Description : Which of the listed instruments can be best used to locate a grounded field coil in a synchronous motor? A. Frequency meter B. Megohmmeter C. Voltmeter D. Multimeter
Last Answer : Answer: B
Description : Which of the instruments listed should always be connected in series with a circuit? A. Ammeter B. Megohmmeter C. Wattmeter D. Voltmeter
Last Answer : Answer: A
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 : 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 : Aboard ship, a grounded field coil in an AC motor can be determined by using a _________________. A. portable growler B. galvanometer C. visual inspection D. megohmmeter
Last Answer : Answer: D
Description : An internal resistance is placed in series with the meter movement of which of the following instruments? A. AC ammeter B. DC ammeter C. DC voltmeter D. Frequency meter
Last Answer : Answer: C
Description : In order to increase its range of measurement, a resistance would be placed in series with which of the following instruments? A. DC voltmeter B. DC ammeter C. frequency meter D. power factor meter
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 : When a megohmmeter is being used on a alternating current machine, the meter pointer will dip toward 'zero' and then gradually rise to the true resistance value if the motor insulation is _____________. A. grounded B. good C. shorted D. dirty
Description : A useful instrument for checking A.C. motor performance by measuring possible unbalanced currents is the _____________. A. hand or battery-operated megger B. vibrating-reed frequency meter C. hook-on voltmeter-ammeter D. D'Arsonval iron-vane probe
Description : Which of the listed meters uses a shunt connected in series with the load, but parallel with the meter movement? A. Voltmeter B. Power factor meter C. Ammeter D. Wattmeter
Description : The basic meter movement responds to the flow of current through its coil. Therefore, this meter movement may be used as a/an _____________. A. voltmeter by placing a resistance in parallel with the ... in parallel with the coil D. ammeter by placing a low resistance in parallel with the coil
Description : A megohmmeter can be used to test for ____________. A. an open field coil B. synchronous speed C. undercut mica D. reversed polarity
Description : In which of the situations listed will a megohmmeter give the most accurate readings? A. While the machine is in operation. B. While the machine is discharging static electricity. C. Immediately prior to ... machine. D. When the machine has been shut down and grounded for a period of 15 minutes.
Description : 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 above
Description : Which of the instruments listed is used to check insulation resistance? A. Magneto B. Megohmmeter C. Dynamometer D. Rheostat
Description : To test fuses in an energized circuit, you should use a ____________. A. low voltage light bulb B. megohmmeter C. voltmeter D. resistance meter
Description : A short in the shunt field of a DC motor is best located by _____________. A. visual inspection of the commutator B. applying AC voltage to each field coil and measuring the voltage drop across ... using a growler and hacksaw blade D. isolating each coil from the others and using a megohmmeter
Description : Which of the meters listed should only be used after a circuit has been electrically disconnected? A. Wattmeter B. Frequency meter C. Ammeter D. Ohmmeter
Description : An open armature connection in a DC propulsion motor could be caused by ____________. A. low-load operation B. clogged ventilation ducts C. sparking at the brushes D. a grounded shunt field coil
Description : To determine if a stator coil is grounded, you should use a/an _____________. A. ammeter B. ground detection lamp C. magneto D. megger
Description : Which of the following instruments should never have their test leads connected directly to a wall outlet: w) ammeter x) voltmeter y) oscilloscope z) frequency counter
Last Answer : ANSWER: W -- AMMETER
Description : A voltmeter located on a control panel has been operating correctly for six months, suddenly burns out. After removing it, it is found that neither side of the meter has been grounded. When ... side and the ground C. installed exactly as the old installation D. grounded to the positive side
Description : The RPM of an AC generator can be measured with a/an _____________. A. ammeter B. voltmeter C. vibrating reed meter D. synchroscope
Description : Which of the following meters uses a shunt connected in series with the load, but parallel with the meter movement? A. voltmeter B. power factor meter C. wattmeter D. ammeter
Description : Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency? A. A four-pole synchronous motor under normal load. B. A four-pole induction motor under ... A six-pole synchronous motor under normal load. D. A six-pole induction motor under full load.
Description : An increase in which of the listed conditions will increase the speed of a synchronous motor? A. Frequency B. Voltage C. Armature current D. Inductance
Description : A megohmmeter is connected to each end of an individual motor winding. A low ohm reading indicates ____________. A. an open coil B. a loose coil C. good continuity D. a dirty coil
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 : Which of the listed electrical devices is represented by the symbol shown in the illustration? EL-0055 A. Fixed resistance resistor B. Coil with magnetic core C. DC motor or generator shunt field D. Transformer
Description : The final step in testing a circuit for a ground involves the use of a megohmmeter. A grounded switch or cable will be indicated by a megohmmeter reading of ____________. A. 'zero' B. infinity C. steady in the high range D. unsteady in the low range
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 : Before testing insulation with a megohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to the test as the ______________. A. insulation may be damaged ... number of leakage paths D. larger machines may acquire a charge of static electricity during operation
Description : Before testing insulation with a megohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to the test, because the ___________. A. static charge of the machine ... number of leakage paths C. insulation may be damaged D. insulation may be covered with moisture
Description : A grounded switch or cable will be indicated by a megohmmeter reading of _____________. A. infinity B. 'zero' C. being unsteady in the high range D. being unsteady in the low range
Description : A testing device called a 'growler' is being used to locate a shorted coil in the stator of an AC electrical machine. When the 'feeler' is moved over a slot containing the shorted coil _____________. ... . the meter needle will be deflected to zero D. the meter needle will be deflected to full-scale
Description : A device which can be used to check the calibration of a circuit breaker is a _________________. A. 500 volt megohmmeter B. portable low voltage high current testing unit C. standard digital multimeter D. clamp-on voltmeter
Description : In the illustrated motor controller, the motor fails to start. A voltmeter reading between 1 and 6 reads line voltage, while the voltmeter reading between 2 and 6 reads 0 VAC. The problem is __________. EL- ... in the 'M' coil, 'Ma' contact/start switch or overload contacts D. fuse '10a' is blown
Description : An open shunt field in a direct current machine may be located by connecting the field circuit to an external power source, equal to the rated field voltage or less, and tested with a voltmeter from ... C. any suitable ground to any available line lead D. any field pole to each field coil lead
Description : The speed of a synchronous motor is varied by _____________. A. interchanging any two of the three live leads B. changing the voltage of the system C. changing the input frequency D. increasing the field excitation
Description : The synchronous speed of an induction motor is the ________. A. speed at which the rotor turns B. speed of the rotating field C. frequency of the rotor current D. slip in per cent of rotor RPM
Description : Before servicing the device indicated as 'A' in panels #1 and #3 of the illustration, the device labeled 'CT' must __________. EL-0003 A. have the disconnected leads taped to prevent ... D. have one lead grounded to discharge static electricity for the prevention of damage to electronic components
Description : What is the direction of current through the load resistor in the circuit shown in the illustration? EL-0085 A. Always from point 'Z' to the grounded end. B. Always from the grounded end to ... on the instantaneous polarity at point 'W'. D. It cannot be determined without a directional ammeter.
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 listed procedures is the best way to tell if a motor has become overloaded? A. Measure the current flow and compare it with the motor full load current flow as shown on the nameplate. ... Watch for telltale signs of smoke coming from the motor. D. Periodic opening of the O/L relay coil
Description : A three-phase, induction-type motor experiences an open in one phase. Which of the listed automatic protective devices will prevent the machine from being damaged? A. Overspeed trip B. Thermal overload relay C. Three-pole safety switch D. Magnetic blowout coil
Description : Instruments of Measure The device used ' for the measurement of current, voltage and resistance is: A. AVO meter B. Galvanometer C. Ammeter D. Ohm meter
Last Answer : ANSWER: A
Description : A capacitor is to be tested with a megohmmeter. If the meter is connected to a shorted capacitor, the meter pointer should _____________. A. immediately swing to the maximum resistance value ... and gradually decrease D. swing to zero then gradually increase with slight pointer movements down scale
Description : Which of the following statements represents the action of a megohmmeter when testing a small capacitor in good condition? A. The meter pointer should immediately swing to the maximum resistance value ... . D. The meter pointer should immediately swing to a high reading and gradually decrease.
Description : A capacitor can be tested using a megohmmeter or an ohmmeter. If the meter is connected to a shorted capacitor, the meter pointer should _____________. A. immediately swing to the maximum resistance ... deflect to and remain at zero D. immediately swing to a high reading and then gradually decrease