Why breaker tripping is prohibited on very low pressure?

Why breaker tripping is prohibited on very low pressure?  
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1 Answer

Answer :

The efficiency with which the arc quenching is taking place in the breaker depends on the air pressure. So if the air pressure is low effective arc quenching will not take place which will result in damage of CB. Hence the tripping of the breaker at very low air pressure is prevented.  
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Related questions

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

Component F in the illustrated device is for _________. EL-0033 A. short circut protection B. latching the trip unit closed after resetting the breaker C. overload protection D. providing a flexible connection between the input terminal G and the tripping unit E

Description : Component F in the illustrated device is for _________. EL-0033 A. short circut protection B. latching the trip unit closed after resetting the breaker C. overload protection D. providing a flexible connection between the input terminal G and the tripping unit E

Last Answer : Answer: C

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

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

The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____________. A. designing the contacts to open slowly B. directing the arc into an arc chute C. an inverse timed thermal trip for short circuit currents D. instantaneous magnetic trip for overload currents

Description : The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____________. A. designing the contacts to open slowly B. directing the arc into an ... an inverse timed thermal trip for short circuit currents D. instantaneous magnetic trip for overload currents

Last Answer : Answer: B

Why does our GFCI breaker keep tripping?

Description : Why does our GFCI breaker keep tripping?

Last Answer : More details, please. What appliances are connected to the outlet(s) on this circuit?

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

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 

The purpose of a short circuit forcing module (short time trip) installed in a branch line is to provide ____________. A. high speed clearance of low impedance short circuits in the branch B. continuity of service on main bus under short circuit conditions in a branch C. isolation of short circuits by selective tripping of branch circuit breakers D. all of the above

Description : The purpose of a short circuit forcing module (short time trip) installed in a branch line is to provide ____________. A. high speed clearance of low impedance short circuits in the branch B. ... C. isolation of short circuits by selective tripping of branch circuit breakers D. all of the above

Last Answer : Answer: D

The timer element of a reverse power relay cannot be energized unless _____________. A. the power flow is the same as the tripping direction B. the power flow is the opposite to the tripping direction C. the movement of the disk is damped by a permanent magnet D. one generator is motorized

Description : The timer element of a reverse power relay cannot be energized unless _____________. A. the power flow is the same as the tripping direction B. the power flow is the opposite to the tripping direction C. the movement of the disk is damped by a permanent magnet D. one generator is motorized

Last Answer : Answer: A

The timer element of a reverse power relay cannot be energized unless _____________. A. one generator is fully motorized B. the movement of the disk is damped by a permanent magnet C. the power flow is the same as the tripping direction D. the power flow is the opposite to the tripping direction

Description : The timer element of a reverse power relay cannot be energized unless _____________. A. one generator is fully motorized B. the movement of the disk is damped by a permanent magnet C. the power flow is the same as the tripping direction D. the power flow is the opposite to the tripping direction

Last Answer : Answer: C

Why under voltage tripping of motor is incorporated in motor feeder breakers?

Description : Why under voltage tripping of motor is incorporated in motor feeder breakers? 

Last Answer : The under voltage can occur in case of bus fault. If the motors are kept connected they will feed the fault which may cause the damage. Due to the back feeding from the motor the motor will slow down ... case pht motor will not rotate for the designed 3 minute period in case of bus under voltage).  

Undervoltage trips are frequently installed on switchboard circuit breakers to trip ____________. A. out generators in the event of severe arcing or sparking B. out generators when there is reversal of power in the main circuit C. the breaker if the generator overspeeds by 5%, but continues to run D. out generators when there is low voltage in the main circuit

Description : Undervoltage trips are frequently installed on switchboard circuit breakers to trip ____________. A. out generators in the event of severe arcing or sparking B. out generators when there is reversal of power ... , but continues to run D. out generators when there is low voltage in the main circuit

Last Answer : Answer: D

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

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

The purpose of a main switchboard circuit breaker's reverse-power trip is to _____________. A. prevent main circuit overload B. protect the circuit breaker blowout coil C. prevent alternator motorization D. prevent low voltage tripout

Description : The purpose of a main switchboard circuit breaker's reverse-power trip is to _____________. A. prevent main circuit overload B. protect the circuit breaker blowout coil C. prevent alternator motorization D. prevent low voltage tripout

Last Answer : Answer: C

Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly fluctuating temperatures, an ambient compensating element must be used. This element consists of a ______________. A. cylindrical spring on the contact arm B. conical spring on the contact arm C. second bimetal element D. second electromagnet

Description : Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly fluctuating temperatures, an ambient compensating element must be used. This element consists of ... arm B. conical spring on the contact arm C. second bimetal element D. second electromagnet

Last Answer : Answer: C

Tripping on three tablespoons of nutmeg?

Description : Tripping on three tablespoons of nutmeg?

Last Answer : answer:Eating nutmeg to trip is a myth. You have to smoke it.

Any advice for road-tripping around Vancouver Island, British Columbia, Canada?

Description : Any advice for road-tripping around Vancouver Island, British Columbia, Canada?

Last Answer : answer:Write to the Parks of course; but, It would be wise to take a fast course in French with a touring book. It would make the trip fun. Here are some camping sites that might be good: ... .pc.gc.ca/voyage-travel/reserve/index_e.asp http://www.pccamping.ca/parkscanada/ http://camping-canada.com/

What are some good/irritating tongue twisters that you know & can you say any without tripping up?

Description : What are some good/irritating tongue twisters that you know & can you say any without tripping up?

Last Answer : answer:Big black rubber baby buggy bumpers. She sells sea shells by the sea shore No, I can’t actually say them without tripping over my tongue. Fortunately, I don’t feel that my life is diminished in any way by not saying them, so I’m good!

If you have a dream about walking to school and tripping at the crosswalk An example of the latent meaning of the dream might be?

Description : If you have a dream about walking to school and tripping at the crosswalk An example of the latent meaning of the dream might be?

Last Answer : You are frightened about moving ahead in life - Apex

If you have a dream about walking to school and tripping at the crosswalk An example of the latent meaning of the dream might be?

Description : If you have a dream about walking to school and tripping at the crosswalk An example of the latent meaning of the dream might be?

Last Answer : You are frightened about moving ahead in life - Apex

What is the safe maximum tripping speed of a turbine operating at 2500 rpm?

Description : What is the safe maximum tripping speed of a turbine operating at 2500 rpm?

Last Answer : The rule is to trip at 10 percent overspeed. Therefore, 2500 x 1.10 = 2750 rpm.

. If the power distribution system shown in figure 2-22 uses selective tripping, what is the time delay rating for each of the circuit breakers shown?

Description : . If the power distribution system shown in figure 2-22 uses selective tripping, what is the time delay rating for each of the circuit breakers shown?

Last Answer : CB1-long time delay; CB2, CB3-short time delay; CB4 through

What is selective tripping and why is it used?

Description : What is selective tripping and why is it used?

Last Answer : . It is the use of time delay ratings to cause the circuit breaker closest to the faulty circuit to trip. This isolates the faulty circuit without affecting other circuits.

Routine maintenance of dry-type transformers should include ____________. A. cleaning the windings, if accessible, with a vacuum cleaner or very low pressure air B. measuring and recording the winding temperature with an accurate mercury thermometer C. periodic cleaning of the winding insulation with an approved solvent D. making sure that the units are close to bulkheads or corners to protect them from damage

Description : Routine maintenance of dry-type transformers should include ____________. A. cleaning the windings, if accessible, with a vacuum cleaner or very low pressure air B. measuring and recording the winding ... . making sure that the units are close to bulkheads or corners to protect them from damage

Last Answer : Answer: A

Which of the following busbar arrangement is generally employed in distribution system: a) One-and-half breaker arrangement b) Main and transfer arrangement c) Ring main distribution system d) Single busbar arrangement system

Description : Which of the following busbar arrangement is generally employed in distribution system: a) One-and-half breaker arrangement b) Main and transfer arrangement c) Ring main distribution system d) Single busbar arrangement system

Last Answer : Ans: C

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

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

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

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

If an electric motor fails to start, you should FIRST check the _____________. A. phase sequence B. ampere load C. fuse or circuit breaker D. line frequency

Description : If an electric motor fails to start, you should FIRST check the _____________. A. phase sequence B. ampere load C. fuse or circuit breaker D. line frequency

Last Answer : Answer: C

To remove an alternator operating in parallel with another unit from the main electrical bus, you must FIRST _________. A. adjust the power factor on both units B. set the desired voltage on the outgoing alternator C. open the circuit breaker on the outgoing alternator D. remove the load from the outgoing alternator

Description : To remove an alternator operating in parallel with another unit from the main electrical bus, you must FIRST _________. A. adjust the power factor on both units B. set the desired voltage on ... C. open the circuit breaker on the outgoing alternator D. remove the load from the outgoing alternator

Last Answer : Answer: D

Attempting to parallel an AC generator which is out of phase with the bus will result in which of the following problems? A. The breaker should trip. B. The KVA will decrease. C. The synchronizing lamps will burn out. D. The power factor will be unitized.

Description : Attempting to parallel an AC generator which is out of phase with the bus will result in which of the following problems? A. The breaker should trip. B. The KVA will decrease. C. The synchronizing lamps will burn out. D. The power factor will be unitized.

Last Answer : Answer: A

After closing the circuit breaker to place two similar alternators in parallel, the NEXT step is to balance the _____________. A. power factor B. voltage load C. kilowatt load D. ampere load

Description : After closing the circuit breaker to place two similar alternators in parallel, the NEXT step is to balance the _____________. A. power factor B. voltage load C. kilowatt load D. ampere load

Last Answer : Answer: C

When an AC or a DC motor fails to start, the FIRST step in troubleshooting should be to check the ____________. A. motor windings for obvious opens B. motor controller leads for continuity C. fuse or circuit breaker D. motor controller leads for grounds

Description : When an AC or a DC motor fails to start, the FIRST step in troubleshooting should be to check the ____________. A. motor windings for obvious opens B. motor controller leads for continuity C. fuse or circuit breaker D. motor controller leads for grounds

Last Answer : Answer: C

An alternator is being paralleled with one on the line. At the INSTANT the circuit breaker is closed, the frequency of the incoming alternator will normally _____________. A. increase B. not change C. decrease D. be exactly 60 hertz

Description : An alternator is being paralleled with one on the line. At the INSTANT the circuit breaker is closed, the frequency of the incoming alternator will normally _____________. A. increase B. not change C. decrease D. be exactly 60 hertz

Last Answer : Answer: C

Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine _____________. A. slightly less than the line frequency B. the same as the line frequency C. slightly greater than the line frequency D. all of the above

Description : Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine _____________. A. slightly less than the line frequency B. the same as the line frequency C. slightly greater than the line frequency D. all of the above

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