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 : 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
Last Answer : Answer: A
Description : When 220V dc shunt alternator generating the voltage at rated value. If direction of rotation is reversed, then alternator will a) Build up its voltage with same polarity b) Build up its voltage with opposite polarity c) No build up of voltage d) None
Last Answer : Ans: No build up of voltage
Description : Severe vibration, accompanied by flashover at the collector rings of an alternator operating in parallel, is a symptom of _____________. A. reverse current motorization B. loss of synchronism C. destructive overspeeding D. reversed polarity
Description : Which of the listed conditions will occur if the polarity of the field poles and the direction of current to the brushes of a DC motor were both reversed? A. The motor would not start. ... direction of rotation of the armature would be unchanged. D. The field pole windings would become overheated.
Last Answer : Answer: C
Description : Which of the following statements describes what will happen when both the polarity of the field poles, and the direction of current to the brushes of a DC motor are reversed? A. The motor will ... of rotation of the armature will remain the same. D. The field pole windings will become overheated.
Description : The specific gravity of the electrolyte solution in a lead acid battery _____________. A. is not effected during charging B. remains the same during discharge C. would read close to 1.830 when discharged D. gives an indication of the state of charge of the battery
Last Answer : Answer: D
Description : A megohmmeter can be used to test for _____________. A. an open field coil B. a shorted field pole C. undercut mica D. reversed polarity
Description : Violent gassing from a lead-acid battery while it is being charged, indicates that the _____________. A. plate separators are grounded B. battery compartment ventilation is inadequate C. electrolyte specific gravity is too low D. charging rate is too high
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
Description : According to Coast Guard Regulations (46 CFR), which of the following systems must be arranged so as to be energized by the final emergency power source? A. at least one light in the ... operated watertight door system C. each charging panel for temporary emergency batteries D. all of the above
Description : An equalizing connection between two compound-wound DC generators when paralleled, serves to _____________. A. reverse the polarity of the incoming generator as the series field weakens B. automatically ... the series field of the incoming generator D. parallel the series fields of the generators
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 : Caution must be exercised during the charging of lead-acid storage batteries as _____________. A. the acid will become weaker B. hydrogen gas is being continuously liberated C. both plates are changing chemically to lead sulfate D. lead peroxide in the negative plate is poisonous
Description : If violent gassing occurs when a lead-acid storage battery is first placed on charge, the _____________. A. battery must be given an emergency charge B. charging rate is too low C. charging rate is too high D. specific gravity of the electrolyte solution is too low
Description : The direction of rotation of the winch shown in the illustration is changed by reversing the _____________. EL-0102 A. direction of current through the shunt field B. polarity of voltage at 'S1' and 'S2' C. direction of current through the armature D. polarity of voltage at 'L1' and 'L2'
Description : Which of the following precautions should be taken when troubleshooting various power circuits using a common solenoid-type mechanical voltage tester (wiggins)? A. Never use this tester on circuits greater ... voltage expected in the circuit in order to prevent damage from an off-scale reading.
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 : When a lead-acid battery begins gassing freely while receiving a normal charge, the charging current should _____________. A. be increased B. remain unchanged C. be decreased D. shut off
Description : When a lead-acid battery begins gassing freely while receiving a normal charge, the charging current should be _____________. A. increased B. shut off C. decreased D. unchanged
Description : A nickel-cadmium battery is receiving a normal charge and gases freely. The charging current should _____________. A. be increased B. be decreased C. be cut off and the battery allowed to cool D. remain the same
Description : If the connections for the field and the armature on a DC motor are reversed, _____________. A. the motor will run as a generator B. the motor will not run C. the direction of rotation will be the same D. the direction of rotation will be reversed
Description : A lead-acid battery may become hotter than normal during a charge if the _________. A. battery has a shorted cell B. charging voltage is too low C. specific gravity is too high D. battery room door is secured
Description : When lead-acid batteries are charging, they always give off hydrogen gas that is _____________. A. considered inert B. highly explosive C. extremely toxic D. heavier than air
Description : When three-phase AC power is supplied to the device shown in the illustration, the output will be _____________. EL-0063 A. single-phase AC B. split-phase AC C. three-phase DC D. unidirectional DC
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 : Which of the following statements of Coast Guard Regulations (46 CFR) concerning battery installations is correct? A. Sign, permanently secured to the battery trays, indicating that 'naked lights or smoking is ... on the bottom. D. Power and lighting batteries must be of the lead-acid type only.
Description : Which of the following procedures represents the best method to prevent the freezing of batteries continuously exposed to low temperatures? A. The battery caps should be removed. B. The battery cap ... in a fully charged condition. D. The battery should be disconnected from its charging source.
Description : When charging lead-acid batteries, the charging rate should be reduced as the battery nears its full charge to ____________. A. prevent damaging battery plates B. allow equalization of cell voltages C. reduce lead sulfate deposits D. increase lead peroxide formation
Description : During the charging process of storage batteries, the charging rooms should be well ventilated because __________. A. without ventilation excessive gassing will occur B. highly poisonous gases are ... gases will otherwise accumulate D. without ventilation the battery will not take a full charge
Description : Regarding battery charging rooms, ventilation should be provided __________. A. at the lowest point of the room B. horizontally near the batteries C. at the highest point of the room D. only when charging is in progress
Description : Which of the following statements concerning nickel-cadmium batteries is true? A. When mixing electrolyte always add acid to the water. B. Nickel-cadmium batteries can be charged and ... The electrolyte of an idle nickel-cadmium battery must be replaced monthly to maintain battery condition.
Description : When charging lead-acid batteries, you should reduce the charging rate as the battery nears its full charge capacity to ______________. A. prevent excessive gassing and overheating B. allow equalization of cell voltages C. reduce lead sulfate deposits D. increase lead peroxide formation
Description : The speed of a multi-speed, squirrel-cage, induction motor operating in a fixed frequency system can be changed by _____________. A. reconnecting stator windings for different numbers of poles B. ... sequence of the applied voltage D. reconnecting the stator so that no poles have the same polarity
Description : A megohmmeter can be used to test for ____________. A. an open field coil B. synchronous speed C. undercut mica D. reversed polarity
Description : A slow continual loss of electrolyte level from one cell of a storage battery could be due to _______________. A. a cracked casing B. too low a charging rate C. the specific gravity being higher than normal D. one filler cap installed too tightly
Description : When a nickel-cadium battery begins gassing while connected to the battery charging circuit, you should _____________. A. do nothing as this is a normal condition when charging B. add distilled water ... to each cell to increase the specific gravity of the electrolyte D. decrease the charging rate
Description : Local action in a nickel-cadmium battery is offset by _____________. A. separating the positive and negative plates with plastic spacers B. separating the positive and negative plates with resin impregnated spacers C. adding a small amount of lithium hydroxide to the electrolyte D. trickle charging
Description : 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 damage
Description : What type of current would flow through the load in figure 'B' shown in the illustration? EL-0091 A. AC only B. DC only C. AC or DC depending on control winding polarity D. AC or DC depending on instantaneous polarity of the source
Description : A fuse will 'blow' if _____________. A. an electric motor is stopped suddenly by opening a switch B. the flow of current to the protection device is reversed C. the electrical current exceeds the rated value of the fuse D. unequal resistors are connected in parallel
Description : If a DC motor runs faster than designed, with all other conditions being normal, the possible cause could be a/an ______________. A. shorted shunt field coil B. open armature coil C. reversed commutating pole D. overload
Description : At high discharge rates, nickel-cadmium storage batteries are superior to lead-acid batteries because they __________. A. require fewer cells for the same voltage and less mounting space B. are able to ... times without much damage D. have no individual cells to replace at the end of useful life
Description : The electrical supply applied to the anodes shown in the illustration is _____________. EL-0090 A. low voltage, high current DC B. low voltage, high current AC C. high voltage, low current DC D. high voltage, low current AC
Description : The simplest method of controlling the terminal voltage of compound-wound DC generator is with a _____________. A. hand-operated field rheostat connected in series with the shunt field circuit B. ... in series with the load D. balance coil diverting neutral current through the shunt field
Description : The purpose of the commutator and brushes on a DC generator is to _____________. A. transfer generated direct current voltage from the armature to the line B. convert the alternating voltage ... contact method to excite the field D. reduce sparking between the armature and the carbon brushes
Description : The charging of lead-acid storage batteries will always result in __________. A. dangerous acid burns B. a dangerously explosive gas being liberated C. the danger of lead poisoning D. all of the above
Description : When used for taking resistance measurements, a volt-ohm-milliammeter is normally powered by _____________. A. a hand cranked generator B. internal storage batteries C. the current in the circuit being tested D. a step down transformer
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
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