Description : To properly use a hook-on-type volt/ammeter to check current flow, you must FIRST _____________. A. de-energize the circuit to allow connection of the instrument in series B. hook the jaws ... test leads to the appropriate terminals D. short the test leads and calibrate the instrument to zero
Last Answer : Answer: B
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 order to prevent the winch shown in the illustration from turning while troubleshooting the controller circuit, _________________. EL-0102 A. set the dynamic brake by clamping contact 'DB' closed B. set the ... at 'B1' and 'B2' D. open the test link preventing current flow to the armature
Last Answer : Answer: D
Description : A lead-acid battery is considered fully charged when the ______________. A. electrolyte gasses freely B. battery charger ammeter indicates a positive reading C. terminal voltage reaches a constant value at a ... cells reaches the correct value and no longer increases over a period of 1 to 4 hours
Description : When an alternator is to remain idle for even a few days _________________. A. lift the brushes and disconnect the pigtails B. insulate the collector rings with strips of cardboard C. energize the heater circuit D. open the equalizing bus disconnect switch
Last Answer : Answer: C
Description : What is Clamp-On Ammeter?
Last Answer : Clamp-on ammeter is used to check the current in a circuit, without being physically connected in a circuit. They are convenient to use in the field since the circuit does not have to be opened to take a current reading.
Description : In D.C. motor construction, commutating windings are wound on _________________. A. opposite main poles B. interpoles C. adjacent main poles D. the rotor core
Description : A infinite resistance is considered as a/an a) Closed path(short circuit) b) Open path c) Not defined d) Ammeter with zero reading
Last Answer : b) Open path
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
Last Answer : Answer: A
Description : Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator ... rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field
Description : Tightly knit metal braid wire can be used with a printed circuit board when ___________. A. conductor flexibility is required B. desoldering components in the circuit C. electrically produced magnetic ... cause inaccuracies in adjacent components D. reactance in the circuit must be kept to a minimum
Description : In the system shown in the illustration, the station at section I is unable to signal any other station nor is any other station able to signal the station in section I. The station can, however, ring ... only a single station to respond to itself. D. The switch at component 'C' is stuck open.
Description : Clamp on ammeter is used for measurement of:
Last Answer : Clamp on ammeter is used for measurement of: large alternating currents
Description : In the schematic diagram of the DC compound generator shown in the illustration, the positive ammeter reading is 500 amps and the negative ammeter reading is 475 amps. What is the current flow through the neutral bus? EL-0037 A. 0 amp B. 12.5 amp C. 25 amp D. 975 amp
Description : A multimeter may be damaged by taking a _____________. A. voltage reading while in the ammeter mode B. current reading while in the voltmeter mode C. resistance reading while in the ammeter mode D. resistance reading while in the voltmeter mode
Description : The hook-on AC volt-ammeter consists essentially of a split-core and a rectifiertype instrument connected to the secondary winding of a _____________. A. potential transformer B. control transformer C. current transformer D. reactance transformer
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
Description : Which of the instruments listed could be use to locate a grounded field coil in a synchronous motor? A. Ammeter B. Voltmeter C. Megohmmeter D. Frequency meter
Description : Which of the instruments listed should always be connected in series with a circuit? A. Ammeter B. Megohmmeter C. Wattmeter D. Voltmeter
Description : A load with an impedance of 440 ohms is connected across the secondary of the transformer illustrated. If the input voltage is 110 VAC and the step-up ratio is 10 to 1, what will be the primary current? EL-0055 A. 2.5 amps B. 25 amps C. 250 amps D. current cannot be determined with information given
Description : If a circuit breaker that utilizes built-in, current limiting fuses (CLF's) cannot be closed, the problem may be traced to __________. A. a blown CLF plunger holding the trip bar in the open position B. a missing CLF C. a misaligned limiter housing assembly D. all of the above
Description : When electrical cables penetrate watertight bulkheads, _______________. A. they should be grounded on either side of the bulkhead B. they must be bent to a radius of six diameters C. a watertight stuffing tube capable of accepting packing should be employed D. they should be secured by a clamp
Description : As shown in the illustration, once the "LV" relay is energized for operation, what contacts must remain closed to maintain the "LV" relay energized when the control lever is moved away from the "off" or "stop" ... . B. Reset contacts. C. Upper set of "LVa" contacts. D. Lower set of "LVa" contacts.
Description : In the lighting distribution circuit shown in the illustration, if all switches are closed and fuse 'F2' were to open, all lights on branches ____________. EL-0013 A. '1', '2', and '3' would go out B. '1' ... and '3' would burn dimly D. '1' and '3' would go out, while branch '2' would remain lit
Description : During the start-up of the circuit shown in the illustration, it is noted that the ends of component 'C' remain lighted but the tube does not illuminate. The cause of this problem is ____________. EL- ... ' is closed C. component 'C' is the wrong wattage D. component 'B' contacts are stuck closed
Description : Refering to the illustrated schematic diagram, which of the following statements is true when the motor is running in the forward direction? EL-0011 A. Normally-open contacts '4-5' are closed. B. Current ... switch. C. Normally-closed contacts 'R' are open. D. The blowout coils must be closed.
Description : In a transformer, with closed magnetic coupling between primary and secondary __ will improve: a) Efficiency b) All day efficiency c) Regulation d) None of the above
Last Answer : Ans: C
Description : There is a lamp inside a photography darkroom. When the darkroom door is closed, it is impossible to tell from outside the room whether or not the lamp is on. There are two switches outside the door of ... dark-room door one time, how can you tell which switches, if any, control the lamp? -Riddles
Last Answer : Turn the first switch on and leave it on for ten minutes. After ten minutes, turn that switch off and turn the second switch on. Open the darkroom door, and lightly (in case it is hot) touch the ... one controls the lamp. If the lamp is off, and the bulb is cool, neither switch controls the lamp.
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 : What current flows in the transformer primary when its secondary is open?
Last Answer : A. When the secondary is open, there is no current in the secondary of the transformer. The primary takes a small current I0) from the source called no-load current which has a magnetizing ... ) producing the magnetic flux and a working component (I0 cosθ0) supplying real power for iron losses.
Description : When troubleshooting a motor controller, all indications are that a relay coil should be energized. If there were no magnetic pull, with rated voltage measured across the coil, the most probable cause ... open C. auxiliary contact in series with the coil is defective D. relay armature is stuck
Description : When troubleshooting a lead-acid storage battery, a weak or dead cell is best detected by _________________. A. measuring and comparing all cells' specific gravity B. taking an open circuit ... electrolyte levels of each cell D. taking each cell's temperature with a calibrated mercury thermometer
Description : Conductor resistance may be INDIRECTLY measured by using a/an _____________. A. voltmeter only B. ammeter only C. voltmeter and an ammeter D. ohmmeter only
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 : The alarm system for an engine order telegraph uses small selsyn motors attached to the indicators. The alarm sounds when the rotors are _____________. A. in synchronous position, no current is flowing, ... and the relays are open D. not synchronized, current is flowing, and the relays are closed
Description : Booster transformer should never: a) Have fuse in the HV winding b) Be left open circuited c) Be left closed circuited d) None of the above
Last Answer : Ans: B
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 : In the circuit shown, keys `K_1` and `K_2` both are closed the ammeter reads `I_0`. But when `K_1`is open and `K_2` is closed, the ammeter reads `I_0/
Last Answer : In the circuit shown, keys `K_1` and `K_2` both are closed the ammeter reads `I_0`. But when `K_1`is open and ... A. 100,50 B. 50100 C. 0,100 D. 0,50
Description : A three-phase alternator operates at 450 volts with a power factor of 0.8. If the ammeter indicates 250 amperes, what should be the KW meter reading? A. 90.00 KW B. 127.27 KW C. 155.70 KW D. 194.85 KW
Description : A switchboard ammeter indicates a reading slightly above 'zero' when the leads are disconnected, this is caused by _____________. A. mechanical misalignment of the meter pointer B. a poor ground for the meter case C. static electricity in the air D. capacitors inside the meter storing charges
Description : Which of the following statements represents the correct method of connecting the shunt of an ammeter prior to taking a reading? A. In series with the load and in series with the meter movement. B. In ... with the meter movement. D. In parallel with the load and in parallel with the meter movement.
Description : A three-phase alternator is operating at 450 volts with the switchboard ammeter indicating 300 amps. The kw meter currently indicates 163.6 KW, with a power factor of 0.7. If the power factor increases to 0.8, the KW meter reading would increase by ___ A. 17.8 KW B. 23.2 KW C. 30.6 KW D. 37.8 KW
Description : Full scale Ammeter reading is 10 mA, Voltage across Ammeter is 100 mV. Then for 100 A measurements the power loss in the circuit is a) 1 W b) 10 W c) 100 W d) 1000 W
Last Answer : Ans: 10 W*
Description : A commutator's protective oxide film can be destroyed by _________________. A. periods of low humidity B. very low brush current density C. improper brush grade D. all of the above
Description : Impressed current cathodic protection is used on vessels instead of _________________. A. fire alarm systems B. repeated painting C. sacrificial zincs D. vacuum tube degaussing systems
Description : A current-carrying conductor making electrical contact with a wiring conduit will be indicated by a _____________. A. high switchboard wattmeter reading B. totally dark switchboard ground detecting light C. low switchboard wattmeter reading D. all of the above
Description : A current-carrying conductor makes accidental contact with a wiring conduit. This will be indicated by a _____________. A. low switchboard wattmeter reading B. high switchboard wattmeter reading C. darkened switchboard ground detecting lamp D. darkened switchboard synchronizing lamps
Description : A current carrying conductor making an electrical contact with a wiring metal conduit is indicated by a _____________. A. low switchboard wattmeter reading B. reading of 1.0 on the power factor meter C. high switchboard voltmeter reading D. totally darkened switchboard ground-detecting light
Description : When a megohmmeter is used to test insulation, the gradual rise of the pointer reading as a result of continued cranking, is caused by _____________. A. good conductor resistance B. the ... insulation C. the inductive reactance of the windings D. the dielectric-absorption effect of the insulation
Description : 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 shunt