Which of the following statements is true concerning the cleaning of electrical contacts? A. Compressed air should be used to blow out metallic dust. B. Magnetic brushes should be used to remove metallic dust. C. The contact surfaces should be greased to increase contact resistance. D. Delicate parts should be cleaned with a brush and an approved safety solvent.

Which of the following statements is true concerning the cleaning of electrical contacts? A. Compressed air should be used to blow out metallic dust. B. Magnetic brushes should be used to remove metallic dust. C. The contact surfaces should be greased to increase contact resistance. D. Delicate parts should be cleaned with a brush and an approved safety solvent.
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Answer: D
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Related questions

Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an _______________. A. small wire brush B. compressed air jet C. clean dry cloth D. 10% solution carbon solvent and water

Description : Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an _______________. A. small wire brush B. compressed air jet C. clean dry cloth D. 10% solution carbon solvent and water

Last Answer : Answer: C

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

Which of the following statements, concerning the general maintenance of a brushless generator, is correct? A. Paint should be applied to insulating surfaces on an annual basis. B. Alcohol should be used to remove dust and grime from windings. C. High pressure air should be used to blow out carbon dust. D. Accessible generator parts should be wiped with a clean dry rag on a periodic basis.

Description : Which of the following statements, concerning the general maintenance of a brushless generator, is correct? A. Paint should be applied to insulating surfaces on an annual basis. B. Alcohol should be used to ... . D. Accessible generator parts should be wiped with a clean dry rag on a periodic basis.

Last Answer : Answer: D

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 following procedures should be used to maintain a large electric motor during periods of inactivity? A. A thin layer of air-drying varnish should be applied on the windings. B. Compressed air should be blown over areas where dust is deposited. C. Spraying a solvent periodically to remove carbon dust. D. Space heaters should be used to prevent condensation of moisture.

Description : Which of the following procedures should be used to maintain a large electric motor during periods of inactivity? A. A thin layer of air-drying varnish should be applied on the windings. B. ... periodically to remove carbon dust. D. Space heaters should be used to prevent condensation of moisture.

Last Answer : Answer: D

Controller contacts should be routinely cleaned by ________. A. blowing with compressed air B. filing with a bastard file C. wiping with a clean dry cloth D. dressing with crocus cloth

Description : Controller contacts should be routinely cleaned by ________. A. blowing with compressed air B. filing with a bastard file C. wiping with a clean dry cloth D. dressing with crocus cloth

Last Answer : Answer: C

If a small electric motor has been submerged in saltwater for a short period of time, you should _____________. A. send it ashore for rewinding B. rinse it with warm freshwater and bake it dry in an oven C. soak it in a bucket of commercial solvent and bake with internal heat D. clean it with carbon tetrachloride and blow it out with compressed air

Description : If a small electric motor has been submerged in saltwater for a short period of time, you should _____________. A. send it ashore for rewinding B. rinse it with warm freshwater and bake it dry ... and bake with internal heat D. clean it with carbon tetrachloride and blow it out with compressed air

Last Answer : Answer: B

Burning of controller contacts, when opening, is prevented by _____________. A. coating the contact surfaces lightly with petroleum jelly B. magnetic blowout coils C. an overvoltage release D. an overcurrent release

Description : Burning of controller contacts, when opening, is prevented by _____________. A. coating the contact surfaces lightly with petroleum jelly B. magnetic blowout coils C. an overvoltage release D. an overcurrent release

Last Answer : Answer: B

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

Compressed air should not be used to clean motor controller equipment because ________________. A. it may force metallic particles into coil insulation B. the surrounding area may need additional cleaning C. the air blast dries out insulation quickly D. a mask and respirator would be required

Description : Compressed air should not be used to clean motor controller equipment because ________________. A. it may force metallic particles into coil insulation B. the surrounding area may need additional cleaning C. the air blast dries out insulation quickly D. a mask and respirator would be required

Last Answer : Answer: A

When a solid-state component of an electronic circuit is mounted to a metallic mass, the general purpose of that mass is to ____________. A. prevent vibration damage to delicate components B. prevent mechanical damage to solid-state components C. dissipate stray magnetic currents D. act as a heat sink

Description : When a solid-state component of an electronic circuit is mounted to a metallic mass, the general purpose of that mass is to ____________. A. prevent vibration damage to delicate components B. prevent ... damage to solid-state components C. dissipate stray magnetic currents D. act as a heat sink

Last Answer : Answer: D

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

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

Chattering of the collector ring brushes on a generator may be remedied by _____________. A. lubricating brush holders B. reinsulating the brushes C. cleaning the collector rings D. increasing length of pigtail

Description : Chattering of the collector ring brushes on a generator may be remedied by _____________. A. lubricating brush holders B. reinsulating the brushes C. cleaning the collector rings D. increasing length of pigtail

Last Answer : Answer: C

In the illustration, the purpose of part B is to _________. EL-0033 A. increase resistance in series with the contacts as they close to prevent arcing B. create a magnetic field in the steel plates that interacts with the arc to cool and extinguish the arc C. cause the contacts to open in the event of an overload D. provide ventilation to the contact when the breaker is close to rated capacity

Description : In the illustration, the purpose of part B is to _________. EL-0033 A. increase resistance in series with the contacts as they close to prevent arcing B. create a magnetic field in the steel ... event of an overload D. provide ventilation to the contact when the breaker is close to rated capacity

Last Answer : Answer: B

In actual applications, electrical connections to 'R1-R2' of figure 'A' and to 'R1-R2- R3' of figure 'B' shown in the illustration are made by ______________. EL-0092 A. soldered contacts B. spliced and taped connections C. slip rings and brushes D. solderless crimp-on connectors

Description : In actual applications, electrical connections to 'R1-R2' of figure 'A' and to 'R1-R2- R3' of figure 'B' shown in the illustration are made by ______________. EL-0092 A. soldered contacts B. spliced and taped connections C. slip rings and brushes D. solderless crimp-on connectors

Last Answer : Answer: C

Which of the following statements is true concerning all three-phase alternators? A. Each has three separate but identical armature windings acted on by one system of rotating magnets. B. Each has one armature winding acted on by three identical but separate systems of rotating magnets. C. All three-phase alternators are designed to operate with a 0.8 leading power factor. D. The three phases always provide power to the load through three sets of slip rings and brushes.

Description : Which of the following statements is true concerning all three-phase alternators? A. Each has three separate but identical armature windings acted on by one system of rotating magnets. B. Each has one ... The three phases always provide power to the load through three sets of slip rings and brushes.

Last Answer : Answer: A

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

During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points

Description : During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points

Last Answer : Answer: B

Which of the following statements is true concerning the operating characteristics of a squirrel-cage motor? A. Rotor slip is dependent upon the motor load. B. An increase in motor load results in less slip. C. A decrease in rotor speed results in less generated current. D. A decrease in rotor speed produces a weaker magnetic field.

Description : Which of the following statements is true concerning the operating characteristics of a squirrel-cage motor? A. Rotor slip is dependent upon the motor load. B. An increase in motor load results in ... results in less generated current. D. A decrease in rotor speed produces a weaker magnetic field.

Last Answer : Answer: A

Sparking at the brushes of a DC propulsion motor can be the result of ____________. A. improper brush pressure B. improper brush seating C. reversed interpole polarity D. all of the above

Description : Sparking at the brushes of a DC propulsion motor can be the result of ____________. A. improper brush pressure B. improper brush seating C. reversed interpole polarity D. all of the above

Last Answer : Answer: D

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

Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Description : Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Last Answer : Answer: D

When the motor shown in the illustration is running and the stop button is pushed, which of the following statements will hold true? EL-0010 A. Coil 'M' will now be energized. B. Coil 'CR' will now be energized. C. Contact 'M' will close as contact 'CR' opens. D. Contacts 'M' and 'CR' will open.

Description : When the motor shown in the illustration is running and the stop button is pushed, which of the following statements will hold true? EL-0010 A. Coil 'M' will now be energized. B. Coil 'CR' will now be energized. C. Contact 'M' will close as contact 'CR' opens. D. Contacts 'M' and 'CR' will open.

Last Answer : Answer: D

As shown in the illustration, the symbol is used in electrical drawings to designate a ____________. EL-0026 A. limit switch with one set of normally open contacts B. maintaining type push button with an electrical interlock C. sustaining type push button with a mechanical interlock D. normally closed contact held open mechanically by an interlock

Description : As shown in the illustration, the symbol is used in electrical drawings to designate a ____________. EL-0026 A. limit switch with one set of normally open contacts B. maintaining type ... type push button with a mechanical interlock D. normally closed contact held open mechanically by an interlock

Last Answer : Answer: C

Which of the following statements represents the FIRST precaution to be taken prior to working on any installed electrical component? A. Wear rubber gloves and boots. B. Use only approved nonconducting tools. C. Ground the case of the machine before beginning any repairs. D. Open the supply circuits and tag the switches.

Description : Which of the following statements represents the FIRST precaution to be taken prior to working on any installed electrical component? A. Wear rubber gloves and boots. B. Use only approved nonconducting ... the machine before beginning any repairs. D. Open the supply circuits and tag the switches.

Last Answer : Answer: D

A loud buzzing noise at the contacts of a magnetic controller could indicate _____________. A. weak contact spring pressure B. misalignment of the magnet faces C. excessive line current D. mechanical binding

Description : A loud buzzing noise at the contacts of a magnetic controller could indicate _____________. A. weak contact spring pressure B. misalignment of the magnet faces C. excessive line current D. mechanical binding

Last Answer : Answer: B

Magnetic controller contacts may become welded together during operation because of _____________. A. excessive magnetic gap B. low contact pressure C. an open coil D. excessive ambient temperature

Description : Magnetic controller contacts may become welded together during operation because of _____________. A. excessive magnetic gap B. low contact pressure C. an open coil D. excessive ambient temperature

Last Answer : Answer: B

Magnetic controller contacts may become welded together during operation due to _____________. A. an open coil B. low contact pressure C. excessive ambient temperature D. excessive magnetic gap

Description : Magnetic controller contacts may become welded together during operation due to _____________. A. an open coil B. low contact pressure C. excessive ambient temperature D. excessive magnetic gap

Last Answer : Answer: B

The main difference between a motor control circuit containing low voltage protection and low voltage release is that the latter contains _____________. A. a magnetic operating coil B. normally open line contacts C. thermal-overload protection D. a momentary-contact start button

Description : The main difference between a motor control circuit containing low voltage protection and low voltage release is that the latter contains _____________. A. a magnetic operating coil B. normally open line contacts C. thermal-overload protection D. a momentary-contact start button

Last Answer : Answer: D

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

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

The air gap in an induction motor should be checked periodically with a feeler gage to detect ____________. A. rotor contact with the laminations B. changes in armature magnetic strength C. excessive bearing wear D. electrical damage to the rotor

Description : The air gap in an induction motor should be checked periodically with a feeler gage to detect ____________. A. rotor contact with the laminations B. changes in armature magnetic strength C. excessive bearing wear D. electrical damage to the rotor

Last Answer : Answer: C

Which of the following statements is true concerning simple parallel resistance circuits? A. The total current flow equals the sum of the individual currents. B. The total current flow equals the reciprocal of the sum of the individual currents. C. The total resistance equals the sum of the individual resistance. D. The total voltage equals the sum of the individual voltages across each resistance.

Description : Which of the following statements is true concerning simple parallel resistance circuits? A. The total current flow equals the sum of the individual currents. B. The total current flow equals the ... resistance. D. The total voltage equals the sum of the individual voltages across each resistance.

Last Answer : Answer: A

Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. The starting current is held below the rated current. D. The field winding is energized for starting purposes only.

Description : Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. ... is held below the rated current. D. The field winding is energized for starting purposes only.

Last Answer : Answer: A

Electrical contact materials used in switches, brushes and relays must possess

Description : Electrical contact materials used in switches, brushes and relays must possess   (A) high thermal conductivity and high melting point  (B) Low thermal conductivity and low melting point   (C) High thermal conductivity and low melting point  (D) Low thermal conductivity and high melting point.

Last Answer : Electrical contact materials used in switches, brushes and relays must possess high thermal conductivity and high melting point 

If deck machinery is expected to be idle for an extended period of time you should____________. A. have electrical safety gloves available in case of electrical shock before running B. perform a 'high pot' test to determine the condition of the insulation C. water wash the motor and controller to remove any salt that may interfere with smooth operation D. check run at regular intervals to inusre correct operation and to renew the internal coating of lubrication

Description : If deck machinery is expected to be idle for an extended period of time you should____________. A. have electrical safety gloves available in case of electrical shock before running B. perform ... run at regular intervals to inusre correct operation and to renew the internal coating of lubrication

Last Answer : Answer: D

Which of the following statements concerning electrical cables is correct? A. Where they pass through watertight bulkheads, they should be fitted with watertight stuffing boxes. B. Electric cable coverings should never be grounded. C. Electrical cables must be rigidly held in place by welding of armored cable, or glued in place where nonmetallic insulation is used. D. All of the above.

Description : Which of the following statements concerning electrical cables is correct? A. Where they pass through watertight bulkheads, they should be fitted with watertight stuffing boxes. B. Electric cable coverings should ... , or glued in place where nonmetallic insulation is used. D. All of the above.

Last Answer : Answer: A

Which surfaces should be cleaned with a pressure washer?

Description : Which surfaces should be cleaned with a pressure washer?

Last Answer : Powerwashers should only be used on hard surfaces. You should use power washers on materials like concrete, tar, stone, and other materials that are strong.

How much rail ends are cleaned with Kerosene Oil and steel wire brush? (i) Minimum 100 mm both side (ii) Minimum 50 mm both side.* (iii) No need (iv) As decided by site supervisor

Description : How much rail ends are cleaned with Kerosene Oil and steel wire brush? (i) Minimum 100 mm both side (ii) Minimum 50 mm both side.* (iii) No need (iv) As decided by site supervisor

Last Answer : (ii) Minimum 50 mm both side.*

Etched or burned bands on the contact faces of the brushes in a direct current generator can be caused by ____________. A. high mica segments B. copper drag on the commutator C. brushes improperly positioned D. copper embedded in the brushes

Description : Etched or burned bands on the contact faces of the brushes in a direct current generator can be caused by ____________. A. high mica segments B. copper drag on the commutator C. brushes improperly positioned D. copper embedded in the brushes

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

When primary molars are prepared for stainless steel crowns, should the depth for reduction of the proximal surface be similar to the depth of the buccal and lingual surfaces? A. Yes; reduction of all wall is similar for best retention B. No, proximal reduction is greater to allow the crown to pass the contact area C. No, the buccal surfaces has the greatest reduction to remove the cervical bulge D. Yes, all undercuts are uniformly removed so that the steel crown can be seated E. No, because of lateral constriction, the lingual surface needs greatest reduction

Description : When primary molars are prepared for stainless steel crowns, should the depth for reduction of the proximal surface be similar to the depth of the buccal and lingual surfaces? A. Yes; reduction ... can be seated E. No, because of lateral constriction, the lingual surface needs greatest reduction

Last Answer : B. No, proximal reduction is greater to allow the crown to pass the contact area

Sparking of D.C. motor brushes can be caused by __________. A. an open commutating winding B. many mechanical, electrical or operating faults C. an open interpole D. all of the above

Description : Sparking of D.C. motor brushes can be caused by __________. A. an open commutating winding B. many mechanical, electrical or operating faults C. an open interpole D. all of the above

Last Answer : Answer: B

Which of the following statement(s) is/are true concerning pharmacologic agents used to accelerate wound healing? a. A number of these agents are now currently approved for use in this country b. PDGF (platelet-derived growth factor) promotes fibroblast proliferation, chemotaxis, and collagenase synthesis c. PDGF has been demonstrated in a number of clinical trials to promote healing in chronic wounds d. Growth hormone functions by promoting fibroblast proliferation and collagen synthesis

Description : Which of the following statement(s) is/are true concerning pharmacologic agents used to accelerate wound healing? a. A number of these agents are now currently approved for use in ... healing in chronic wounds d. Growth hormone functions by promoting fibroblast proliferation and collagen synthesis

Last Answer : Answer: b, c Currently there are no approved clinical agents that accelerate normal healing. Although a number of clinical trials are in progress, no agents are currently ... hormone administration significantly accelerates donor site healing, presumably due to its effects in minimizing catabolism

As part of a routine maintenance program for deck machinery, you should ___________. A. inspect electrical wiring and pushbutton switches for evidence of corrosion or burned insulation B. disassemble pushbutton switches and drain water each week C. remove motor covers and ventilate as weather permits D. Check drum switch contact pressure every three months

Description : As part of a routine maintenance program for deck machinery, you should ___________. A. inspect electrical wiring and pushbutton switches for evidence of corrosion or burned insulation B. disassemble ... covers and ventilate as weather permits D. Check drum switch contact pressure every three months

Last Answer : Answer: A