circuit breaker C. high mica segments on the stator bus bar D. excessive prime mover speed

Description : Voltage failure of an AC generator may be caused by ____________. A. failure of the exciter generator B. a tripped bus circuit breaker C. high mica segments on the stator bus bar D. excessive prime mover speed

Last Answer : Answer: A

A device which can be used to check the calibration of a circuit breaker is a _________________. A. 500 volt megohmmeter B. portable low voltage high current testing unit C. standard digital multimeter D. clamp-on voltmeter

Description : A device which can be used to check the calibration of a circuit breaker is a _________________. A. 500 volt megohmmeter B. portable low voltage high current testing unit C. standard digital multimeter D. clamp-on voltmeter

Last Answer : Answer: B

Coast Guard Regulations (46 CFR) require each switchboard to have ___________. A. non-conductive deck covering at the frount B. non-conductive deck coverings at the rear C. a name plate for each circuit breaker D. all the above

Description : Coast Guard Regulations (46 CFR) require each switchboard to have ___________. A. non-conductive deck covering at the frount B. non-conductive deck coverings at the rear C. a name plate for each circuit breaker D. all the above

Last Answer : Answer: D

Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out? A. De-energize the applicable switchboard bus. B. Bypass the interlocks. C. Secure and tag the supply circuit breaker in the open position. D. Station a man at the circuit supply switch.

Description : Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out? A. De-energize the applicable switchboard bus. B. Bypass the interlocks. C. ... supply circuit breaker in the open position. D. Station a man at the circuit supply switch.

Last Answer : Answer: C

Which of the synchroscope illustrations depicts the appropriate direction of rotation and position for closing the circuit breaker when paralleling AC generators? EL-0053 A. A B. B C. C D. D

Description : Which of the synchroscope illustrations depicts the appropriate direction of rotation and position for closing the circuit breaker when paralleling AC generators? EL-0053 A. A B. B C. C D. D

Last Answer : Answer: D

The schematic diagram shown in the illustration uses symbol 'A' to represent a/an _________. EL-0011 A. non-renewable fuse link B. circuit breaker coil C. overload relay coil D. thermal overload heater

Description : The schematic diagram shown in the illustration uses symbol 'A' to represent a/an _________. EL-0011 A. non-renewable fuse link B. circuit breaker coil C. overload relay coil D. thermal overload heater

Last Answer : Answer: D

Which of the following problems will occur if the circuit breaker of the incoming alternator is closed and it is 180° out of phase with the loaded alternator when paralleling? A. The rotor of the loaded alternator will hunt. B. Severe cross currents will occur which could cause damage. C. The rotor of the incoming alternator will stop. D. Both alternators will parallel 180° out of phase.

Description : Which of the following problems will occur if the circuit breaker of the incoming alternator is closed and it is 180° out of phase with the loaded alternator when paralleling? A. The rotor of the ... The rotor of the incoming alternator will stop. D. Both alternators will parallel 180° out of phase.

Last Answer : Answer: B

Which of the following actions must be carried out prior to closing the alternator circuit breaker according to the graph shown in the illustration? EL-0002 A. Increase the alternator voltage. B. Decrease the line voltage. C. Increase the line voltage. D. Decrease the line frequency.

Description : Which of the following actions must be carried out prior to closing the alternator circuit breaker according to the graph shown in the illustration? EL-0002 A. Increase the alternator voltage. B. Decrease the line voltage. C. Increase the line voltage. D. Decrease the line frequency.

Last Answer : Answer: A

An alternator will fail to produce line voltage as a result of _____________. A. a closed circuit breaker B. oxidized slip rings C. improperly staggered brushes D. exciter generator failure

Description : An alternator will fail to produce line voltage as a result of _____________. A. a closed circuit breaker B. oxidized slip rings C. improperly staggered brushes D. exciter generator failure

Last Answer : Answer: D

In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This is accomplished by opening the _____________. A. reverse power relay B. bus disconnect link C. generator bus fuse connections D. power directional relay

Description : In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This is accomplished by opening the _____________. A. reverse power relay B. bus disconnect link C. generator bus fuse connections D. power directional relay

Last Answer : Answer: B