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
Last Answer : Answer: C
Description : A loss of field excitation to an AC generator while operating in parallel will cause it to ____________. A. absorb more and more load due to decreased armature reaction B. lose its load due to ... polarity D. lose its load, begin to motorize, trip out on reverse power relay, and possibly overspeed
Last Answer : Answer: D
Description : The timer element of a reverse power relay cannot be energized unless _____________. A. the power flow is the same as the tripping direction B. the power flow is the opposite to the tripping direction C. the movement of the disk is damped by a permanent magnet D. one generator is motorized
Last Answer : Answer: A
Description : The timer element of a reverse power relay cannot be energized unless _____________. A. one generator is fully motorized B. the movement of the disk is damped by a permanent magnet C. the power flow is the same as the tripping direction D. the power flow is the opposite to the tripping direction
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 : Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in ... . governor speed droop setting B. voltage regulator C. balance coil D. phase-balance relay
Last Answer : Answer: B
Description : 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 switch
Description : A constant output voltage from an AC generator is maintained by the _____________. A. prime mover governor B. exciter generator C. voltage regulator D. reverse power relay
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 : The division of the kilowatt load between two AC generators operating in parallel is controlled by the settings and characteristics of the _____________. A. voltage regulators B. field rheostats C. reverse power relays D. prime mover governors
Description : If a three-phase induction motor malfunctions and drops to a single-phase (one supply line open) ____________. A. the motor will continue to run if it is not heavily loaded B. more torque will be ... be able to be restarted D. the motor will immediately stop and can only be restarted at no load
Description : In order to safely carry out repairs to a generator circuit breaker, it must be isolated from the bus. This is accomplished by opening the _____________. A. reverse power relay B. bus disconnect link C. generator bus fuse connections D. power directional relay
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 : When paralleling two AC generators, the frequency of the machine coming online, immediately prior to closing its breaker, should be ____________. A. slightly less than the oncoming generator frequency B. the ... bus frequency C. slightly greater than the bus frequency D. the same as the bus voltage
Description : When paralleling two AC generators, the frequency of the incoming machine immediately prior to closing its breaker should be ____________. A. controlled by placing the governor switch in the automatic ... regulator C. slightly greater than the bus frequency D. slightly less than the bus frequency
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 : When paralleling two AC generators, the synchroscope selector switch and frequency meter switch should be set up to sense the frequency of the _____________. A. bus B. generator on the line C. oncoming generator D. bus transfer relay
Description : Which of the following is/are true concerning electric power operated watertight door systems? A. Each motor driven door must use the main bus as its source of power. B. Each distribution panel for ... to permit quick activation of the system. D. Each system must have a separate branch circuit.
Description : The heaters for the winch circuit shown in the illustration are powered from _____________. EL-0102 A. a separate source B. the winch main bus C. the master switch power circuit D. the contactor control circuit
Description : If the centrifugal switch or relay used for cutting out the starting winding of a split-phase induction motor fails to open once the motor is in operation, the _____________. A. motor will overspeed B ... C. motor will immediately stall under load D. motor torque will be above normal at rated speed
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 : An alternator operating in parallel begins to vibrate severely and eventually trips out on the reverse power relay. The cause of the vibration was a result of ______________________. A. the ... C. the alternator was operating out of synchronism D. flashover at the alternator collector rings
Description : In a 15 HP induction-type motor with a cage rotor, the current required at standstill to produce starting torque is approximately ____________. A. half the full load current B. equal to the full load current C. five times the full load current D. ten to twenty times the full load current
Description : An AC generator operating in parallel loses its excitation without tripping the circuit breaker. This will __________. A. not affect the faulty generator due to the compensation of the other generators B. ... between the armature and the bus D. cause high currents to be induced in the field windings
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 : 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 : Power necessary to operate the horn relay shown in the illustration ____________. EL-0093 A. comes from each station's magneto B. is supplied from a 115 volt source C. is conducted through the relay's contacts D. also lights lamps 'R' and 'T'
Description : You are reconnecting a three-phase induction motor to the supply line. To prevent possible damage to the load, due to the wrong direction of rotation, you should ____________. ... supply line phase sequence and motor rotation with appropriate indicators, then connect correspondingly marked leads
Description : The purpose of the reverse power relay, provided on a ship's service alternator panel, is to trip the circuit in the event of ______________. A. main circuit overload B. high power transfer C. generator overspeeding D. alternator motorization
Description : When an operating motor is connected to the controller shown in the illustration, the a path of current flow through the circuit is ____________. EL-0010 A. 'L1', stop button, start button, coil 'CR', 'L2' B. 'L1' ... L2' D. 'L1', stop button, start button, 'CR' contact, 'M' contact, 'CR' coil, 'L2'
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 : An operating characteristic appearing on the name plates of shipboard AC motors is _____________. A. the type of winding B. input kilowatts C. temperature rise D. locked rotor torque
Description : Why is it a good practice to have the frequency of the incoming alternator adjusted slightly higher than that of the loaded alternator when paralleling two alternators? A. This allows the oncoming machine to ... line. C. The reverse power relay is prevented from activating. D. All of the above.
Description : In the illustration, if one of the devices labeled 'TURB' should fail the ___________. EL-0003 A. device labeled 'EXC' will drive the alternator B. device labeled 'BKR' for that ... -alternator D. emergency generator should automatically start and be placed on line to supply emergency load centers
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
Description : The most efficient torque — producing actuating structure for induction — type relay is:
Last Answer : The most efficient torque — producing actuating structure for induction — type relay is: induction-cup structure
Description : In induction type directional over current relay the driving torque is due to interaction of magnetic fields derived from (A) current in the potential coil (B) both voltage and current in the ... (C) directional element and non-directional element (D) non-directional element and the trip circuit
Last Answer : In induction type directional over current relay the driving torque is due to interaction of magnetic fields derived from directional element and non-directional element
Last Answer : The torque produced in induction type relay (shaded pole structure) is inversely proportional to the square of the current.
Description : The most common source of excitation for synchronous motors is a/an _____________. A. low voltage battery B. motor attenuator set C. DC exciter generator D. AC supply
Description : You are attempting to parallel two AC generators and the synchroscope pointer is revolving slowly in the fast direction. You should _____________. A. use the governor control switch to adjust the incoming ... the 0° position D. use the field rheostat to adjust the speed of the incoming machine
Description : The purpose of a short circuit forcing module (short time trip) installed in a branch line is to provide ____________. A. high speed clearance of low impedance short circuits in the branch B. ... C. isolation of short circuits by selective tripping of branch circuit breakers D. all of the above
Description : Starting torque can be obtained in the case of a single phase induction motor with identical main and auxiliary windings by connecting: (1) A capacitor across the mains (2) A capacitor in ... with the auxiliary winding (4) Equal value capacitors in series with the main and the auxiliary windings
Last Answer : Starting torque can be obtained in the case of a single phase induction motor with identical main and auxiliary windings by connecting: A capacitor is series with the auxiliary winding.
Description : A characteristic of a wound-rotor induction motor, with a high resistance rotor winding, is _____________. A. low starting torque B. high starting torque C. high speed D. low starting voltage
Description : If an induction motor were to be operated at 90% rated voltage, _____________. A. there would be an increase in starting torque B. starting current would increase slightly C. synchronous speed would decrease slightly D. the slip would increase
Description : 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
Description : The leads from a megohmmeter are attached to the leads of an AC motor field coil. A reading of infinity is obtained indicating a/an ____________. A. open field coil B. shorted field coil C. grounded field coil D. shunted field coil
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 : Humming or buzzing of electric contacts is a symptom of ____________. A. low voltage on the operating coil B. power failure to the operating coil C. a control circuit ground D. a control circuit overload
Description : The device in figure 'B' shown in the illustration will conduct when the ____________. EL-0067 A. base-emitter is forward biased and the collector-base is reverse biased B. anode-cathode is forward ... is reversed biased D. terminal 1-2 is forward biased and the emitter-terminal 1 is reverse biased
Description : The function of the autotransformers used with the starters of large AC motors is to provide _____________. A. increased voltage for starting B. increased torque for starting C. reduced voltage for starting D. speed control