Making current of a circuit breaker refers to:

Making current of a circuit breaker refers to:

(1) Steady state rated current

(2) Average value of transient short circuit current

(3) R.M.S. value of the short circuit current at the the time of major peak

(4) Equal to the fault current
by

1 Answer

Answer :

Making current of a circuit breaker refers to: R.M.S. value of the short circuit current at the the time of major peak

by

Related questions

The interrupting time of a circuit breaker is the period between the instant of

Description : The interrupting time of a circuit breaker is the period between the instant of  (A) initiation of short circuit and the arc extinction on an opening operation (B) energizing of the trip circuit ... of primary arc contacts (D) energizing of the trip circuit and the parting of primary arc contacts

Last Answer : The interrupting time of a circuit breaker is the period between the instant of energizing of the trip circuit and the arc extinction on an opening operation

Out of the followings, which one is correct in case of a circuit breaker?

Description : Out of the followings, which one is correct in case of a circuit breaker? (1) Making capacity = 2.55 X braking capacity (2) Braking capacity = 2.55 X making capacity (3) Making capacity = 1.8 X braking capacity (4) Braking capacity = 1.8 X making capacity

Last Answer : Out of the followings, which one is correct in case of a circuit breaker? (1) Making capacity = 2.55 X braking capacity (2) Braking capacity = 2.55 X making capacity (3) Making capacity = 1.8 X braking capacity (4) Braking capacity = 1.8 X making capacity

Keeping in view the cost and overall effectiveness, the following circuit breaker is best suited for capacitor

Description : Keeping in view the cost and overall effectiveness, the following circuit breaker is best suited for capacitor bank switching.  A) Vacuum B) Air blast C) SF6 D) Oil

Last Answer : Keeping in view the cost and overall effectiveness, the following circuit breaker is best suited for capacitor bank switching.  A) Vacuum B) Air blast C) SF6 D) Oil

The Use of high speed circuit breakers

Description : The Use of high speed circuit breakers  A) Reduces the short circuit current B) Improves system stability C) Decreases system stability D) Increases the short circuit current

Last Answer : Q

Define the following terms related to circuit breaker. 1) Breaking Capacity 2) Making Capacity 3) Short time rating and 4) Normal current rating

Description : Define the following terms related to circuit breaker. 1) Breaking Capacity 2) Making Capacity 3) Short time rating and 4) Normal current rating

Last Answer : 1) Breaking Capacity: It is current (r.m.s) that a circuit breaker is capable of breaking at given recovery voltage under specified conditions (e.g. power factor, rate of rise of ... under specified conditions. The only limitation in this case is the temperature rise of current-carrying parts.

A 3-phase circuit breaker is rated at 1250 A, 2000 MVA, 33 kV, 4s. Its making current capacity will be

Description : A 3-phase circuit breaker is rated at 1250 A, 2000 MVA, 33 kV, 4s. Its making current capacity will be   (a) 35 kA (b) 89 kA (c) 79 kA (d) 69 kA

Last Answer : 89

Resistance switching is employed in

Description : Resistance switching is employed in  A) All breakers B)Bulk oil breakers C) Minimum oil breakers D) Air blast circuit breakers

Last Answer : Resistance switching is employed in  A) All breakers B)Bulk oil breakers C) Minimum oil breakers D) Air blast circuit breakers

In addition to testing the calibration of a circuit breaker, maintenance should include all of the following EXCEPT ______________. A. changing out of magnetic elements and thermal heaters yearly B. checking for corrosion, accumulation of dirt and thermal fatigue C. inspecting for loose or missing parts D. making sure foreign matter does not block tripping element

Description : In addition to testing the calibration of a circuit breaker, maintenance should include all of the following EXCEPT ______________. A. changing out of magnetic elements and thermal heaters yearly B. ... for loose or missing parts D. making sure foreign matter does not block tripping element

Last Answer : Answer: A

Making capacity of the circuit breaker depends on

Description : Making capacity of the circuit breaker depends on (A) operating voltage (B) short circuit MVA (C) fault current (D) All of the above

Last Answer : Making capacity of the circuit breaker depends on (A) operating voltage (B) short circuit MVA (C) fault current (D) All of the above

What is the making current capacity of a 3-phase breaker as derived from its symmetrical breaker capacity?

Description : What is the making current capacity of a 3-phase breaker as derived from its symmetrical breaker capacity? 

Last Answer : Making capacity = 2.55 times symmetrical breaking capacity.  

My current microwave oven causes my circuit breaker to trip if I use it at the same time as my toaster oven. Will this microwave solve that problem?

Description : My current microwave oven causes my circuit breaker to trip if I use it at the same time as my toaster oven. Will this microwave solve that problem?

Last Answer : It's doubtful; I wouldn't be able to answer that for sure unless I knew the particulars of your set-up (what is your microwave/toaster's draw? what kind of breaker do you have? etc.), but I don't see any reason why this microwave would help that situation.

A circuit breaker for a 300 KW alternator is rated at 470 amperes of full continuous load. The amount of overcurrent allowed is 125%. Which of the following conditions will trip the breaker? A. Sustained current flow of 470 amperes. B. Sustained current flow of 500 amperes for 10 minutes. C. Momentary starting load of 550 amperes. D. Sustained current flow of 590 amperes.

Description : A circuit breaker for a 300 KW alternator is rated at 470 amperes of full continuous load. The amount of overcurrent allowed is 125%. Which of the following conditions will trip the breaker? A. ... 10 minutes. C. Momentary starting load of 550 amperes. D. Sustained current flow of 590 amperes.

Last Answer : Answer: D

If a circuit breaker that utilizes built-in, current limiting fuses (CLF's) cannot be closed, the problem may be traced to __________. A. a blown CLF plunger holding the trip bar in the open position B. a missing CLF C. a misaligned limiter housing assembly D. all of the above

Description : If a circuit breaker that utilizes built-in, current limiting fuses (CLF's) cannot be closed, the problem may be traced to __________. A. a blown CLF plunger holding the trip bar in the open position B. a missing CLF C. a misaligned limiter housing assembly D. all of the above

Last Answer : Answer: D

During maintenance of circuit breakers, _______________. A. always smooth roughened contact surfaces with a file B. never pass more than rated breaker current through the overload heater element C. inspect for wear and misalignment of main contacts D. assume heater elements installed are of correct size

Description : During maintenance of circuit breakers, _______________. A. always smooth roughened contact surfaces with a file B. never pass more than rated breaker current through the overload heater element C. ... wear and misalignment of main contacts D. assume heater elements installed are of correct size

Last Answer : Answer: C

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

A reverse-current relay will prevent AC generator motorization by ____________. A. automatically redirecting the load B. automatically speeding up the prime mover C. tripping the panel board main switch D. tripping the generator circuit breaker

Description : A reverse-current relay will prevent AC generator motorization by ____________. A. automatically redirecting the load B. automatically speeding up the prime mover C. tripping the panel board main switch D. tripping the generator circuit breaker

Last Answer : Answer: D

You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0°. If you close the circuit breaker at this moment _____________. A. the incoming machine will accept all of the load B. the incoming machine will trip out on low voltage release C. a hazardous condition will be created by the cross current between the machines D. a hazardous condition will be created by the incoming machine being at a higher frequency than the bus

Description : You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0°. If you close the circuit breaker at this moment _____________. A. the incoming ... hazardous condition will be created by the incoming machine being at a higher frequency than the bus

Last Answer : Answer: C

You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0° prior to closing the circuit breaker. This indicates ___________. A. the frequency of the incoming machine is the same as the bus frequency B. the incoming machine is in phase with the bus, but the frequency is not the same C. the circuit breaker may be closed after breaker has been reset D. there is an existing cross current between generators

Description : You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0° prior to closing the circuit breaker. This indicates ___________. A. the frequency of ... be closed after breaker has been reset D. there is an existing cross current between generators

Last Answer : Answer: A

A circuit breaker and a fuse have a basic similarity in that they both _____________. A. can be reset to energize the circuit B. should open the circuit when overloaded C. will burn out when an over current flow develops D. all of the above

Description : A circuit breaker and a fuse have a basic similarity in that they both _____________. A. can be reset to energize the circuit B. should open the circuit when overloaded C. will burn out when an over current flow develops D. all of the above

Last Answer : Answer: B

Why asymmetrical breaking current is higher than the symmetrical breaking current in a circuit breaker?

Description : Why asymmetrical breaking current is higher than the symmetrical breaking current in a circuit breaker?

Last Answer : Asymmetrical breaking current is the rms value of the combined sum of the dc and ac components of the short circuit current at the instant of separation of the breaker contacts while ... the ac component alone. Thus asymmetrical breaking current is higher than the symmetrical breaking current.

Arc in a circuit breaker is interrupted at (a) zero current (b) maximum current (c) minimum voltage (d) maximum voltage

Description : Arc in a circuit breaker is interrupted at (a) zero current (b) maximum current (c) minimum voltage (d) maximum voltage

Last Answer : (a) zero current

The arc voltage produced in A.C. circuit breaker is always (a) in phase with the arc current (b) lagging the arc current by 90" (c) leading the arc current by 90° (d) none of the above

Description : The arc voltage produced in A.C. circuit breaker is always (a) in phase with the arc current (b) lagging the arc current by 90" (c) leading the arc current by 90° (d) none of the above

Last Answer : (a) in phase with the arc current

A circuit is disconnected by isolators when (a) line is energized (b) there is no current in the line (c) line is on full load (d) circuit breaker is not open

Description : A circuit is disconnected by isolators when (a) line is energized (b) there is no current in the line (c) line is on full load (d) circuit breaker is not open

Last Answer : (b) there is no current in the line

For a traction transformer circuit breaker state: 1) Rated current and rupturing capacity 2) Any two tests it should be capable of withstanding 3) Overall tripping time and relay time.

Description : For a traction transformer circuit breaker state: 1) Rated current and rupturing capacity 2) Any two tests it should be capable of withstanding 3) Overall tripping time and relay time.

Last Answer : Ans: 1) Rated current --- 750 A and Rupturing capacity --- 500 MVA  2) Any two tests it should be capable of withstanding --- Breaking test , Reclosing test , Endurance test ( any two )  3) Overall tripping time --- 0.14 sec and Relay time --- 0.04 sec 

A three-phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3 s. The symmetrical breaking current is

Description : A three-phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3 s. The symmetrical breaking current is  (A) 1200 A (B) 3600 A (C) 35 kA (D) 104.8 kA

Last Answer : A three-phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3 s. The symmetrical breaking current is 35 kA 

Electrical jellies! Got a circuit breaker (home) that has popped and won't reset. Suggestions?

Description : Electrical jellies! Got a circuit breaker (home) that has popped and won't reset. Suggestions?

Last Answer : My husband, who was a master electrician, said you need to call a professional. You either have a bad breaker or the breaker that refuses to reset is saving your life because you have a dead short some place and your house would burn down if ithe breaker wasn’t tripped.

My (soon-to-be-replaced) air conditioner is frequently tripping the circuit breaker in my apartment. What can I do to prevent this?

Description : My (soon-to-be-replaced) air conditioner is frequently tripping the circuit breaker in my apartment. What can I do to prevent this?

Last Answer : answer:A mini-split AC unit will use less power than a regular square version and should help with the problem. However if your problem resides in old wiring with a lower amperage/threshold you might ... every time you want to use it but this has cut my electric bill dramatically. Hope this helps

What is the difference between a fuse and a circuit breaker ?

Description : What is the difference between a fuse and a circuit breaker ?

Last Answer : Fuse : It is a type of soft metal wire which, when more than the required current flows through the wire, burns it, disconnects the electrical circuit from the source and protects the valuable ... or fault in the power supply line . This breaks the static contact and protects it from accidents.

Why is the circuit breaker turned off automatically ?

Description : Why is the circuit breaker turned off automatically ?

Last Answer : Circuit breakers are automatically turned off to protect electrical equipment from damage. An automatic switch is used to protect the electrical circuit or electrical equipment from damage due to ... is stopped and the electrical equipment connected to the circuit is protected from damage.

What is Earth Leakage Circuit Breaker ?

Description : What is Earth Leakage Circuit Breaker ?

Last Answer : Earth leakage circuit breaker is a protective device which protects the leaky faulty or faulty circuit from dangerous parts by separating it from the good parts. The leakage current of the circuit flows ... a faulty place due to a leakage error in the circuit is called a leakage circuit breaker.

What is an Air Circuit Breaker ?

Description : What is an Air Circuit Breaker ?

Last Answer : Air circuit breaker is a circuit breaker which is controlled by air, that is, a breaker which is turned on by air pressure and turned off by air pressure .

What is Oil Circuit Breaker ?

Description : What is Oil Circuit Breaker ?

Last Answer : An oil circuit breaker is a circuit breaker that contains oil and is in operation or on-off insulation oil . The oil used in the oil circuit breaker acts as insulation and extinguishes the arc. ... types. A) Plain brake type bulk oil circuit breaker and b) Arc controlled bulk oil circuit breaker.

What is a circuit breaker ?

Description : What is a circuit breaker ?

Last Answer : When excessive current flows in any faulty circuit , it is called circuit breaker which disconnects automatically or automatically.

What is the reason for using circuit breaker in circuit ?

Description : What is the reason for using circuit breaker in circuit ?

Last Answer : Circuit breakers are used for safety.

What is the function of circuit breaker ?

Description : What is the function of circuit breaker ?

Last Answer : Used to stop excessive flow

What are the common sizes of circuit breaker panel for all electrical home?

Description : What are the common sizes of circuit breaker panel for all electrical home?

Last Answer : 200 amp is the most common size used in most homes.

Why will too many electrical devices operating at one time after blow a fuse or trip a circuit breaker?

Description : Why will too many electrical devices operating at one time after blow a fuse or trip a circuit breaker?

Last Answer : The load exceeds the limit of the breaker or fuse. For example a20 amp breaker on a 120 volt circuit will handle 2400 watts. Exceedthat wattage and the breaker will trip or the fuse will blow.

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

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

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

As shown in the illustration, 'B' is a ____________. EL-0058 A. single-pole, double-throw switch B. double-pole, single-throw switch C. double-pole, double-throw switch D. circuit breaker

Description : As shown in the illustration, 'B' is a ____________. EL-0058 A. single-pole, double-throw switch B. double-pole, single-throw switch C. double-pole, double-throw switch D. circuit breaker

Last Answer : Answer: C