What are the characteristics of CB, OLR and HRC Fuse?

What are the characteristics of CB, OLR and HRC Fuse?
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When CB is used the CB characteristics should be below the fuse, because the CB should operate first and then fuse. Not vice-versa. Because CB is the main protection or main breaking device.  

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Description : In the lighting distribution circuit shown in the illustration, if all switches are closed and fuse 'F2' were to open, all lights on branches ____________. EL-0013 A. '1', '2', and '3' would go out B. '1' ... and '3' would burn dimly D. '1' and '3' would go out, while branch '2' would remain lit

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Last Answer : Answer: D

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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

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When testing for blown fuses in a three-phase supply circuit to a motor, you should first ___________________. A. apply the megger across the tops of the line fuses B. apply an ammeter diagonally across the top of the first line fuse and the bottom of the third line fuse C. apply the voltage tester across the bottoms of the line fuses D. ensure the circuit is de-energized, and then use a continuity tester

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Last Answer : Answer: D

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

In the illustration if BRANCH NO. 1 is a lighting circuit for crew's berthing, Federal Regulations (46 CFR) require the maximum fuse rating for that branch to be _________. EL-0013 A. 80% of the connected load B. 15 amps C. 20 amps D. 30 amps

Description : In the illustration if BRANCH NO. 1 is a lighting circuit for crew's berthing, Federal Regulations (46 CFR) require the maximum fuse rating for that branch to be _________. EL-0013 A. 80% of the connected load B. 15 amps C. 20 amps D. 30 amps

Last Answer : Answer: C

In the illustrated motor controller, the motor fails to start. A voltmeter reading between 1 and 6 reads line voltage, while the voltmeter reading between 2 and 6 reads 0 VAC. The problem is __________. EL-0007 A. the control fuse is the wrong amperage not allowing full current to pass through B. the stop switch is open C. an open in the 'M' coil, 'Ma' contact/start switch or overload contacts D. fuse '10a' is blown

Description : In the illustrated motor controller, the motor fails to start. A voltmeter reading between 1 and 6 reads line voltage, while the voltmeter reading between 2 and 6 reads 0 VAC. The problem is __________. EL- ... in the 'M' coil, 'Ma' contact/start switch or overload contacts D. fuse '10a' is blown

Last Answer : Answer: B

A circuit with a blown fuse would be described as a/an _____________. A. short circuit B. open circuit C. bonded circuit D. grounded circuit

Description : A circuit with a blown fuse would be described as a/an _____________. A. short circuit B. open circuit C. bonded circuit D. grounded circuit

Last Answer : Answer: B

A fuse will 'blow' if _____________. A. an electric motor is stopped suddenly by opening a switch B. the flow of current to the protection device is reversed C. the electrical current exceeds the rated value of the fuse D. unequal resistors are connected in parallel

Description : A fuse will 'blow' if _____________. A. an electric motor is stopped suddenly by opening a switch B. the flow of current to the protection device is reversed C. the electrical current exceeds the rated value of the fuse D. unequal resistors are connected in parallel

Last Answer : Answer: C

In addition to short circuits and sustained overloads, fuses are likely to blow due to _____________. A. loose fuse clips B. low ambient temperatures C. low contact resistance D. all of the above

Description : In addition to short circuits and sustained overloads, fuses are likely to blow due to _____________. A. loose fuse clips B. low ambient temperatures C. low contact resistance D. all of the above

Last Answer : Answer: A

In the illustration if BRANCH NO. 1 is a lighting circuit for crew's berthing, 46 CFR requires the maximum fuse rating for that branch to be _________. EL-0013 A. 15 amps B. 80% of the connected load C. 20 amps D. 30 amps

Description : In the illustration if BRANCH NO. 1 is a lighting circuit for crew's berthing, 46 CFR requires the maximum fuse rating for that branch to be _________. EL-0013 A. 15 amps B. 80% of the connected load C. 20 amps D. 30 amps

Last Answer : Answer: C

Using a fuse whose rating is higher than necessary ________. A. endangers the apparatus it is supposed to protect B. reduces the possibility of short circuits C. increases the efficiency of the equipment by allowing more current to be used D. wastes money because they are more expensive

Description : Using a fuse whose rating is higher than necessary ________. A. endangers the apparatus it is supposed to protect B. reduces the possibility of short circuits C. increases the efficiency of the equipment by allowing more current to be used D. wastes money because they are more expensive

Last Answer : Answer: A

In the illustration, 'D' is the symbol for a/an __________. EL-0005 A. thermal overload heater B. portable cable C. fuse D. indicating lamp

Description : In the illustration, 'D' is the symbol for a/an __________. EL-0005 A. thermal overload heater B. portable cable C. fuse D. indicating lamp

Last Answer : Answer: C

If a fuse of correct size and type blows frequently, ________________. A. try the next higher amperage rating B. try the next lower amperage rating C. look for trouble within the circuit D. reduce the applied voltage 10%

Description : If a fuse of correct size and type blows frequently, ________________. A. try the next higher amperage rating B. try the next lower amperage rating C. look for trouble within the circuit D. reduce the applied voltage 10%

Last Answer : Answer: C

A fuse will blow for all the listed reasons EXCEPT ________. A. excessive vibration B. extremely hot surroundings C. loose fuse clips D. low contact resistance within the fuse

Description : A fuse will blow for all the listed reasons EXCEPT ________. A. excessive vibration B. extremely hot surroundings C. loose fuse clips D. low contact resistance within the fuse

Last Answer : Answer: D

When troubleshooting a motor controller, all indications are that a relay coil should be energized. If there were no magnetic pull, with rated voltage measured across the coil, the most probable cause would be that the _________________. A. coil is open B. control fuse is open C. auxiliary contact in series with the coil is defective D. relay armature is stuck

Description : When troubleshooting a motor controller, all indications are that a relay coil should be energized. If there were no magnetic pull, with rated voltage measured across the coil, the most probable cause ... open C. auxiliary contact in series with the coil is defective D. relay armature is stuck

Last Answer : Answer: A

When replacing fuses, always make sure _______________. A. to stand on a rubber mat and use rubber gloves B. to use insulated pliers or screwdriver C. the fuse clips are straight, tight, and in good contact D. to increase the fuse rating 10% to guard against 'nuisance blowing'

Description : When replacing fuses, always make sure _______________. A. to stand on a rubber mat and use rubber gloves B. to use insulated pliers or screwdriver C. the fuse clips are straight, tight, and in good contact D. to increase the fuse rating 10% to guard against 'nuisance blowing'

Last Answer : Answer: C

When troubleshooting motor controllers, a shorted relay or contactor coil is often indicated by _______________. A. a resistance reading of 'infinity' on an ohmmeter B. charred insulation and/or a blown control fuse C. a reading of 'zero' on a megger from one of the coil's leads to ground D. a higher-than-normal voltage reading across the winding

Description : When troubleshooting motor controllers, a shorted relay or contactor coil is often indicated by _______________. A. a resistance reading of 'infinity' on an ohmmeter B. charred insulation and/or a blown ... of the coil's leads to ground D. a higher-than-normal voltage reading across the winding

Last Answer : Answer: B

You are using a mechanical voltage tester to check the fuses in a three-phase circuit supplying an electric motor. For which of the following reasons must the motor be stopped during the test? A. Testing an energized circuit presents a hazard to the testing personnel. B. A faulty fuse could go undetected with the motor energized. C. Reversed polarity of the circuit would be indicated by the voltage tester with the circuit energized. D. All of the above.

Description : You are using a mechanical voltage tester to check the fuses in a three-phase circuit supplying an electric motor. For which of the following reasons must the motor be stopped during the test? A. ... circuit would be indicated by the voltage tester with the circuit energized. D. All of the above.

Last Answer : Answer: B

If the motor fails to start and a voltmeter reading between 1 and 6, as illustrated, indicates line voltage, your next step should be to ________. EL-0007 A. replace fuse '10a' B. replace or repair contact 'Ma' C. reset and determine the cause of the overload D. check line voltage between L1 and L3

Description : If the motor fails to start and a voltmeter reading between 1 and 6, as illustrated, indicates line voltage, your next step should be to ________. EL-0007 A. replace fuse '10a' B. replace or repair contact 'Ma' C. reset and determine the cause of the overload D. check line voltage between L1 and L3

Last Answer : Answer: C

An instantaneous-trip-type fuse will _____________. A. open as soon as the load current exceeds its set point B. allow a preset delay between overcurrent and melting C. open a circuit by using a time delay element with a magnetic trip D. reset itself when the overcurrent is corrected

Description : An instantaneous-trip-type fuse will _____________. A. open as soon as the load current exceeds its set point B. allow a preset delay between overcurrent and melting C. open a circuit by using a time delay element with a magnetic trip D. reset itself when the overcurrent is corrected

Last Answer : Answer: A

Component 'C' in section 'I' shown in the illustration represent ____________. EL-0093 A. a selectable holding coil arrangement B. a 'fuse blown' indicator circuit C. 'reset' and 'trouble' lamps D. a handset with switch and voice elements

Description : Component 'C' in section 'I' shown in the illustration represent ____________. EL-0093 A. a selectable holding coil arrangement B. a 'fuse blown' indicator circuit C. 'reset' and 'trouble' lamps D. a handset with switch and voice elements

Last Answer : Answer: D

Which of the following conditions is most likely to occur if a single element fuse were used to replace a blown dual element fuse in a motor controller circuit? A. The fuse will blow when the motor is started. B. The fuse works, but overheats at high motor loads. C. The motor runs at reduced voltage. D. The motor runs normally.

Description : Which of the following conditions is most likely to occur if a single element fuse were used to replace a blown dual element fuse in a motor controller circuit? A. The fuse will blow when the motor ... overheats at high motor loads. C. The motor runs at reduced voltage. D. The motor runs normally.

Last Answer : Answer: A