Description : Time delayed or delayed action-type fuses are designed to _____________. A. prevent grounds in branch circuits B. prevent opens in motor circuits C. permit momentary overloads without melting D. guard lighting and electronic circuits
Last Answer : Answer: C
Description : As shown in the illustration, the circuit has been on the line for several days when component 'E1' burns out. The operator receives an alarm, switches over 'B' to energize the standby ... than required for the circuit therefore limiting the current through the alarm relay which will not pick up
Last Answer : Answer: D
Description : In addition to short circuits and sustained overloads, fuses are likely to blow due to _____________. A. loose fuse clips B. low ambient temperatures C. low contact resistance D. all of the above
Last Answer : Answer: A
Description : To check the three line fuses of a three-phase system consisting of a three-phase motor, you must _____________. A. place the starter in the 'stop' position B. make sure the motor is operating at full ... leads across the 'hot' ends of the fuses D. place the leads across the bottom ends of the fuses
Description : Transformers are used onboard ships with AC generators to _____________. A. change frequency B. increase power output to modulating frequency controllers C. decrease power output to modulating frequency ... D. permit higher voltage for electric motor operation and low voltage for lighting circuits
Description : The shipboard general alarm system must receive its main source of power from _____________. A. a storage battery B. the emergency generator C. an auxiliary generator D. the ship's service generator
Description : The diagram shown in the illustration represents a _________. EL-0058 A. dual speed, 2-winding motor controller B. navigation running light circuit C. single phase, 2-motor selectable starter D. common fluorescent lighting circuit
Last Answer : Answer: B
Description : A delayed-action fuse is most frequently used in which of the listed circuits? A. Lighting circuit B. Motor circuit C. Electric heater circuit D. Radar circuit
Description : The devices marked 'T' in the illustration are _____________. EL-0080 A. trouble alarm units whose contacts activate when problems arise either on starting or stopping of the motor B. topping ... contactor parts whose contacts start and stop the defrosting cycle of the compressor driven by the motor
Description : Since the characteristics of the device shown in figure 'A' of the illustration includes a stable voltage and low current while operating, it can be suitably used in _____________. EL-0065 A. oscillators ... . class A and B amplifiers C. generator rectifier and filtering supplies D. all of the above
Description : Upon failure of the normal power supply, the emergency generator is placed on the line by the _____________. A. main bus tie feeder B. automatic bus transfer device C. line connection feeder D. power failure alarm bus
Description : RC time constant characteristics, as shown in the illustration, are important in _____________. EL-0086 A. bridge rectifiers for alternator excitation B. timing and pulse shaping circuits C. transistor power amplifier biasing D. motor controller overload protection
Description : AC circuits possess characteristics of resistance, inductance, and capacitance. The capacitive reactance of a circuit is expressed in _____________. A. ohms B. mhos C. henrys D. farads
Description : Autotransformer starters or compensators are sometimes used with polyphase induction motors to _____________. A. reduce the voltage applied to the motor during the starting period B. increase the voltage for ' ... to be either stepped up or down, depending on the application, to ensure full torque
Description : A low-voltage protection circuit is used in electric motor starting equipment to _____________. A. trip circuit contactors when the motor overspeeds due to low voltage B. trip circuit ... voltage without manually resetting D. prevent the motor from restarting automatically on restoration of voltage
Description : The 24 volt DC bus on the emergency switchboard is used to supply power to the _____________. A. general alarm system B. gyrocompass power failure alarm system C. smoke detection system D. all of the above
Description : Diesel generators #1 and #2 are operating in parallel at near full load capacity. Diesel generator #1 suddenly trips out mechanically due to low lube oil pressure. The reverse power relay functions ... all nonvital circuits. D. Secure alarms, reset reverse power relay, and restart #1 engine.
Description : When supplying emergency lighting loads, the storage battery initial voltage must not exceed the standard system voltage by more than _____________. A. 2% B. 3% C. 5% D. 10%
Description : The main difference between a motor control circuit containing low voltage protection and low voltage release is that the latter contains _____________. A. a magnetic operating coil B. normally open line contacts C. thermal-overload protection D. a momentary-contact start button
Description : Multiple grounds have developed and were initialy indicated by the grounddetecting system as one ground. The FIRST step in locating the grounds is to _____________. A. examine the main bus bars ... no longer indicates any grounds C. change over generators D. check each circuit with a megohmmeter
Description : The electrical energy necessary to transmit a person's voice over a sound-powered telephone circuit is obtained from _____________. A. dry cell batteries B. the ship's service switchboard C. the emergency switchboard D. the speaker's voice
Description : Fuses placed in series with a thermal trip-type circuit breaker are used for _____________. A. time-delay protection B. short-circuit protection C. short duration surge protection D. sustained overload protection
Description : According to Coast Guard Regulation (46 CFR) for emergency power and lighting systems, which of the listed items is the only permissible starting aid for the emergency diesel generator engine? A. Ether B. Lube oil heater C. Jacket water heater D. Fuel oil heater
Description : Coast Guard Regulations (46 CFR) require that each alternating current generator arranged for parallel operation shall be provided with _____________. A. more than one means of excitation B. individual circuit fuses C. a high back-pressure trip D. a reverse-power trip
Description : Excessive heat in an operating motor controller can result from _____________. A. a closed starter contact B. loose connections C. missing arc chutes D. low motor starting torque
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 : The electrical energy necessary to power a sound-powered telephone's small vibrating bell is obtained from _________. A. the emergency batteries for the general alarm B. each station's hand-cranked generator C. the emergency switchboard D. normal 115 volt DC supplies
Description : Upon failure of the normal power supply, the emergency generator is placed on the line by the _____________. A. bus tie feeder B. automatic bus transfer device C. line connection feeder D. power failure alarm bus
Description : If the motor shown in the illustration will not start when 'Q' is depressed, which of the listed components should be checked FIRST? EL-0017 A. Fuses 'F-1' and 'F-2'. B. Operating coil 'C'. C. Contacts 'H-1', 'H-2', and 'H-3'. D. Contact 'H-4'.
Description : Which of the following conditions is most likely to occur if a single element fuse were used to replace a blown dual element fuse in a motor controller circuit? A. The fuse will blow when the motor ... overheats at high motor loads. C. The motor runs at reduced voltage. D. The motor runs normally.
Description : Coast Guard Regulations (46 CFR) require manual contactors for operating the general emergency alarm on tank vessels to be located in the navigating bridge, engine room and the ____________. A ... C. crew accommodations and sleeping spaces D. engineering officers' quarters furthest from the bridge
Description : In a faceplate-type motor starter, the starting arm is held in the 'OFF' position by a/an _____________. A. cotter pin B. magnet C. electrical circuit D. strong spring
Description : Two paralleled alternators are operating near rated load. If one trips out mechanically, which of the listed actions should be taken FIRST? A. Restart the tripped machine immediately. B. Strip the board ... circuits. C. Start the emergency generator. D. Transfer all vital loads to the emergency bus.
Description : Basic operating characteristics of the operational amplifier such as gain and stability are the function of its _____________. A. differential input stage B. power output stage C. feedback circuit D. supply voltages
Description : A device which prints out a permanent record of the plant operating conditions is known as the _____________. A. analogger B. bell logger C. alarm logger D. data logger
Description : When testing for blown fuses in a three-phase supply circuit to a motor, you should first ___________________. A. apply the megger across the tops of the line fuses B. apply an ammeter diagonally across ... of the line fuses D. ensure the circuit is de-energized, and then use a continuity tester
Description : You are using a mechanical voltage tester to check the fuses in a three-phase circuit supplying an electric motor. For which of the following reasons must the motor be stopped during the test? A. ... circuit would be indicated by the voltage tester with the circuit energized. D. All of the above.
Description : Which of the following actions must be carried out before a voltage tester can be used to test the three line fuses to a three-phase motor? A. The fuses must be removed from the circuit. B. The ... disconnected and tagged. D. Nothing need be done as long as the motor is running under a light load.
Description : The main purpose of the auxiliary winding on a split-phase, single-phase motor is to _____________. A. limit the starting voltage B. increase the starting current C. start the motor D. keep the motor running in the event the main winding should fail
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
Description : Federal Regulations (46 CFR) require the circuit in the illustration to _________. EL-0009 A. be at the vessel's ship's service generator distribution switchboard for normal power, normal lighting ... ground will interfere with the operation of electronic equipment D. All the above are correct
Description : The electrical schematic shown in the illustration indicates the lighting feeder circuit is _____________. EL-0014 A. three phase, 450 volt, and 60 cycle B. three phase, 120 volt, and 60 cycle C. single phase, 120 volt, and 60 cycle D. not specified
Description : The source of emergency lighting and power at loss of normal ship's power on a cargo vessel should be obtained from the ______________. A. emergency generator supply to the emergency ... switchboard C. battery supply to the main switchboard D. turbogenerator supply to the emergency switchboard
Description : The purpose of the automatic bus transfer shown in the illustration is to ___________. EL-0014 A. stepdown voltage to the lighting distribution panel B. provide emergency power to ... emergency switchboard from the main switchboard D. provide overcurrent protection to the lighting distribution panel
Description : In the illustrated one line diagram, if the turbo generator fails, the diesel generator_________. EL-0014 A. will automaticly start and supply power to the emergency power switchboard, the power ... be manually started but once running will supply power to the lighting main through the ABT.
Description : The devices labeled 'L' in the illustration are _________. EL-0003 A. load lights indicating that the generator breaker is closed and the generator is supplying power to the main bus B. ... o'clock position the lights are at their dimmest or out indicating the the generators are in phase
Description : The timer element found in a reverse power relay obtains its operating torque via _____________. A. line voltage B. the main bus C. electromagnets D. a separate battery source
Description : The standard procedure for maintaining the charge in an emergency diesel starting battery is to trickle charge the battery _____________. A. continuously B. at least once each week C. whenever the charge falls to 75% of full charge D. whenever the electrolyte specific gravity falls to 1.250 or lower
Description : Electric strip heaters are used in motor controllers to _____________. A. prevent freezing of movable contacts B. keep the components at their design ambient temperature C. prevent condensation of moisture D. minimize resistance in internal circuits
Description : As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to _____________. A. draw a one line diagram of the circuitry B. test all fuses and measure the line voltage C. take megger readings D. insulate the apparatus from ground