Sistemas eléctricos II

51. Why are the iron cores of most induction coils laminated?. To reduce the core reluctance. To increase the core permeability. To reduce the effects of eddy currents. Energize the armature.

52. Which statement relating to electric wiring is true?. When attaching a terminal to the end of an electric cable, it should be determined that the strength of the cable-to-terminal joint is at least twice the tensile strength of the cable. electrical unit in the circuit and should be located as close to the source as possible. All electric cable splices should be covered with soft insulating tubing (spaghetti) for mechanical protection against external abrasion. When attaching a terminal to the end of an electric cable, it should be determined that the strength of the cable-to-terminal joint is at least equal to the tensile strength of the cable itself.

53. Which of the following should be accomplished in the installation of aircraft wiring?. Support the bundle to structure and/ or solid fluid lines to prevent chafing damage. Provide adequate slack in the wire bundle to compensate for large changes in temperature. Locate the bundle above flammable fluid lines and securely clamp to structure. only plain nuts and lockwashers have been used for terminal attachment to the studs.

54.Which of the following must be accomplished when installing an anticollision light?. Install a switch independent of the position light switch. Use shielded electrical cable to assure fail-safe operation. Connect the anticollision light to the aircraft position light switch. The number of turns of wire in the coil and the applied voltage.

55. Which of the following copper electrical cable sizes should be selected to replace a No. 6 aluminum electrical cable?. No. 4. No. 6. No. 8. No. 10.

56. Where electric cables must pass through holes in bulkheads, formers, ribs, firewalls, etc., the wires should be protected from chafing by. wrapping with electrical tape. using a suitable grommet. wrapping with plastic. wiring from too much voltage.

57. When using the voltage drop method of checking circuit resistance, the. input voltage must be maintained at a constant value. output voltage must be maintained at a constant value. input voltage must be varied. the voltage and amperage of the load it must carry.

58. When using an ohmmeter to check the continuity of a generator field coil, the coil should. be removed from the generator housing. show high resistance when the meter prods are connected to the terminals of the coil. show very low resistance if it is a series field coil. opening the shunt field circuit.

59. When necessary during operation, CSD disconnect is usually accomplished by. a switch in the cockpit. circuit breaker activation. a shear section in the input shaft. the component has continuity and is not open.

60. When dc generators are operated in parallel to supply power for a single load, their controls include an equalizer circuit to assure that all generators share the load equally. The equalizer circuit operates by. increasing the output of the low generator to equal the output of the high generator. decreasing the output of the high generator to equal the output of the low generator. increasing the output of the low generator and decreasing the output of the high generator until they are equal. total effective field strength by changing the reluctance of the magnetic circuit.

61. When considering an alteration, the criteria upon which the selection of electric cable size should be based are. applied voltage and allowable voltage drop. current-carrying capacity and allowable voltage drop. current-carrying capacity and applied voltage. The current exceeds a predetermined value.

62. When adding a rheostat to a light circuit to control the light intensity, it should be connected in. parallel with the light. series with the light. series parallel with the light switch. parallel with the switch.

63. What protection to wires and cables does conduit provide when used in aircraft installations?. Electromagnetic. Mechanical. Structural. Chemical.

64. What kind of switch should you install in a single wire circuit that required the switch to be manually held in the ON position?. Single-pole, single-throw (SPST), two- position normally open (NO). Single-pole, single-throw (SPST), single-position. Single-pole, double-throw (SPDT), single-position normally open (NO). Dual-pole, single-throw (DPST), single-position.

65. What is the voltage drop for a No. 18 copper wire 50 feet long to carry 12.5 amperes, continuous operation? Use the formula VD = RLA VD = Voltage drop R = Resistance per ft = .00644 L = Length of wire A = Amperes. 1/2V. 1V. 4V. 2V.

66. What is the ratio of turns between the primary coil winding and the secondary coil winding of a transformer designed to triple its input voltage?. Primary will have one-third as many turns as its secondary. Primary will have twice as many turns as its secondary. Primary will have three times as many turns as its secondary. Both fields are shunted across the armature.

67. What is the purpose of the selection of derated switches for known continuous load current applications?. To calculate the voltage drop across the circuit. To prevent short circuits in the motor field windings. To obtain reasonable switch efficiency and service life. The current exceeds a predetermined value.

68. What is the maximum amount of time a circuit can be in operation and still be an intermittent duty circuit?. Three minutes. Two minutes. One minute. Ten minutes.

69. What is the frequency of an alternator dependent upon?. Voltage. RPM. Current. Watts.

70. What is the advantage of a current limiter?. It breaks circuit quickly. It can be reset easily. It will take overload for a short period. Always eliminates the need of a switch.

71. What is the advantage of a circuit breaker when compared to a fuse?. Never needs replacing. Always eliminates the need of a switch. Resettable and reusable. It breaks circuit quickly.

72. What is normally used to bond noncontinuous stainless steel aircraft components?. Stainless steel jumpers. Copper jumpers. Aluminum jumpers. Iron steel copper.

73. What is an important factor in selecting aircraft fuses?. The current exceeds a predetermined value. The voltage rating should be lower than the maximum circuit voltage. Capacity matches the needs of the circuit. greater ease in stepping the voltage up or down.

74. What is a method used for restoring generator field residual magnetism?. Flash the fields. Reseat the brushes. Energize the armature. show very low resistance if it is a series field coil.

75. Un propósito de la puerta de inducidos (growler test) es para determinar la presencia de. Un conmutador con deformación circunferencial. Un cable de campo roto. Una armadura en corto. Ranurado.

76. To help minimize radio interference a capacitor will largely eliminate and provide a steady direct current if the capacitor is connected to the generator in. parallel. series. series/parallel. series/parallel.

77. The voltage output of an alternator may be regulated by controlling the. speed of the alternator. voltage output of the dc exciter. resistance in the rotor windings. dusting the cable with powdered soapstone.

78. The voltage in an ac transformer secondary that contains twice as many loops as the primary will be. greater and the amperage less than in the primary. greater and the amperage greater than in the primary. less and the amperage greater than in the primary. by means of a rectifier.

79. The three kinds of circuit-protection devices used most commonly in aircraft circuits are. circuit breakers, resistors, and current limiters. circuit breakers, fuses, and current limiters. circuit breakers, capacitors, and current limiter plug-ins mechanical reset types. wrapping with electrical tape.

81. The strength of the core of an electromagnet depends upon the material from which it is constructed and which of the following?. The number of turns of wire in the coil and the applied voltage. The number of turns of wire in the coil and the amount of current (amperes) passing through the coil. The size (cross section) and the number of turns of wire in the coil and the applied voltage. resistance in the generator output circuit.

82. The purpose of a rectifier in an electrical system is to change. the frequency of alternating current. direct current to alternating current. alternating current to direct current. Real power is zero.

83. The primary considerations when selecting electric cable size are. current-carrying capacity and allowable voltage drop. the voltage and amperage of the load it must carry. the system voltage and cable length. input voltage must be maintained at a constant value.

84. The poles of a generator are laminated to. reduce flux losses. increase flux concentration. reduce eddy current losses. an infinitely variable mechanical gearing system.

85. The pin section of an AN/MS connector is normally installed on. the power supply side of a circuit. the ground side of a circuit. either side of a circuit (makes no difference). resistance in the rotor windings.

86. The overvoltage control automatically protects the generator system when excessive voltage is present by. opening the shunt field circuit. opening and resetting the field control relay. breaking a circuit to the trip coil of the field control relay. increasing the output of the low generator to equal the output of the high generator.

87. The nominal rating of electrical switches refers to continuous. current rating with the contacts open. voltage rating with the contacts closed. current rating with the contacts closed. the system voltage and cable length.

88. The most common method of regulating the voltage output of a compound dc generator is to vary the. current flowing through the shunt field coils. total effective field strength by changing the reluctance of the magnetic circuit. resistance of the series field circuit. Rotate the positive brush one commutator segment.

89. The most common method of attaching a pin or socket to an individual wire in an MS electrical connector is by. crimping. soldering. crimping and soldering. Rolling.

90. The major advantages of alternating current (AC) over direct current (DC) is the fact that its current and voltage can easily be increased or decreased. by means of a inverter. by means of a rectifier. by means of a transformer. be removed from the generator housing.

91. The inductor-type inverter output voltage is controlled by the. number of poles and the speed of the motor. voltage regulator. dc stator field current. resistance of the generator field circuit.

92. The generator rating is usually found stamped on the. firewall. generator. engine. Energy.

93. The circuit breaker in the instrument lighting system protects the. lights from too much current. wiring from too much current. wiring from too much voltage. inverters which use the aircraft's ac generators as a source of power.

94. Terminales de alhambre eléctrico para la mayoría de las aplicaciones de aeronaves deben ser del tipo. Ranurado. Gancho. Anillo. Obturado.

95. Si un generador está equipado con un regulador de voltaje de tipo vibrador, el único momento en que los puntos del vibrador permanecen abiertos. La potencia de salida del motor pueda ser controlada de mas cerca. Está controlado por la separación (clearance) de los puntos del relay de corte de corriente inversa. Es aumentada cuando la carga externa es mayor que la salida del generador. Depende en la carga que lleva el generador.

96. Residual voltage is a result of magnetism in the. field windings. field shoes. armature. an integral fan.

97. Para que el relé de salida del generador se cierre deben cumplirse dos condiciones: Que se ponga el interruptor correspondiente de cabina en ON y que lo permita el panel de control. Que se ponga el interruptor correspondiente de cabina en RESET y que lo permita el panel de control. Que lo permita el panel de control y que el APU este disponible. Que lo permita el panel de control y que la EXTERNAL POWER este disponible.

98. One advantage of using ac electrical power in aircraft is. that ac electrical motors can be reversed while dc motors cannot. greater ease in stepping the voltage up or down. that the effective voltage is 1.41 times the maximum instantaneous voltage; therefore, less power input is required. rectifiers which use the aircraft's ac generators as a source of power.

99. Oil canning of the sides of aluminum or steel electrical junction boxes is considered to be. normal operation in vibration prone areas. a shorting hazard. acceptable operation. Structural.

100. Los generadores del avión, generalmente se encuentran ubicados en: Los motores. En el sistema Neumático. En el sistema hidráulico. En los alojamientos de los trenes de aterrizaje.