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.

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.
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1 Answer

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Answer: A
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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

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

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

Description : 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

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

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

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

The current from the stator of an alternator is taken out to the external load circuit through (A) slip rings. (B) commutator segments. (C) solid connections. (D) carbon brushes.

Description : The current from the stator of an alternator is taken out to the external load circuit through (A) slip rings. (B) commutator segments. (C) solid connections. (D) carbon brushes.

Last Answer : (C) solid connections.

A generator has been exposed to water and is being checked for its safe operation. Therefore, it is necessary to _______________. A. check for shorted coils with a growler B. take moisture readings with a hydrometer C. test insulation values with a megger D. ground the commutator, or slip rings and run it at half load for 12 hours

Description : A generator has been exposed to water and is being checked for its safe operation. Therefore, it is necessary to _______________. A. check for shorted coils with a growler B. take moisture readings with a ... a megger D. ground the commutator, or slip rings and run it at half load for 12 hours

Last Answer : Answer: C

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

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

The reversal of an AC, three-phase, induction motor is accomplished by ______________. A. changing all three motor leads B. reversing the position of the slip rings C. interchanging any two of the three motor leads D. interchanging any two brushes

Description : The reversal of an AC, three-phase, induction motor is accomplished by ______________. A. changing all three motor leads B. reversing the position of the slip rings C. interchanging any two of the three motor leads D. interchanging any two brushes

Last Answer : Answer: C

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

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

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

In an induction motor, rotor currents are circulated in the rotor by _____________. A. slip rings and brushes B. an armature and brushes C. inductive reaction of the rotating stator field D. external variable resistors

Description : In an induction motor, rotor currents are circulated in the rotor by _____________. A. slip rings and brushes B. an armature and brushes C. inductive reaction of the rotating stator field D. external variable resistors

Last Answer : Answer: C

Brushless generators are designed to operate without the use of ___________. A. brushes B. slip rings C. commutators D. all of the above

Description : Brushless generators are designed to operate without the use of ___________. A. brushes B. slip rings C. commutators D. all of the above

Last Answer : Answer: D

What are the materials used to manufacture the brushes for slip rings of an induction motor?

Description : What are the materials used to manufacture the brushes for slip rings of an induction motor?

Last Answer : A:The slip rings are made of brass and phosphor bronze. The brushes are made of metal graphite which is an alloy of copper and carbon.

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.

Description : 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 ... contact resistance. D. Delicate parts should be cleaned with a brush and an approved safety solvent.

Last Answer : Answer: D

If an AC generator experiences voltage failure, the cause may be _____________. A. an open in the field circuit B. the brushes shifting out of the neutral plane C. excessive locked-rotor current D. a rotating slip ring

Description : If an AC generator experiences voltage failure, the cause may be _____________. A. an open in the field circuit B. the brushes shifting out of the neutral plane C. excessive locked-rotor current D. a rotating slip ring

Last Answer : Answer: A

How cooling is done for slip ring and brush gear?

Description : How cooling is done for slip ring and brush gear? 

Last Answer : A centrifuge fan is mounted on the shaft in between two slip rings for ventilation of the slip rings and brush gear.

Which of the following are the parts of a DC generator that convert the AC in the armature to DC in the external circuit. Are these parts the: w) field poles x) slip rings and the brushes y) commutator and the brushes z) armature and the core

Description : Which of the following are the parts of a DC generator that convert the AC in the armature to DC in the external circuit. Are these parts the: w) field poles x) slip rings and the brushes y) commutator and the brushes z) armature and the core

Last Answer : ANSWER: Y -- COMMUTATOR AND THE BRUSHES

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

State the function of following parts of slip ring induction motor: (i) Slip ring (ii) Fan (iii) Brushes (iv) Frame

Description : State the function of following parts of slip ring induction motor: (i) Slip ring (ii) Fan (iii) Brushes (iv) Frame

Last Answer : Sr. No. Name of part Function 1 Slip ring 1) The rotor winding terminals are permanently connected to the slip rings. 2) Connects external resistance to rotor circuit through ... It provides mechanical support to the entire internal parts of motor. 2) Protects the inner parts.

A three-phase, squirrel cage, induction motor will run hot due to _____________. A. open stator coils B. high power factor C. dirty or corroded slip rings D. reversed commutating poles

Description : A three-phase, squirrel cage, induction motor will run hot due to _____________. A. open stator coils B. high power factor C. dirty or corroded slip rings D. reversed commutating poles

Last Answer : Answer: A

Which of the statements given below is not true about formation of annual rings in trees? (a) Annual rings are not prominent in trees of temperate region. (b) Annual ring is a combination of spring wood and autumn wood produced in a year. (c) Differential activity of cambium causes light and dark bands of tissue-early and late wood respectively. (d) Activity of cambium depends upon variation in climate.

Description : Which of the statements given below is not true about formation of annual rings in trees? (a) Annual rings are not prominent in trees of temperate region. (b) Annual ring is a combination ... of tissue-early and late wood respectively. (d) Activity of cambium depends upon variation in climate.

Last Answer : a) Annual rings are not prominent in trees of temperate region

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

Which of the following statements describes what will occur if the motor shown in the illustration is required to carry 150% of full load? EL-0056 A. The primary counter emf will be increased. B. The stator current will increase. C. The slip will decrease. D. The slip value, stator current curve, and torque curve will all coincide.

Description : Which of the following statements describes what will occur if the motor shown in the illustration is required to carry 150% of full load? EL-0056 A. The primary counter emf will be increased. B. ... slip will decrease. D. The slip value, stator current curve, and torque curve will all coincide.

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

The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open

Description : The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction to the ... frequency of induced voltage across slip ring is A) 30 Hz B) 70 Hz C) 20 Hz D) 35 Hz

Last Answer : The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction to the normal direction, The frequency of induced voltage across slip ring is 70 Hz

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

When an alternator is to remain idle for even a few days _________________. A. lift the brushes and disconnect the pigtails B. insulate the collector rings with strips of cardboard C. energize the heater circuit D. open the equalizing bus disconnect switch

Description : When an alternator is to remain idle for even a few days _________________. A. lift the brushes and disconnect the pigtails B. insulate the collector rings with strips of cardboard C. energize the heater circuit D. open the equalizing bus disconnect switch

Last Answer : Answer: C

Modern DC generators are fitted with commutating poles to _____________. A. prevent motorizing B. reduce sparking C. reduce the load on the main poles D. reduce spring pressure on the brushes

Description : Modern DC generators are fitted with commutating poles to _____________. A. prevent motorizing B. reduce sparking C. reduce the load on the main poles D. reduce spring pressure on the brushes

Last Answer : Answer: B

___arrow represents the value obtained by evaluating right side expression/variable to the left side variable. a. Forth b. Inbetween co. Back d. None of these

Description : ___arrow represents the value obtained by evaluating right side expression/variable to the left side variable. a. Forth b. Inbetween co. Back d. None of these

Last Answer : co. Back

Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while starting. C. The brushes are removed from the commutator while starting. D. They have a low starting torque.

Description : Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while ... brushes are removed from the commutator while starting. D. They have a low starting torque.

Last Answer : Answer: B

The main purpose of an electric space heater installed in a large AC generator is to _____________. A. keep the lube oil warm for quick starting B. prevent moisture from condensing in the windings when the machine is shutdown C. prevent the windings from becoming brittle D. prevent acidic pitting of the slip rings

Description : The main purpose of an electric space heater installed in a large AC generator is to _____________. A. keep the lube oil warm for quick starting B. prevent moisture from condensing in the ... is shutdown C. prevent the windings from becoming brittle D. prevent acidic pitting of the slip rings

Last Answer : Answer: B

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

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

The main purpose of an electric space heater installed in a large AC generator is to _____________. A. prevent the windings from becoming brittle B. prevent moisture from condensing in the windings during shutdown C. prevent acidic pitting of the slip rings D. keep the lube oil warm for quick starting

Description : The main purpose of an electric space heater installed in a large AC generator is to _____________. A. prevent the windings from becoming brittle B. prevent moisture from condensing in the windings during ... C. prevent acidic pitting of the slip rings D. keep the lube oil warm for quick starting

Last Answer : Answer: B

Erratic operation of the devices represented in the diagrams shown in the illustration could be traced to ____________. EL-0092 A. improper contact at 'R' slip rings or 'S' connections B. a low three-phase voltage supply C. improper contact at 'S' slip rings or 'R' connections D. a high three-phase voltage supply

Description : Erratic operation of the devices represented in the diagrams shown in the illustration could be traced to ____________. EL-0092 A. improper contact at 'R' slip rings or 'S' connections B. a low three- ... . improper contact at 'S' slip rings or 'R' connections D. a high three-phase voltage supply

Last Answer : Answer: A

Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel cage motor does not? A. Slip rings B. End rings C. A centrifugal switch D. End plates

Description : Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel cage motor does not? A. Slip rings B. End rings C. A centrifugal switch D. End plates

Last Answer : Answer: A

While starting a main propulsion synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. This indicates the _____________. A. motor has started properly B. field windings are grounded C. slip rings are dirty D. power transmission cables are grounded

Description : While starting a main propulsion synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. This indicates the _____________. A. motor has started ... field windings are grounded C. slip rings are dirty D. power transmission cables are grounded

Last Answer : Answer: A

What are slip rings?

Description : What are slip rings?

Last Answer : The slip rings are made of copper alloys and are fixed around the shaft insulating it. Through these slip rings and brushes the rotor winding can be connected to external circuits.

What are the routines checks on slip rings?

Description : What are the routines checks on slip rings?

Last Answer : a. Correct mV drops brush to be used. b. Brush tension adjustment. c. Air cleaning to reduce leakage current. d. Brush bedding before use. e. Field polarity change every 6 months. 

D.C. propulsion motor brush pressure depends on the brush grade used and in practice is set with a ______________. A. multimeter B. manometer C. spring scale D. compound gauge

Description : D.C. propulsion motor brush pressure depends on the brush grade used and in practice is set with a ______________. A. multimeter B. manometer C. spring scale D. compound gauge

Last Answer : Answer: C

The most practical method of controlling the RPM of a step-speed AC motor is to _____________. A. change input voltage B. vary the number of poles C. vary power factor D. change the number of brushes

Description : The most practical method of controlling the RPM of a step-speed AC motor is to _____________. A. change input voltage B. vary the number of poles C. vary power factor D. change the number of brushes

Last Answer : Answer: B

The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip increases, rotor reactance decreases. B. The pullout point on the torque curve is about seven times the normal full load torque value. C. At stand still, stator current is 150% of normal. D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Description : The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip ... D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Last Answer : Answer: D