Description : One method of testing for a reversed shunt field coil in a DC generator or motor is by connecting the field to a direct current source, at reduced field rated voltage, and test for ... placed near each field C. test lamp across adjacent fields D. copper jumper across the interpole connections
Last Answer : Answer: B
Description : An electrical connection between the wiring of an electric motor and its metal frame is known as a/an _____________. A. eddy current B. ground C. impedance D. flux leakage
Description : An open armature connection in a DC propulsion motor could be caused by ____________. A. low-load operation B. clogged ventilation ducts C. sparking at the brushes D. a grounded shunt field coil
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 : A current carrying conductor making an electrical contact with a wiring metal conduit is indicated by a _____________. A. low switchboard wattmeter reading B. reading of 1.0 on the power factor meter C. high switchboard voltmeter reading D. totally darkened switchboard ground-detecting light
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
Description : A galvanometer is an instrument used to measure ___________. A. thickness of galvanized metal B. resistance of electrical wiring insulation C. very small amounts of current or voltage D. quantity of galvans in an electric circuit
Last Answer : Answer: C
Description : In the construction of D.C. motors, parts of both the series and shunt fields are wound on the _____________. A. opposite main pole B. rotor core C. interpole D. same main pole
Description : The ground indicating light on the main electrical switchboard is indicating a ground. The best procedure for locating the grounded circuit is to _____________. A. trace the circuit paths while looking for ... a time, until the lights no longer indicate a ground D. check all circuits for continuity
Description : As compared to shunt and compound DC motors, the series DC motor will have the highest torque because of its comparatively ____________ at the start. (A) Lower armature resistance. (B) Stronger series field. (C) Fewer series turns. (D) Larger armature current.
Last Answer : (D) Larger armature current.
Description : When an AC or a DC motor fails to start, the FIRST step in troubleshooting should be to check the ____________. A. motor windings for obvious opens B. motor controller leads for continuity C. fuse or circuit breaker D. motor controller leads for grounds
Description : When using a megohmmeter to determine which shunt field coil is grounded in a DC machine, you must ____________. A. insulate the field frame from the ship's hull B. disconnect each shunt ... C. use a motor driven high capacity megohmmeter D. remove all main line lead connections before testing
Description : As shown in the illustration, the motor generator(M-G) set's three-phase motor drives the ______________. EL-0101 A. motor and the generator B. motor and the exciter C. generator and the exciter D. main field and the interpole field
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 : As shown in the illustration, the M-G set's three-phase motor drives the ______________. EL-0101 A. motor and the generator B. motor and the exciter C. generator and the exciter D. main field and the interpole field
Description : A ground in an electrical circuit outside the engine room _____________. A. cannot be detected under normal conditions B. is of no consequence to engineering personnel C. is indicated at the branch circuit breaker panel D. is indicated by the ground detecting lamps on the main switchboard
Description : Which of the listed electrical devices is represented by the symbol shown in the illustration? EL-0055 A. Fixed resistance resistor B. Coil with magnetic core C. DC motor or generator shunt field D. Transformer
Description : As shown in the illustration, the electrical symbol is used to indicate which of the listed types of motors? EL-0054 A. Shunt motor. B. Series motor. C. Compound motor. D. Tri-field motor.
Description : An open shunt field in a direct current machine may be located by connecting the field circuit to an external power source, equal to the rated field voltage or less, and tested with a voltmeter from ... C. any suitable ground to any available line lead D. any field pole to each field coil lead
Last Answer : Answer: A
Description : Which of the illustrations listed below is representative of a motor controller's 'wiring' or 'connection' diagram? Book A. EL-0023 B. EL-0024 C. EL-0037 D. EL-0058
Description : A current-carrying conductor making electrical contact with a wiring conduit will be indicated by a _____________. A. high switchboard wattmeter reading B. totally dark switchboard ground detecting light C. low switchboard wattmeter reading D. all of the above
Description : Accidental grounds in a shipboard electrical system must be repaired as soon as possible as they will ____________. A. result in immediate power outages B. damage circuit breakers C. appear on the ground detection system D. damage insulation and may cause outages
Description : If a single-phase induction motor fails to start, the problem may be _____________. A. an open in the main winding B. a shorted shunt field C. a closed centrifugal switch D. low circuit frequency
Description : If a single-phase induction motor fails to start, the problem may be _____________. A. an open in the run winding B. a shorted shunt field C. a closed centrifugal switch D. low circuit frequency
Description : When the series field relay "FR" of the winch circuit shown in the illustration is energized during dynamic braking the _______________. EL-0102 A. shunt Field Relay "FR-B.O." is de-energized and contacts ... . shunt Field Relay "FR-B.O." opposes the series coil's flux and sets the mechanical brake
Description : If a unloaded shunt motor's field were weakened by rheostat resistance or by an open circuit, the motor would _________. A. overspeed due to reduced CEMF B. stop because of low flux C. continue to run at base speed D. slow down and overheat
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
Description : When reading electrical motor controller diagrams, it helps to know that ____________. A. current paths in the control circuit are drawn as heavy lines and in the power circuit as lighter lines B. current ... subject to 500 volts or greater are drawn as light lines and below 500 volts as heavy lines
Description : Which of the listed conditions could cause a DC motor to have excessively hot windings and sparking at the brushes? A. Reversed interpole polarity B. High bar-to-bar voltage C. Loose brushes D. Excessive humidity
Description : Relative to the direction of rotation, a D.C. motor commutating pole has the same polarity as the _____________. A. main pole following B. interpole following C. main pole preceding D. interpole preceding
Description : When a console indicating lamp burns out, attempts to renew it should not be made while maneuvering because _______________. A. the new lamp may be of a higher wattage and cause heat damage to the lens ... D. a socket/wiring fault may cause a ground or short circuit to shut down a vital function
Description : Voltage failure of an AC generator may be caused by ____________. A. failure of the exciter generator B. a tripped bus circuit breaker C. high mica segments on the stator bus bar D. excessive prime mover speed
Description : As shown in the illustration, 'B' is a ____________. EL-0058 A. single-pole, double-throw switch B. double-pole, single-throw switch C. double-pole, double-throw switch D. circuit breaker
Description : Undervoltage trips are frequently installed on switchboard circuit breakers to trip ____________. A. out generators in the event of severe arcing or sparking B. out generators when there is reversal of power ... , but continues to run D. out generators when there is low voltage in the main circuit
Description : A reverse-current relay will prevent AC generator motorization by ____________. A. automatically redirecting the load B. automatically speeding up the prime mover C. tripping the panel board main switch D. tripping the generator circuit breaker
Description : You are paralleling two alternators. The synchronizing lamps grow dim and are totally darkened as the synchroscope pointer approaches the 0° position. This indicates that the ____________. A. alternator ... be closed C. incoming alternator is running too slowly D. synchroscope is defective or broken
Description : In an emergency, the fastest way to interrupt power and stop the winch shown in the illustration is for the ____________. EL-0102 A. mate to open the disconnect switch at 'L1' and 'L2' B. ... watch engineer to open the winch circuit breaker D. electrician to open the test link at the controller
Description : When the operating handle of a molded-case circuit breaker is in the mid-position, the circuit breaker is indicated as being ____________. A. in the 'closed' position B. in the 'opened' position C. tripped D. reset
Description : The symbol shown as figure 'A' represents a/an ____________. EL-0059 A. transformer B. coil C. shunt field D. inductor
Description : The wiring diagram for the motor starting circuit shown in the illustration indicates ______________. EL-0007 A. resistance starting B. reduced voltage starting C. low voltage protection D. low voltage release
Description : The direction of rotation of a DC propulsion motor can be reversed by __________. A. reversing the field connections B. reversing the field and the armature connections C. wiring the field and armature in parallel D. wiring the field and armature in series
Description : A bus disconnect link is used to isolate _____________. A. one bus bar from another B. the generator circuit breaker from the bus C. different phases from the equalizer connection D. positive and negative buses from the neutral
Description : Under normal conditions, the speed of a two-speed squirrel cage induction motor is changed by varying the ____________. A. frequency of the applied voltage B. resistance in the rotor circuit C. number of field poles D. amplitude of the applied voltage
Description : Which of the methods listed is used to maintain the division of load between two compound-wound, DC generators operating in parallel? A. The shunt fields are interconnected. B. The shunt ... generators are connected in series. D. The equalizer connection parallels the series fields of all machines.
Description : The electrical diagram shown in the illustration represents a ___________. EL-0054 A. series-wound motor B. shunt-wound motor C. compound-wound motor D. flat-compounded motor
Description : Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out? A. De-energize the applicable switchboard bus. B. Bypass the interlocks. C. ... supply circuit breaker in the open position. D. Station a man at the circuit supply switch.
Description : To remove an alternator operating in parallel with another unit from the main electrical bus, you must FIRST _________. A. adjust the power factor on both units B. set the desired voltage on ... C. open the circuit breaker on the outgoing alternator D. remove the load from the outgoing alternator
Description : Electrical circuits are protected against overheating by means of a/an ______________. A. circuit breaker B. amplifier C. diode D. capacitor
Description : A device used in an electrical circuit to change alternating current to direct current, is known as a _____________. A. current transformer B. rectifier C. condenser D. shunt
Description : With which of the following, a circuit breaker must be equipped for remote operation ? (a) Inverse time trip (b) Time-delay trip (c) Shunt trip (d) None of the above (e) All of the above
Last Answer : (c) Shunt trip