轮机英语周考.doc

2141 When working on a high voltage circuit, you should always have another person present with you. This person should have a good working knowledge of _ A. the circuit being worked on and the location of all switches and circuit breakers controlling it B. first-aid techniques for treating electrical shock C.cardiopulmonary resuscitation (CPR) D. All of the above2140 An emergency generator, driven by an internal combustion engine, shall be tested under load for a minimum of 2 hours at least once every _ A. week B. 2 weeks C. month D. 3 months2137 The most common type of AC service generator found ship is the stationary _ A. electromagnetic field, revolving armature type B. electromagnetic field, oscillatory armature type C. armature, oscillatory electromagnet field type D. armature, rotating electromagnetic field type2134 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 itself2131 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 fans2132 A motor enclosure which protects against falling liquids is classified as _ A. waterproof B. drip proof C. spray tight D. spray proof2127 Sparking at the brushes of a running motor could be an indication of _ A. normal operation B. a dirty commutator C. increased brush capacity D. water vapor absorption2126 If a DC motor runs hot, the cause may be _ A. high mica condition B. low ambient temperature C. clogged ventilation ducts D. an open in the shunt field2123 In order to change the direction of rotation of a D.C. motor _ the field leads must be changed; the input leads must be changed A. only B. only C. either or D. both and 2120 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 grounds2116 Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine _、 A. slightly less than the line frequency B. the same as the line frequency C. slightly greater than the line frequency D. All of the above2112 To protect the rotor of a motor disassembled for maintenance or overhaul, it should be A. suspended by wire slings in one comer of the shop _ B. wrapped in several layers of heavy paper or c C. supported by flat wood blocks on the workbench D. returned to the frame as soon as the beatings are removed2113 Which of the following materials is a good insulator.?。 A. steel B. aluminum C. glass D. copper2111 When paralleled, AC generators must have the same _ A. frequency B. number of phases C. phase rotation D. All of the above21 l0 A DC generator is used to supply direct current in order to maintain an AC generator field and is known as a/an _。 A. rotor B. stator C. exciter D. armature2107 When two AC generators are being ,paralleled, the breaker should be closed with the synchroscope pointer rotating in the _ A. slow direction, just before the 12 o clock position B. fast direction, just after the 12 oclock position C. fast direction, just before the 12 oclock position D. slow direction, just after the 12 oclock position2101 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 phase2102 When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is _ A. lagging B. leading C. maximum D. minimum2103 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. lowers the insulation value and is a common cause of fault grounds in idle machines C. will enhance insulation resistance only if it is fresh water and contains no salt D. reduces the amount of current supplied or drawn by the machine so horsepower is limited2104 The voltage developed by an AC generator is controlled by varying the_ A. speed of the prime mover B. AC excitation to the field C. DC excitation to the field D. DC excitation of the voltage regulator2099 Ambient temperature is the _ A. amount of temperature rise with no load B. temperature of the compartment where the motor is located C. nomml operating temperature, less the room temperature D. amount of temperature developed by an operating motor2098 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 the bus frequency B. lower than the bus frequency C. the same as the bus frequency but out of phase with it D. the same as the bus frequency, and the circuit breaker may be closed at any pointer position2096 Voltage will always lead current in a/an _ A. capacitive circuit B. inductive circuit C. magnetic circuit D. resistive circuit2093 The frequency of an alternator is controlled from the main switchboard by adjusting the _ A. frequency meter B. voltage regulator C. governor control D. sychroscope switch2094 Complete maintenance of electrical motors should include periodic checks for machine _ A. vibration B. watertight integrity C. speed droop D. reactive power2091 Capacitance is the property of an electric circuit opposing a change in the _ A. current in the circuit B. voltage in the circuit C. inductance in the circuit D. resistance in the circuit2087 When the current in a power transmission line is increased, the power loss _ A. increases as the square of the current B. decreases as the square root of the current C. remains the same, as it is independent of current flow D. increases in direct proportion as the current2088 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. 2089 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 useful life C. energy is wasted if full loading is not utilized D. power factor correction methods are load dependent2082 The power factor of an AC generator operating singularly is determined by the _ A. connected load B, prime mover speed C. field excitation D. generators rated voltage2084 An ammeter should be used to measure _ A. the voltage between two points in a circuit B. circuit continuity C. current flow in a circuit D. total or partial circuit resistance2078 The primary function of an electric motor is to _ A. develop torque B. generate high voltages C, produce a magnetic field D. generate high electrical resistance2079 Current measuring instruments must always be connected in _ A. series with a circuit B. parallel with a circuit C. series-parallel with a circuit D. delta with the shunt2080 The total power consumed in a parallel circuit is _ A. the sum of the powers used in each load (resistor) B. divided by the number of loads C, always less than the power used in the smallest load D. the sum of the powers used in each individual load never more than the power ,used in the largest load2081 The resistance of electric wire will decrease as its _ A. length increases B. cross-sectional area increases C. temperature increases D. percent of metallic purities increases2075 Equal power factors on paralleled AC generators are maintained by an automatic _ A. voltage regulator B. reverse power relay C. reverse current relay D. governor control switch2076 If the resistance of a circuit is cut in half and the applied voltage is kept constant, the current flow will be _A. doubled B. quadrupled C. unchanged D. cut in half2077 The power factor at which a paralleled AC generator operates is usually adjusted by the _ A. connected load B. prime mover speed C. field excitation D. generators rated voltage2072 Which of the following devices are protected from being motorized by a reverse-power relay7 A. Alternators B. Wave guides C. Exciters D. Amplidynes 2073 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 speed2070 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 power2064 Prior to starting an AC generator prime mover, the voltage regulator cutout switch should be placed in the _ A. manual position B. bus neutral position C. raise voltage position D. transfer position2065 When securing an AC generator, you should FIRST _ A. open the generator circuit breaker B. switch the voltage regulator to manual C. decrease the field excitation to minimum D. reduce the load on the unit2066 When the current flow through a copper wire increases, its _ A. resistance will decrease B. insulation will bum C. temperature will increase D. conductivity will increase2068 When measuring AC current flow, you must always connect the meter _ A. in series with the power source and load B. in parallel with the power source and load C. insuring correct polarity D. using the lowest range possible to prevent instrument damage2061 When placed in a magnetic field, which of the materials listed will maintain the highest permeability?。 A. Glass B. Bakelite C. Soft iron D. Aluminum 2062 A transformer in an electric circuit serves to_ A. generate its own electrical power B. transform electrical energy into mechanical energy C. increase or decrease circuit voltage as required D. convert AC current to DC current 2063 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 shutdown C. prevent acidic pitting of the slip rings D. keep the lube oil warm for quick starting2057 For practical pmposes, in a simple series circuit, the source voltage will be dropped across one resistor if it has _ A. half the resistance of the other resistor B. a resistance equal to the other C. at least ten times the resistance of the other D. a partial short circuit2058 If both the high level and low level alarms come on for the same address of a centralized control console, the most likely problem is a/an _ 。A. sensor failure B. failed alarm C. low level D. extremely high level2059 The instantaneous reduction in voltage of an AC generator, resulting from an increase in load, and prior to the automatic voltage regulator correcting the situation, is called voltage _ A. droop B. drop C. dip D. regulation2055 The most inefficient method of voltage reduction from the stand point of power loss, is a/an _ A. capacitor in series with the load B. inductor in series with the load C. capacitor and inductor in series with the load D. resistor in series with the load2054 In a simple series circuit, the entire source voltage will drop across _ A. the resistor next to the negative terminal B. a short circuit C. the resistor next to the positive terminal D. an open circuit2051 In a three-phase circuit, the phase voltages are _ A. 120 apart B 160 apart C. 180 apart D. 360 apart2050 The frequency of an alternator at a given RPM is determined by the A. number of turns of wire in the armature coil D. governor controls B. number of magnetic poles C. strength of the magnets used2049 The pushbutton on the handset of a ships sound-powered telephone must be depressed to _ A. talk then released to listen B. listen then released to talk C. both talk and listen D. ring the station being called2048 Which of the following statements is true concerning simple parallel resistance circuits? A. The total current flow equals the sum of the individual currents. B. The total current flow equals the reciprocal of the sum of the individual currents. C. The total resistance equals the sum of the individual resistance. D. The total voltage equals the sum of the individual voltages across each resistance.2045 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 swite2047 Which of the listed items will stop a motor due to a reduction in voltage and restart it when the voltage is restored to normal? A. Low voltage protection circuit. B. Non-renewable link fuse. C. Renewable link fuse. D. Low voltage release circuit2042 A generator is prevented from becoming motorized by the use of a/an _ A. over-speed trip B. reverse power relay C. back pressure trip D. governor controls 2043 Aboard ship, a grounded field coil in an AC motor can be determined using a _ A. portable growler B. galvanometer C. visual inspection D. megohmmeter2044 Grease coatings on electrical contact surfaces increasecontact resistance and should be removed with a/an A. small wire brush B. compressed air jet C. clean dry cloth D. 10% solution carbon solvent and water2040 A switchboard, for a AC electrical distribution system, will be provided with which of the following components _ A. Frequency meter B. Ammeter C. Voltmeter D. All of the above2038 Possible phase relationships between voltage and current in an alternating current circuit include which of the following conditions.? A. Current and voltage may be in phase. B. Current may lead the voltage. C. Current may lag the voltage. D. All of the above.2034 A semiconductor is a material with a _ A. conductivity higher than a normal conductor B. conductivity higher than a normal insulator C. high conductivity at low temperatures D. low conductivity at high temperatures2035 The part of the shipboard electrical system used to control the distribution of power to the branch circuits, is the _ A. bridge control panel B. disconnect links C. governor relay box D. main switchboard2030 When you are making a high potential test on a piece of repaired electrical machinery, a rise in leakage current indicates _ A. good insulation B. bad insulation C. high insulation power factor D. a high slot discharge factor2031 The purpose of a main switchboard circuit breakers reverse-power trip is to _。 A. prevent main circuit overload B. protect the circuit breaker blowout coil C. prevent alternator motorization D. prevent low voltage tripout2032 A signal derived from a controlled function and returned to the initiating