Description : The insulation of electric generators during short idle periods should be _____________. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual ... using strip or space heaters D. relieved of all capacitive charge by grounding the conductors
Last Answer : Answer: C
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
Last Answer : Answer: D
Description : Moisture absorbed in the windings or condensed on the surface of electrical machinery insulation ________. A. is good for long term preserving since most insulation is organic and contains some amount B. ... D. reduces the amount of current supplied or drawn by the machine so horsepower is limited
Last Answer : Answer: B
Description : Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. This heat can be developed by ____________. ... an electric welder and feeding it into the armature while running the motor at full speed
Last Answer : Answer: A
Description : A megger is being used to test the insulation of an AC generator. The resistance value of a dry, clean winding will _____________. A. continue to rise as test potential is maintained, ... , becoming fairly steady after 5-7 minutes D. stabilize after approximately 2-4 minutes of fluctuation
Description : When a megohmmeter is used to test insulation, the gradual rise of the pointer reading as a result of continued cranking, is caused by _____________. A. good conductor resistance B. the ... insulation C. the inductive reactance of the windings D. the dielectric-absorption effect of the insulation
Description : In preparing to take insulation resistance readings on a main generator, the windings should be grounded for about 15 minutes prior to the test to _____________. A. allow accurate zeroing of the meter ... the windings D. help the windings to cool to the same temperature as the ground test connection
Description : The removal of paint from electrical equipment, such as generators, should be cautiously undertaken because ____________. A. the mechanical shock of paint removal lessens the dielectric strength ... phase windings frequently become isolated from each other due to dust interference at the terminals
Description : Air gap readings should be taken periodicly on electrical generation equipment to __________. A. determine the amount of varnish that can be applied to correct insulation problems B. determine the ... field coil bolts and correct lateral adjustment of the field coils D. increase machine efficiency
Description : If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of ... the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents
Description : Unnecessary and frequent applications of varnish to the generator windings to repair defective insulation will result in ____________. A. heavy coatings of varnish interfering with heat dissipation B. ... of the rectifier assembly D. a built-up of varnish without changing generator operation
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.
Description : When a megohmmeter is used to test the insulation of a large motor, the initial dip of the pointer toward 'zero' is caused by ____________. A. good insulation B. the capacitance of the ... of the current along the surface of dirty insulation D. the dielectric-absorption effect of the insulation
Description : When using a megohmmeter to test the dielectric strength of wire insulation, a continuous series of slight downscale kicks by the pointer is result of ____________. A. good insulation B. the ... dirty insulation C. the capacitance of the windings D. the dielectric-absorption effect of the insulation
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 : 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 : 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 : In replacing a defective transformer with a new one, which of the following actions must be carried out to insure proper operation of the equipment it serves? A. The secondary leads must be grounded ... magnetize it. D. The iron core must be grounded for 10 minutes to remove any residual magnetism.
Description : Electrical leads and insulation on a motor should be painted with ____________. A. heat-resisting acrylic B. heat-resisting aluminum C. insulating varnish D. insulating white lead
Description : Before testing insulation with a megohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to the test as the ______________. A. insulation may be damaged ... number of leakage paths D. larger machines may acquire a charge of static electricity during operation
Description : Before testing insulation with a megohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to the test, because the ___________. A. static charge of the machine ... number of leakage paths C. insulation may be damaged D. insulation may be covered with moisture
Description : Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator ... rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field
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
Description : Before working on an electric cargo winch master switch or controller, you should _____________. A. spray the gasket surface with a solvent B. drain condensate from the box C. open the circuit breaker in the power supply and tag D. heat the switch box to remove any moisture
Description : When a megohmmeter is used to test the dielectric strength of wire insulation, the initial dip of the pointer toward 'zero' is caused by _____________. A. good insulation B. the leakage of ... of dirty insulation C. the capacitance of the circuit D. the dielectric absorption effect of the insulation
Description : One item listed on the name plate of a cargo pump motor is 'degrees centigrade rise.' This number is based on _____________. A. normal temperature change from cold to hot B. an ambient temperature ... . minimum heat rise from no load to full load D. maximum degrees centigrade rise from absolute zero
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
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
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 : Universal motors will operate on AC or DC current, and are generally found in _____________. A. portable tools B. large pump motors C. turbo electric main motors D. forced draft fans
Description : Voltage build up in an isolated induction generator depends on A. Capacitor bank value B. Residual magnetism of the rotor iron C. Residual magnetism of the stator iron a) A, B b) A, B, C c) B d) A, C
Last Answer : Ans: A
Description : Which of the methods listed is used to start a AC generator turning? A. Residual magnetism remaining in the field poles. B. Residual magnetism remaining in the field coils. C. Residual magnetism remaining in the armature. D. Rotation by a mechanical prime mover.
Description : If a magnetic controller contact fails to pick up when the operating coil is energized, one possible cause may be _______________. A. low spring pressure B. low voltage to the coil C. the residual magnetism of the contact faces D. dirty contact faces
Description : In an alternating current electrical system, a low system power factor is a direct sign of _____________. A. wasted energy B. efficient operation C. a short in the exciter field windings D. an excessive number of minor system grounds
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
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.
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 : Complete maintenance of electrical motors should include periodic checks for machine _____________. A. vibration B. watertight integrity C. speed droop D. reactive power
Description : The greatest single cause of electrical failures is ______. A. the breakdown of insulation B. overcurrent C. high inductance D. too frequent testing
Description : Electrical insulation is classed by the _____________. A. International Association of Electrical Manufacturers B. approximate operating voltage and current expected C. U.S. Coast Guard D. temperature stability of the manufacturing material(s)
Description : Cleaning of electrical insulation should be _____________. A. done every six months B. accomplished every 12 months C. determined by need and not the calendar D. performed whenever the electrician is not otherwise busy
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 : On some electrical generating equipment one outboard bearing pedestal is insulated from the bedplate. To check this insulation with the machine assembled you should use a____________. A. millivolt meter and a jumper B. ohmmeter C. megohm meter D. high potential tester
Description : On some electrical generating equipment one outboard bearing pedestal is insulated from the bedplate. To check this insulation with the machine assembled you should use a____________. A. ohmmeter with the ... C. megohm meter with the machine running D. voltmeter and ampmeter with the machine running
Description : When working on electrical circuits containing large capacitors, in addition to deenergizing the circuit, which of the listed precautions should also be taken? A. Keep all radio equipment ... capacitor insulation resistance. C. Ground the capacitor terminals. D. Check capacitor circuit polarity.
Description : An insulation resistance test is performed on a particular piece of electric equipment. In addition to the resistance reading, what information listed below should be entered in the electrical log? A. ... D. The complete nameplate data from the resistance test instrument used to obtain the reading.
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.
Description : Some large A.C. motors are equipped with with heaters. These could be ___________. I. resistance heaters bolted directly to the frame II. low voltage windings embedded in the motor windings A. I only B. II only C. either I or II D. neither I or II
Description : Moisture damage, as a result of condensation occurring inside of the cargo winch master switches, can be reduced by __________________. A. installing a light bulb in the pedestal stand B. coating the ... epoxy sealer C. venting the switch box regularly D. using strip heaters inside the switch box
Description : What are some examples of electrical equipment which use magnetism?
Last Answer : Motors, generators, speakers, computers, televisions, tape recorders, and many others