For routine cleaning of a commutator, you should apply _____________. A. course sandpaper in a slow back and forth motion across the commutator slots B. an emery cloth parallel to the axis of the machine C. a canvas wiper to the machine while running D. cotton swabs between the commutator bars

For routine cleaning of a commutator, you should apply _____________. A. course sandpaper in a slow back and forth motion across the commutator slots B. an emery cloth parallel to the axis of the machine C. a canvas wiper to the machine while running D. cotton swabs between the commutator bars
by

1 Answer

Answer :

Answer: C
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Related questions

Seating the brushes on a D.C. motor is first accomplished using ________________. A. a file for cutting the approximate curvature followed by sandpaper for the final fit B. sandpaper with the motor not operating and then a seating stone while running the machine C. emery paper for the initial cut and crocus cloth for the finishing cut D. course lapping compound, followed by a medium and then a fine grade

Description : Seating the brushes on a D.C. motor is first accomplished using ________________. A. a file for cutting the approximate curvature followed by sandpaper for the final fit B. sandpaper with the motor not ... for the finishing cut D. course lapping compound, followed by a medium and then a fine grade

Last Answer : Answer: B

All of the following items can be used in the maintenance of a D.C. propulsion motor's commutator EXCEPT _______________. A. a canvas wiper B. safety solvent C. abrasive dressing stones D. sandpaper

Description : All of the following items can be used in the maintenance of a D.C. propulsion motor's commutator EXCEPT _______________. A. a canvas wiper B. safety solvent C. abrasive dressing stones D. sandpaper

Last Answer : Answer: B

Which of the following materials is recommended for finishing the slip rings after grinding or turning? A. grade 00 sandpaper B. canvas wiper C. crocus cloth D. smooth file

Description : Which of the following materials is recommended for finishing the slip rings after grinding or turning? A. grade 00 sandpaper B. canvas wiper C. crocus cloth D. smooth file

Last Answer : Answer: C

To effectively clean a commutator in good physical condition, you should use ____________. A. trichloride ethylene B. kerosene C. a canvas wiper D. a commutator stone

Description : To effectively clean a commutator in good physical condition, you should use ____________. A. trichloride ethylene B. kerosene C. a canvas wiper D. a commutator stone

Last Answer : Answer: C

Which of the following statements represents the FIRST step in seating new brushes on slip rings? A. Wrap sandpaper around the slip rings and slide it back and forth between the brushes and the slip rings. B. Press the brushes against the slip ring with a wood block. C. Increase brush pressure and run at no load for 3 to 4 hours. D. Apply seating compound under the brushes and run at no load for 2 hours.

Description : Which of the following statements represents the FIRST step in seating new brushes on slip rings? A. Wrap sandpaper around the slip rings and slide it back and forth between the brushes and the slip rings. B. ... to 4 hours. D. Apply seating compound under the brushes and run at no load for 2 hours.

Last Answer : Answer: A

A flickering ground detection lamp on a DC system would indicate a _____________. A. multiple-ground condition in the distribution system B. ground in an armature coil of an operating machine C. ground in a motor accompanied with a short D. short between two adjacent bars of the generator commutator

Description : A flickering ground detection lamp on a DC system would indicate a _____________. A. multiple-ground condition in the distribution system B. ground in an armature coil of an operating machine C. ground in a motor accompanied with a short D. short between two adjacent bars of the generator commutator

Last Answer : Answer: B

Number of commutator bars for a 4-pole, 2-layer, DC lap winding with 24 slots and one conductor per layer is

Description : Number of commutator bars for a 4-pole, 2-layer, DC lap winding with 24 slots and one conductor per layer is (A) 48 (B) 24 (C) 192 (D) 96

Last Answer : Number of commutator bars for a 4-pole, 2-layer, DC lap winding with 24 slots and one conductor per layer is 24

In addition to undercutting the mica, proper maintenance of a D.C. motor's commutator includes _______________. A. side-cutting the copper segments and insulating the slots B. coating the copper surface with light machine oil for the first four hours of operation C. baking the armature in an oven at a maximum of 95°C for not over 8 hours D. all of the above

Description : In addition to undercutting the mica, proper maintenance of a D.C. motor's commutator includes _______________. A. side-cutting the copper segments and insulating the slots B. coating the copper surface with light machine ... in an oven at a maximum of 95°C for not over 8 hours D. all of the above

Last Answer : Answer: A

To properly seat the brushes on slip rings, you should use ____________. A. sand paper B. crocus cloth C. emery cloth D. all of the above

Description : To properly seat the brushes on slip rings, you should use ____________. A. sand paper B. crocus cloth C. emery cloth D. all of the above

Last Answer : Answer: A

Temporary repairs to an open DC propulsion armature coil can be made by _____________. A. connecting the coil ends directly to a pair of negative brushes B. disconnecting coil ends, insulating each, and short circuiting the two commutator bars C. grounding the coil ends and short circuiting the commutator bar D. removing the sparking brushes

Description : Temporary repairs to an open DC propulsion armature coil can be made by _____________. A. connecting the coil ends directly to a pair of negative brushes B. disconnecting coil ends, insulating ... C. grounding the coil ends and short circuiting the commutator bar D. removing the sparking brushes

Last Answer : Answer: B

Sometimes it's necessary, but why should you avoid using cotton swabs when cleaning a magnetic tape transport?

Description : Sometimes it's necessary, but why should you avoid using cotton swabs when cleaning a magnetic tape transport?

Last Answer : Cotton swabs are not lint free.

In D.C. motor construction, the armature coils' ends are _______________. A. soldered to the commutator bar risers B. imbedded into core slots C. crimped together with brush pigtails D. spliced with the field windings

Description : In D.C. motor construction, the armature coils' ends are _______________. A. soldered to the commutator bar risers B. imbedded into core slots C. crimped together with brush pigtails D. spliced with the field windings

Last Answer : Answer: A

Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness? A. Fill the motor housing with CO2 to inert the space. B. Strap silica gel around the commutator. C. Place heat lamps in the motor housings. D. Cover the equipment with a canvas tarpaulin.

Description : Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness? A. Fill the motor housing with CO2 to inert the space. B. Strap ... C. Place heat lamps in the motor housings. D. Cover the equipment with a canvas tarpaulin.

Last Answer : Answer: C

A short in the shunt field of a DC motor is best located by _____________. A. visual inspection of the commutator B. applying AC voltage to each field coil and measuring the voltage drop across each field coil C. using a growler and hacksaw blade D. isolating each coil from the others and using a megohmmeter

Description : A short in the shunt field of a DC motor is best located by _____________. A. visual inspection of the commutator B. applying AC voltage to each field coil and measuring the voltage drop across ... using a growler and hacksaw blade D. isolating each coil from the others and using a megohmmeter

Last Answer : Answer: B

Sparking at the brushes of a running motor could be an indication of _____________. A. normal operation B. a dirty commutator C. increased brush capacity D. water vapor absorption

Description : Sparking at the brushes of a running motor could be an indication of _____________. A. normal operation B. a dirty commutator C. increased brush capacity D. water vapor absorption

Last Answer : Answer: B

Oxide layer formed on the non-ferrous metal surface after its annealing is (A) Removed by acid pickling (B) Hammered into the surface (C) Removed with coarse emery cloth

Description : Oxide layer formed on the non-ferrous metal surface after its annealing is (A) Removed by acid pickling (B) Hammered into the surface (C) Removed with coarse emery cloth

Last Answer : Option A

A shunt-wound DC generator is one in which the shunt field windings are in parallel with the _____________. A. commutator B. brushes C. armature D. all of the above

Description : A shunt-wound DC generator is one in which the shunt field windings are in parallel with the _____________. A. commutator B. brushes C. armature D. all of the above

Last Answer : Answer: D

If the pointer of the synchroscope is rotating in the slow direction when you are preparing to parallel two alternators, the _____________. A. incoming machine is turning faster than the load alternator B. loaded alternator is turning faster than the incoming machine C. load on the loaded alternator is ready to split D. incoming machine is beginning to pick up some of the load

Description : If the pointer of the synchroscope is rotating in the slow direction when you are preparing to parallel two alternators, the _____________. A. incoming machine is turning faster than the load alternator B ... alternator is ready to split D. incoming machine is beginning to pick up some of the load

Last Answer : Answer: B

You are attempting to parallel two AC generators and the synchroscope pointer is revolving in the slow direction. This indicates that the frequency of the incoming machine is _____________. A. higher than the bus frequency B. lower than the bus frequency C. the same as the bus frequency but out of phase with it D. the same as the bus frequency, and the circuit breaker may be closed at any pointer position

Description : You are attempting to parallel two AC generators and the synchroscope pointer is revolving in the slow direction. This indicates that the frequency of the incoming machine is _____________. A. higher than ... same as the bus frequency, and the circuit breaker may be closed at any pointer position

Last Answer : Answer: B

Which of the following represents the accepted method of cleaning dust and foreign particles from electrical equipment while limiting damage to electric components? A. Carefully wiping off the components with a soft cotton rag. B. Blowing a high velocity stream of compressed air rapidly across the components. C. Using a vacuum cleaner to remove debris from the components. D. Using carbon tetrachloride as a cleaning solvent to clean the components.

Description : Which of the following represents the accepted method of cleaning dust and foreign particles from electrical equipment while limiting damage to electric components? A. Carefully wiping off the components ... the components. D. Using carbon tetrachloride as a cleaning solvent to clean the components.

Last Answer : Answer: C

Which of the listed conditions might contribute to very rapid wearing of a DC machine's commutator bars? A. A grounded commutator bar B. Using improper carbon brushes C. Aligning the front and rear mica V-rings improperly D. An open circuit in the armature

Description : Which of the listed conditions might contribute to very rapid wearing of a DC machine's commutator bars? A. A grounded commutator bar B. Using improper carbon brushes C. Aligning the front and rear mica V-rings improperly D. An open circuit in the armature

Last Answer : Answer: B

17 Uncommon Uses for Cotton Swabs

Description : 17 Uncommon Uses for Cotton Swabs

Last Answer : In the field of cleaning ears, no household item is relied upon more than cotton swabs. The swabs, tipped with cotton sheets, are built to remove earwax and dirt, which results in better ... swab's thin ends, along with their cotton-covered surfaces, can access your jewelry's tiniest corners.

When cleaning the parts of a tape transport, why should you switch lint-free cloths and swabs often?

Description : When cleaning the parts of a tape transport, why should you switch lint-free cloths and swabs often?

Last Answer : You may transfer dirt or oxide particles from one part of the tape transport to another

To repair a small electrical motor that has been submerged in saltwater, you should _____________. A. wash it with fresh water and apply an external source of heat B. renew the windings C. send it ashore to an approved service facility D. rinse all electrical parts with a carbon tetrachloride cleaning solvent and then blow dry the motor with compressed air

Description : To repair a small electrical motor that has been submerged in saltwater, you should _____________. A. wash it with fresh water and apply an external source of heat B. renew the windings ... electrical parts with a carbon tetrachloride cleaning solvent and then blow dry the motor with compressed air

Last Answer : Answer: A

The rotor slots of a repulsion-type motor are generally skewed (placed nonparallel to the rotor axis) to _________. A. produce a constant starting torque B. permit a greater air gap with the starter C. permit a smaller air gap with the starter D. reduce eddy current losses

Description : The rotor slots of a repulsion-type motor are generally skewed (placed nonparallel to the rotor axis) to _________. A. produce a constant starting torque B. permit a greater air gap with the starter C. permit a smaller air gap with the starter D. reduce eddy current losses

Last Answer : Answer: A

If the energy input is significantly reduced to the prime mover of one shipboard alternator operating in parallel with others, that alternator will _____________. A. continue to operate at no load B. lose its load and overspeed C. begin to motorize and then trip out D. slow down and operate at reduced load

Description : If the energy input is significantly reduced to the prime mover of one shipboard alternator operating in parallel with others, that alternator will _____________. A. continue to operate at no load B. lose ... overspeed C. begin to motorize and then trip out D. slow down and operate at reduced load

Last Answer : Answer: C

If field excitation is suddenly lost to an alternator operating in parallel, that alternator will _____________. A. supply excessive current to the bus B. operate at the same load, but with reduced voltage C. lose its load and tend to overspeed D. become overloaded and slow down

Description : If field excitation is suddenly lost to an alternator operating in parallel, that alternator will _____________. A. supply excessive current to the bus B. operate at the same load, but with reduced voltage C. lose its load and tend to overspeed D. become overloaded and slow down

Last Answer : Answer: C

Routine A.C. motor maintenance should include periodic ______________. A. thermometer readings at normal loads to detect abnormal temperature rises B. inspection of the motor's internals for loose rotor bars or field poles C. bearing replacement each year using sealed units if available D. all of the above

Description : Routine A.C. motor maintenance should include periodic ______________. A. thermometer readings at normal loads to detect abnormal temperature rises B. inspection of the motor's internals for loose rotor bars ... C. bearing replacement each year using sealed units if available D. all of the above

Last Answer : Answer: A

As shown in the illustration, part 'X' of the diagram is known as a/an _____________. EL-0052 A. commutator B. interpole C. starting pole D. auxiliary pole

Description : As shown in the illustration, part 'X' of the diagram is known as a/an _____________. EL-0052 A. commutator B. interpole C. starting pole D. auxiliary pole

Last Answer : Answer: B

The most practical method used for resurfacing a ship's service motor commutator is to _____________. A. turn it down in the ship's lathe B. use a grinding rig C. use a hand stone D. burnish it with commutator stones

Description : The most practical method used for resurfacing a ship's service motor commutator is to _____________. A. turn it down in the ship's lathe B. use a grinding rig C. use a hand stone D. burnish it with commutator stones

Last Answer : Answer: B

If only one brush on a commutator is sparking excessively, you should look for _____________. A. a high commutator bar B. copper imbedded in the brush C. a loose commutator bar D. flux in the commutating zone

Description : If only one brush on a commutator is sparking excessively, you should look for _____________. A. a high commutator bar B. copper imbedded in the brush C. a loose commutator bar D. flux in the commutating zone

Last Answer : Answer: B

Uneven wear of the commutator surface on a direct current propulsion motor can be caused by _____________. A. rapid change in load B. excessive operation at light load C. incorrect brush staggering D. unequal pole spacing

Description : Uneven wear of the commutator surface on a direct current propulsion motor can be caused by _____________. A. rapid change in load B. excessive operation at light load C. incorrect brush staggering D. unequal pole spacing

Last Answer : Answer: C

Brushes in a generator must be positioned in the neutral plane to avoid sparking between the brushes and the _____________. A. yoke B. armature windings C. field pole windings D. commutator

Description : Brushes in a generator must be positioned in the neutral plane to avoid sparking between the brushes and the _____________. A. yoke B. armature windings C. field pole windings D. commutator

Last Answer : Answer: D

The most effective method of locating a loose commutator bar in a D.C. motor is by _____________. A. visual inspection B. jiggling each by hand C. sounding each bar with a light weight hammer D. checking with a calibrated torque wrench

Description : The most effective method of locating a loose commutator bar in a D.C. motor is by _____________. A. visual inspection B. jiggling each by hand C. sounding each bar with a light weight hammer D. checking with a calibrated torque wrench

Last Answer : Answer: C

The purpose of the commutator and brushes on a DC generator is to _____________. A. transfer generated direct current voltage from the armature to the line B. convert the alternating voltage generated within the armature to a direct voltage C. provide a sliding contact method to excite the field D. reduce sparking between the armature and the carbon brushes

Description : The purpose of the commutator and brushes on a DC generator is to _____________. A. transfer generated direct current voltage from the armature to the line B. convert the alternating voltage ... contact method to excite the field D. reduce sparking between the armature and the carbon brushes

Last Answer : Answer: B

In an AC generator, direct current from a separate source is passed through the windings of the rotor _____________. A. by means of slip rings and brushes B. by means of a commutator C. by means of rotating bar magnet D. to minimize the danger of arc over

Description : In an AC generator, direct current from a separate source is passed through the windings of the rotor _____________. A. by means of slip rings and brushes B. by means of a commutator C. by means of rotating bar magnet D. to minimize the danger of arc over

Last Answer : Answer: A

The electrical diagram shown in the illustration shows _____________. EL-0021 A. 'R1', 'R2', and 'R3' are connected is series B. 'R1', 'R2', and 'R3' are connected in parallel C. the voltages measured across 'R1', 'R2' and 'R3' will be different if 'R1', 'R2' and 'R3' have different values D. the total resistance equals R1 + R2 + R3

Description : The electrical diagram shown in the illustration shows _____________. EL-0021 A. 'R1', 'R2', and 'R3' are connected is series B. 'R1', 'R2', and 'R3' are connected in parallel C. the voltages measured across ... if 'R1', 'R2' and 'R3' have different values D. the total resistance equals R1 + R2 + R3

Last Answer : Answer: B

A back-and-forth pattern of motion that transfers energy A. Wave B. Pulse C. Reflection D. Frequency

Description : A back-and-forth pattern of motion that transfers energy A. Wave B. Pulse C. Reflection D. Frequency

Last Answer : D. Frequency

Which of the following statements best describes the material known as varnished cambric? A. Felted asbestos sealed with varnish. B. Cotton cloth coated with insulating varnish. C. Rubber insulation coated with a layer of tin. D. Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.

Description : Which of the following statements best describes the material known as varnished cambric? A. Felted asbestos sealed with varnish. B. Cotton cloth coated with insulating varnish. C. Rubber ... Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.

Last Answer : Answer: B

The function of the commutator in a DC motor is to ________. A. reverse the flow of current through the armature B. reverse the flow of current in the field poles C. reduce the reluctance of the magnetic path through the motor D. shift the neutral running plane of the brushes to prevent sparking

Description : The function of the commutator in a DC motor is to ________. A. reverse the flow of current through the armature B. reverse the flow of current in the field poles C. reduce the reluctance of the magnetic path through the motor D. shift the neutral running plane of the brushes to prevent sparking

Last Answer : Answer: A

At what frequency compared to the cutoff frequency of a waveguide will the wavefronts be reflected back and forth across the guide (setting up standing waves) and no energy

Description : At what frequency compared to the cutoff frequency of a waveguide will the wavefronts be reflected back and forth across the guide (setting up standing waves) and no energy

Last Answer : UHF receiving antenna

Which of the following methods should be used to dress the face of silver-plated contacts? A. Filing B. Burnishing C. Sanding with 0000 sandpaper D. All of the above are correct.

Description : Which of the following methods should be used to dress the face of silver-plated contacts? A. Filing B. Burnishing C. Sanding with 0000 sandpaper D. All of the above are correct.

Last Answer : Answer: C

Routine maintenance of a ship's service alternator should include ______________. A. changing the pedestal bearing insulation yearly B. megger testing of all rectifying diodes C. lubricating excitation slip rings D. periodic cleaning of the air filters or screens

Description : Routine maintenance of a ship's service alternator should include ______________. A. changing the pedestal bearing insulation yearly B. megger testing of all rectifying diodes C. lubricating excitation slip rings D. periodic cleaning of the air filters or screens

Last Answer : Answer: D

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

Due to which of the following factors the brush wear rate is altered ? (a) Speed of the machine (b) Contact pressure (c) Surface conditions of brush and commutator (d) Excessive sparking (e) All of the above

Description : Due to which of the following factors the brush wear rate is altered ? (a) Speed of the machine (b) Contact pressure (c) Surface conditions of brush and commutator (d) Excessive sparking (e) All of the above

Last Answer : Ans: E

Voltage generated by most AC generators is fed from the machine to the bus by means of ____________. A. brushes on a commutator B. brushes on slip rings C. slip rings on a commutator D. direct connections from the stator

Description : Voltage generated by most AC generators is fed from the machine to the bus by means of ____________. A. brushes on a commutator B. brushes on slip rings C. slip rings on a commutator D. direct connections from the stator

Last Answer : Answer: D

A commutator in a d.c. machine (A) Reduces power loss in armature. (B) Reduces power loss in field circuit. (C) Converts the induced a.c armature voltage into direct voltage. (D) Is not necessary.

Description : A commutator in a d.c. machine (A) Reduces power loss in armature. (B) Reduces power loss in field circuit. (C) Converts the induced a.c armature voltage into direct voltage. (D) Is not necessary.

Last Answer : Ans: C As name suggests, it commutes ac into dc.

You are attempting to parallel two AC generators, and the synchroscope pointer is revolving fast in the clockwise direction. This indicates that the frequency of the incoming machine is _____________. A. higher than the bus frequency B. lower than the bus frequency C. the same as the bus frequency and the circuit breaker may be closed at any pointer position D. the same as the bus frequency but out of phase with it

Description : You are attempting to parallel two AC generators, and the synchroscope pointer is revolving fast in the clockwise direction. This indicates that the frequency of the incoming machine is _____________. A. higher ... at any pointer position D. the same as the bus frequency but out of phase with it

Last Answer : Answer: A

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