Description : Two contributors of electronic console failures are heat and vibration. To combat some of their effects, preventive maintenance procedures should include ______________. A. systematic rotation of circuit cards with those ... bolts and changing of the air in the control room D. all of the above
Last Answer : Answer: B
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
Description : Complete controller maintenance includes _____________. A. periodic testing of protective devices B. checking for loose or worn contacts and weak springs C. maintaining a sufficient supply of spare parts D. all of the above
Last Answer : Answer: D
Description : An advantage of DC motors over AC motors is that they _____________. A. are less expensive B. require less maintenance C. offer infinite speed variation D. all of the above
Last Answer : Answer: C
Description : An advantage of DC motors over AC motors is that they _____________. A. are less expensive B. require less maintenance C. can be started across the line D. offer a more effective means of controlling speed
Description : Which of the following electric motors would be the safest and most reliable to use on the main deck of a vessel in foul weather conditions? A. Sealed motors B. Drip proof motors C. Enclosed motors D. Watertight motors
Description : Two AC generators of the same capacity are operating in parallel. One with a zero speed droop setting and the other with a 5% speed droop. If its capacity is not exceeded, the unit whose ... B. maintain the frequency of the system C. have poor sensitivity characteristics D. have poor power response
Description : A testing device called a 'growler' is being used to locate a shorted coil in the stator of an AC electrical machine. When the 'feeler' is moved over a slot containing the shorted coil _____________. ... . the meter needle will be deflected to zero D. the meter needle will be deflected to full-scale
Description : Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in ... . governor speed droop setting B. voltage regulator C. balance coil D. phase-balance relay
Description : The graph shown in the illustration represents the speed droop curves of two equal capacity alternators about to be paralleled. When paralleled, the greater portion of the total load above 60% for each unit will be picked up ... unit 'A' B. by unit 'B' C. equally by each unit D. none of the above
Description : The governor control switch of an alternator is moved to the 'raise' position. This action will _____________. A. raise the no-load speed setting of the governor B. raise the percentage of speed droop C. lower the no-load speed setting of the governor D. lower the percentage of speed droop
Description : All electric cables passing through watertight bulkheads must be _____________. A. installed with watertight stuffing tubes B. grounded on both sides of the bulkhead C. fitted with unions on each side of the bulkhead D. welded on both sides of the bulkhead
Description : Electrical machinery insulation will break down more rapidly due to _________________. A. low loading of motors and generators B. frequent megger testing C. high temperatures and vibration D. high operating frequencies
Description : The operator of electrical motors should keep a constant check on the loads they carry because _____________. A. low loads necessitate frequent insulation cleaning B. exceeding nameplate values shortens ... wasted if full loading is not utilized D. power factor correction methods are load dependent
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.
Description : When electrical cables penetrate watertight bulkheads, _______________. A. they should be grounded on either side of the bulkhead B. they must be bent to a radius of six diameters C. a watertight stuffing tube capable of accepting packing should be employed D. they should be secured by a clamp
Description : The heating of conductors as a result of resistance in a distribution circuit causes a power loss expressed as _____________. A. line droop B. line loss C. IR drop D. hysteresis
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
Description : Grounds occurring in electrical machinery as a result of insulation failure may result from _____________. A. deterioration through extended use B. excessive heat C. extended periods of vibration D. all of the above
Description : Routine maintenance of dry-type transformers should include ______________. A. preventing the entrance of water from broken pipe lines steam lines B. keeping protective surfaces and insulating bushings free of ... debris C. periodic testing of insulation resistance with a megger D. all of the above
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
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
Description : Electrical failures in motors are caused by the breakdown of insulation, which may be caused by _____________. A. penetration of moisture B. accumulation of dirt C. overheating D. all of the above
Description : The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the _____________. A. loss of residual magnetism B. absorption of moisture in the insulation C. insulation varnish flaking D. dirt collecting on the windings
Description : Routine maintenance of lead acid batteries should include _____________. A. keeping the terminals clean B. coating cable connections with petroleum jelly C. maintaining a trickle charge D. all of the above
Description : When maintenance personnel are working on electrical equipment, all supply switches should be secured in the open position and tagged specifically by the _____________. A. watch engineer B. chief engineer or first assistant C. chief electrician D. person performing the repair
Description : A loss of field excitation to an AC generator while operating in parallel will cause it to ____________. A. absorb more and more load due to decreased armature reaction B. lose its load due to ... polarity D. lose its load, begin to motorize, trip out on reverse power relay, and possibly overspeed
Description : Which of the following is/are true concerning electric power operated watertight door systems? A. Each motor driven door must use the main bus as its source of power. B. Each distribution panel for ... to permit quick activation of the system. D. Each system must have a separate branch circuit.
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 : Biological functions of lipids include (A) Source of energy (B) Insulating material (C) Maintenance of cellular integrity (D) All of these
Last Answer : Answer : D
Description : The function of the autotransformers used with the starters of large AC motors is to provide _____________. A. increased voltage for starting B. increased torque for starting C. reduced voltage for starting D. speed control
Description : What are the limits of vibration measurement for motors?
Last Answer : 50 microns for displacement and 5 mm/second for velocity.
Description : The energy consumed by an AC motor, as strictly reactive power, is _____________. A. used to do mechanical work B. used to establish the magnetic field of the motor C. lost as heat generated by the windings D. lost in doing work to turn the motor itself
Description : The reactive power drawn by a motor from an AC generator is the power which is _____________. A. used to establish the magnetic field of the motor B. lost in overcoming friction in the ... by current flow through the windings D. transmitted directly through the rotor shaft to perform useful work
Description : The apparent power in a purely inductive circuit is also known as _____________. A. true power B. lead power C. induced power D. reactive power
Description : The air gap provided in induction motors should be checked periodically with a feeler gage to detect an unequal air gap and _____________. A. decreased motor magnetizing current B. hysteresis loses C. increased power factor D. mechanical damage to the rotor
Description : The load sharing characteristics of two diesel alternators operating in parallel are directly related to the setting of their governors' ____________. A. load limit B. idle speed C. speed limit D. speed droop
Description : Which of the following statements is true concerning the operation of two alternators in parallel? A. The cycles per second of each alternator are the same. B. Both alternator governors must be set ... be the same on each alternator. D. The load must always be divided equally between alternators.
Description : A turbogenerator has a rated output of 1200 KW at 60 Hertz, with a no load frequency of 61.5 Hertz. What is its speed droop? A. 1.03% B. 1.50% C. 2.44% D. 2.50%
Description : If the driving torque, such as that produced by a diesel engine, creates pulsations when coupled with a synchronous generator operating in parallel; the generator rotor may be periodically pulled ... windings B. direct coupling C. increase governor speed droop D. decreasing governor speed droop
Description : The standard method of controlling the output voltage of a 440 volt, 60 Hz, AC generator is accomplished by adjusting the ____________. A. prime mover speed droop B. number of poles C. alternator field excitation D. load on the alternator
Description : Which of the following will happen to the alternator frequency if the load is removed from a turbogenerator, whose governor has a 3% speed droop? A. It will remain unchanged. B. It will decrease by approximately 3%. C. It will become variable. D. It will increase.
Description : The load sharing characteristics of two diesel generators operating in parallel are mostly dependent on their governor ____________. A. load limit settings B. idle speed settings C. speed limit settings D. speed droop settings
Description : What are the checks on the motor during the preventive maintenance?
Last Answer : IR Value Resistance and Inductance measurement PI value (should > 1.0)
Description : What maintenance checks you will do for an MCC cells and MCC panel?
Last Answer : Maintenance checks on MCC cells a. Ensure that the load is tripped from control room and switch is in off position. Switch off the isolator at MCC cell. b. Open the door and rack ... See for proper earthing connection and tightness of the earthing connections. l. See for proper house keeping.
Description : When disassembling electric motors for maintenance or overhaul, ________________. A. punch mark frame and end bells for proper assembly B. wrap bearings in lint free cloths if they are to be reused C. tag and store small parts in a box D. all of the above
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
Description : The device labeled 'REG SW' in the illustration is used to ___________. EL-0003 A. shift from the automatic voltage regulator to the manual voltage regulator B. shift the governor control from manual to ... device 'REG ADJ' or device 'MAN ADJ' D. supply regulated control power to the switchboard
Description : Severe vibration, accompanied by flashover at the collector rings of an alternator operating in parallel, is a symptom of _____________. A. reverse current motorization B. loss of synchronism C. destructive overspeeding D. reversed polarity
Description : Discoloration of the rotor bars in a squirrel-cage motor is typical evidence of _____________. A. moisture B. overheating C. vibration D. all of the above