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.
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
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
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
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
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
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
Description : If a D.C. motor hums, but does not run when energized, which of the listed conditions could exist? A. Incorrect lead connections B. Incorrect brush setting C. A dirty commutator D. All of the above are correct.
Description : The armature cores of the D.C. motors are constructed with laminations to ___________. A. eliminate hysteresis B. minimize brush sparking C. reduce eddy current losses D. compensate for armature reaction
Description : Brush sparking during commutation may be caused by ________. A. eddy currents in the armature core B. laminations in the generator field pieces C. induced current opposite to coil inductance D. coil inductance discharge occurring at commutation
Description : A three-phase, squirrel cage, induction motor will run hot due to a/an ______________. A. improper brush position B. reversed commutating pole C. shorted stator D. high power factor
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
Description : One of the generator bearing shells is generally insulated from the end housing in order to prevent _____________. A. rapid brush wear B. residual magnetism leak off C. excessive field winding heat D. circulation of shaft currents
Description : One of the generator or motor bearings is generally insulated from the end housing in order to prevent ________. A. rapid brush wear B. current leakage from the shaft C. excessive field winding heat D. circulation of shaft currents induced in the machine's frame
Description : D.C. motor brush adjustment includes attention to _________. A. angle with the commutator and clearance within the holder B. brush length and pigtail tightness C. grade of material and surface dirt conditions D. all of the above
Description : Propulsion DC motor brush pressures can be calculated by _____________. A. dividing the brush contact area by the spring pressure B. subtracting the brush contact area from the spring pressure C. ... force by the brush contact area D. subtracting the spring pressure from the brush contact area
Description : In general, D.C. propulsion motor brush sparking can be caused by _______________. A. incorrect brush grade, pressure or position B. a concentric commutator C. a dark chocolate colored commutator D. all of the above
Last Answer : Answer: A
Description : The direction of rotation of a DC propulsion motor can be changed by reversing the _____________. A. brush holder position B. polarity of the field poles C. brush staggered order D. motor interpole connections
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
Description : A commutator's protective oxide film can be destroyed by _________________. A. periods of low humidity B. very low brush current density C. improper brush grade D. all of the above
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.
Description : An important factor in reducing D.C. motor commutator wear is _______________. A. keeping the ambient humidity as low as possible B. ensuring a very low brush current density C. establishing the copper oxide surface film D. all of the above
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
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
Description : For more complete vessel protection when using an impressed current cathodic system _____________. A. all ship's service alternators have additional temperature sensing devices and a thermal recorder ... with the hull and the propeller shaft is grounded through a slip ring/brush arrangement
Description : The item referred to as a pigtail on a DC motor brush rigging is a/an ______________. A. feather spring B. uninsulated wire C. flexible spring adjuster D. brush holder
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.
Description : The insulation resistance of electric equipment and machinery should be tested for the lowest normal insulation values _____________. A. immediately after shutting down the machine B. every time the brush rigging is ... starting up the machine D. every 30 days whether the machine is in use or not
Description : Which of the following precautions should you take when securing propulsion generators and motors for an extended period of time? A. Disconnect the brush pigtails from their contacts and circulate air ... Lift the brushes from commutator collector rings and circulate cool dry air through the units.
Description : On some diesel-electric ships, the DC propulsion motor will only attain half speed when the generator fields are fully excited. Speeds above this are obtained by _____________. A. rotating brush ... B. raising the generator engine speed C. lowering the generator engine speed D. decreasing excitation
Description : What is the brush pressure on Slipring?
Last Answer : Recommended brush pressure in the Slipring is 150 to 200 gms/cm2 (0.9 to 1 kg).
Description : Why shaft-earthing brush is different from normal brush?
Last Answer : The contact resistance should be very low for shaft earthing brush, to prevent even small current through the oil film, so used copper magnite brush or silver carbon brush.
Description : In accordance with Coast Guard Regulations (46 CFR), a steering gear feeder circuit from the emergency switchboard or alternate power supply must have the capacity for continuous operation of the rudder 15° side to side in not more than 60 seconds for a A. 1/4 hour B. 1/2 hour C. 1 hour D. 2 hours
Description : Coast Guard Regulations (46 CFR), require that an indicating light at the propulsion control station will operate if overloading or overheating occurs in a _______________. A. forced draft blower motor B. steering gear motor C. fuel pump motor D. condensate pump motor
Description : Coast Guard Regulations (46 CFR) require that lighting fixture globes must be protected by guards if the fixtures are located in the ____________. A. steering gear room B. galley C. living quarters D. wheelhouse
Description : According to Coast Guard Regulations (46 CFR), which of the following systems must be arranged so as to be energized by the final emergency power source? A. at least one light in the ... operated watertight door system C. each charging panel for temporary emergency batteries D. all of the above
Description : As shown in the illustrations, ordered rudder angle is fed back from the ________________. EL-0097 A. power unit to the magnetic amplifier B. steering gear to the control potentiometer C. magnetic amplifier to the steering gear D. rudder yoke to the non-followup controller
Description : When power is restored after a complete power failure, a steering gear pump motor will ____________. A. have to be restarted B. have to be reset C. restart automatically D. trip its overload relays
Description : An open-circuit fault between the pressure switch and the 'annunciator module' shown in the illustration would cause the alarm circuit to react in the same manner as if ___________. EL-0094 A. 3.5 ... below switch setting C. 50 PSI were applied to the 'setpoint module' D. the pressure switch closed
Description : If the steering stand selector switch is allowed to remain in the 'Non-Followup' mode after testing of the steering gear, the rudder will _____________. EL-0097 A. not respond to commands from the ... actuator D. stop moving only when the helm is counter-rotated to put the pump at neutral stroke
Description : What are the interlocks between 415 V and 6.6 kV switch gear?
Last Answer : 6.6 kV Breaker closed cannot rack in or out. Service lever cannot move while breaker closed. Breaker cannot be closed in in-between position. 415 V Breaker door cannot be opened when breaker is ... . Breaker cannot be closed in in-between position. Breaker closed cannot be rack in or out.
Description : What is requirement of speeder gear assembly?
Last Answer : To bring the turbine to synchronous speed and get tight lock with grid by grid frequency. BPC signal is given in Auto mode to the speeder gear motor.
Description : What are the logic’s adopted in barring gear motor?
Last Answer : For start permission a) Local or remote start. b) JOP is running. c) Motor hand barring is permissive. d) 42 contactor in MCC is off. e) Turbine speed is <100 rpm. Start permission (42S ... is >0.35 kg/ cm2. e) No thermal over load of 42. f) No one-DG condition.
Description : What are the purposes of barring gear?
Last Answer : Start rotor from rest. Eliminates sag in rotor - straighten and avoid rubbing at glands. Avoid direct contact journals and bearings. Avoid differential temp between top and bottom of cylinder due to convection of Steam or hot air inside turbine cylinders.
Description : Why starting resistor is provided in barring gear motor?
Last Answer : Starting resistance at stator reduces voltage at stator terminals and accelerates the motor very slowly so as to allow smooth gear engagement. Other methods are a) Auto transformer. b) Star-delta starter.
Description : What is the function of speeder gear?
Last Answer : Speed raising beyond governor takeover speed upto full speed is achieved by raising and lowering the speeder gear.
Description : What are the purposes of turning gear?
Last Answer : Turning gear is used to run the turbine from rest to low speed and from normal running speed to low speed with the help of barring motor to eliminate the hogging and sagging of turbine because of the high temperature.
Description : What type brush plants live on Hawaii mountains?
Last Answer : Need answer
Description : The metering mechanism used in potato planter is: A. Fluted roller B. Brush feed type C. Picker wheel type D. Cell feed type
Last Answer : Picker wheel type