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
Last Answer : Answer: D
Description : When shore power is being connected to a ship in dry dock, _____________. A. the ship's generators are paralleled with the shore power to provide continuous power B. proper phase sequence must be ... 450 volts must be supplied from the shore D. exactly 60 Hz must be provided by the terminal
Last Answer : Answer: B
Description : If there is a reduction in the normally supplied frequency to a 120/240 volt, threephase AC current motor from 60 hertz to 55 hertz, the motor would _____________. A. run at a slower speed B. operate at a lower current C. overheat D. trip off the line
Last Answer : Answer: A
Description : Which of the following procedures should be used to determine the load of a threephase, delta wound, AC generator? A. Multiply the amperage in one phase by three. B. Divide the total amperage in all ... square root of three. D. Divide the total amperage in all phases by the square root of three.
Last Answer : Answer: C
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 : Two single-phase 150 kVA, 7200/ 600 volt transformers are connected in open-delta. The maximum three-phase load that they can carry is: A) 300 kVA B) 75 kVA C) 259 kVA D) 249 kVA
Last Answer : Two single-phase 150 kVA, 7200/ 600 volt transformers are connected in open-delta. The maximum three-phase load that they can carry is: 259 kVA
Description : What type of equipment normally uses 26-volt 400-hertz synchros?
Last Answer : . Aircraft.
Description : Which of the listed sections of an emergency switchboard is used to supply power for alarm signals under emergency conditions? A. The generator and bus transfer section B. The 450 volt, 60 cycle, 3 phase bus C. The 120 volt, 3 phase, 60 cycle bus D. The 24 volt DC bus
Description : Consider the following statements regarding three-phase transformers in Open -Delta (V -V) connections : 1. Being a temporary remedy when one transformer forms of Delta -Delta system is &imaged, and removed from service. ... and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3
Last Answer : Consider the following statements regarding three-phase transformers in Open -Delta (V -V) connections : 1. Being a temporary remedy when one transformer forms of Delta -Delta system is &imaged, and removed from service. ... and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3
Description : Voltage generated by most AC generators is fed from the machine to the bus by means of ____________. A. brushes on a commutator B. brushes on slip rings C. slip rings on a commutator D. direct connections from the stator
Description : To reverse the direction of rotation of a three-phase AC induction motor, do one of the following: w) reverse any two of the three-phase connections x) change the frequency of the applied AC power y) operate the motor below the stall torque at very high slip z) none of the above
Last Answer : ANSWER: W -- REVERSE ANY TWO OF THE THREE-PHASE CONNECTIONS
Description : One important difference between wye-connected and delta-connected generators is that delta connections have ____________. A. line voltages equal to the vector sum of the phase voltages B. phase voltages 90° ... C. line current equal to the phase current D. line voltage equal to the phase voltage
Description : AC and DC generators are similar in that they _____________. A. both generate alternating voltages B. both rectify the voltage before delivery C. are constructed at the same physical size for the same kilowatt rating D. both supply three-phase power
Description : Which of the listed transformer uses a single winding to produce voltage transformation? A. Stepup transformers B. Stepdown transformers C. Autotransformers D. Isolation transformers
Description : Draw neat labeled diagram of single phase AC locomotive showing its various equipments of power circuit and give function of each equipment used in power circuit.
Last Answer : Functions of equipment: 1) circuit breaker: disconnects the locomotive equipment from the supply in the event of fault in the equipment / loco. 2) On load tap changer, used to control the ... 6) Traction motor: operates as per the required operating characteristics to take on the traction load.
Description : Generators convert mechanical motion to electrical energy using what principle?
Last Answer : Magnetic induction
Description : Why are most ships limited in their ability to stock replacement modules for repair of electronic equipment?
Last Answer : Lack of adequate storage space.
Description : The plate voltage of a tube will vary 126 volts when a 3-volt ac signal is applied to the control grid. What is the gain of this tube?
Last Answer : 42.
Description : What is the basic difference between the primaries of ac and dc rate generators?
Last Answer : The method of primary excitation (ac and permanent magnet).
Description : Can Transformers develop Three Phase power from a Single Phase source?
Last Answer : A. NO. Phase converters or phase shifting devices such as reactors and capacitors are required to convert single phase power to three phase.
Last Answer : No. Phase converters or phase shifting devices such as reactors and capacitors are required to convert single phase power to three phase.
Description : [23] Transformers are rated in KVA instead of KW because A. load power factor is often not known B. KVA is fixed whereas KW depends on load power factor C. Total transformer loss depends on volt ampere D. It has become customary
Last Answer : C. Total transformer loss depends on volt ampere
Description : A shore power circuit breaker should be closed only _____________. A. when the ship's generators have been directly paralleled to those on shore B. in a shipyard C. if a quick disconnect coupling is used D. when the ship's generators have been removed from the bus
Description : Range-marker generators produce pulses based on what radar constant?
Last Answer : The radar mile (12.36 microseconds).
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 : If the illustrated motor fails to start and gives a loud hum when the start button is pushed, the problem is ________. EL-0007 A. one of the phases to the motor is not energized because of ... electrical distribution system D. 'OL1' is open because of 'T1' overload causing the motor to single phase
Description : The division of the reactive KVA load between paralleled AC generators is initiated by the ______________. A. prime mover governors B. voltage regulators C. phase balance relay D. proportioner
Description : When paralleled, AC generators must have the same _________. A. frequency B. number of phases C. phase rotation D. all of the above
Description : You are attempting to parallel two AC generators, and the synchroscope pointer is revolving fast in the clockwise direction. This indicates that the frequency of the incoming machine is _____________. A. higher ... at any pointer position D. the same as the bus frequency but out of phase with it
Description : You are attempting to parallel two AC generators, and the synchroscope pointer is revolving in the fast direction. This indicates that the frequency of the incoming machine is _____________. A. higher ... the same as the bus frequency and the circuit breaker may be closed at any pointer position
Description : While paralleling two (2) AC generators using synchronizing lamps only, both lamps will go dark when the generators are ____________. A. running at the same speed B. grounded C. of the same polarity D. in phase
Description : You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0° prior to closing the circuit breaker. This indicates ___________. A. the frequency of ... be closed after breaker has been reset D. there is an existing cross current between generators
Description : You are attempting to parallel two AC generators and the synchroscope pointer is revolving in the slow direction. This indicates that the frequency of the incoming machine is _____________. A. higher than ... same as the bus frequency, and the circuit breaker may be closed at any pointer position
Description : Can Single Phase Transformers be used for Three Phase applications?
Last Answer : A. Yes. Three phase transformers are sometimes not readily available whereas single phase transformers can generally be found in stock. Three single phase transformers can be used in delta connected primary and ... K VA single phase transformers can be used to accommodate a 30 KVA three phase load.
Description : A three-phase transformer, connected in star-delta, is composed of three single-phase transformers, each rated 127/ 13.2 kV. The line-to-line voltage ratio for the three-phase transformer is: A) 220 / 13.2 kV B) 127 / 13.2 kV C) 127 / 220 kV D) 220 / 220 kV
Last Answer : A three-phase transformer, connected in star-delta, is composed of three single-phase transformers, each rated 127/ 13.2 kV. The line-to-line voltage ratio for the three-phase transformer is: 220 / 13.2 kV
Description : An additional condition for parallel operation of three-phase transformers over single-phase transformers is that
Last Answer : An additional condition for parallel operation of three-phase transformers over single-phase transformers is that the transformers should belong to the same vector group
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 : When troubleshooting a console circuit card suspected of being faulty, first check for proper voltages to the card and then _______________. A. test transistors or integrated circuits for gain and ... D. de-energize the card and check the printed circuit traces for continuity with an ohmmeter
Description : We use single and three phase generators not two phase generator .Why?
Last Answer : In an electrical distribution system power is delivered via three wires, each operating 120 degrees from the other. This is a 3-phase system. As the voltage gets lowered to residential areas, there is ... the two coils in parallel you can create a higher output 120V system which is single phase.
Description : A vessel is equipped with two ship's service generators. Generator #1 is rated at 900 kw and generator #2 is rated at 600 kw. During parallel operation, with a hotel load of 1,000 kw, what should be the kw load on generator #2? A. 100 kw B. 400 kw C. 500 kw D. 600 kw
Description : A diesel driven emergency generator is prevented from being paralleled with the ship's service generators by __________. A. an electrical interlock system B. an automatic paralleling trip switch C. the synchronizing oscilloscope D. the reverse current relay
Description : As a result of a mechanical malfunction in one of the ship's service generators operating in parallel, you must secure that generator. In order to prevent a possible overload to the ... feeder circuit breakers, the malfunctioning prime mover turbine throttle trip, and the generator circuit breaker.
Description : Straight silicon steel (containing Si from 0.5 to 5%) because of their low hysteresis loss and high magnetic permeability are used for electrical appliances. Which of the following electrical ... /generators (B) Generators and small motors (C) Induction motors (D) High frequency transformers
Last Answer : (D) High frequency transformers
Description : The under voltage relay can be used for (a) generators (b) busbars (c) transformers (d) motors (e) all of the above
Last Answer : (e) all of the above
Description : For which of the following protection from negative sequence currents is provided ? (a) Generators (b) Motors (c) Transmission line (d) Transformers
Last Answer : (a) Generators
Description : Electro-mechanical voltage regulators are generally used in (a) reactors (b) generators (c) transformers (d) all of the above
Last Answer : (b) generators
Description : The ground detection system, shown in the illustration for a low-voltage, threephase system has a ground in line 'A'. Therefore, lamp 'A' will burn ____________. EL-0009 A. dimly or be out, and lamps 'B' and ... and 'C' will burn dimly or be out D. brightly, and lamps 'B' and 'C' will burn normally
Description : Why should you avoid using ac-powered test equipment when wearing a wrist strap?
Last Answer : For your own safety.
Description : The frequency response of test equipment refers to what aspect of ac voltage measurements?
Last Answer : the range of frequencies that can accurately be measured.
Description : A three-phase alternator is operating at 450 volts, 250 amps at 0.6 power factor. If the power factor increases to 0.8, the kw load potential will increase by _____________. A. 38.525 kw B. 116.91 kw C. 155.88 kw D. 194.85 kw