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TEST BORRADO, QUIZÁS LE INTERESE: 3272-3 Elec (3.11)

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Título del Test: 3272-3 Elec (3.11) Descripción: 3272-3 Elec (3.11) Autor: Atomo OTROS TESTS DEL AUTOR Fecha de Creación: 03/10/2024 Categoría: Geografía Número Preguntas: 62

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An advantage of a star connected generator over a delta connected generator is the line and phase voltages are equal. two potentials are available. a balance load is guaranteed. Permanent magnets in an AC generator are to provide initial excitation. to control the frequency. to rectify the current. An AC generator`s frequency will always be constant regardless of the generators drive speed. be proportional to the RPM at which it is driven. vary with changes in field strength. A frequency wild AC generator is used for any AC load. deicing loads. instruments and navigation. How many cycles of AC voltage are produced in a six-pole alternator of the revolving-field type, with each revolution of the rotor? Six. Four. Three. The variable frequency output from an AC generator is used for driving AC operated instruments. supplying non-inductive loads. the AC supply instead of using inverters. The amount of electrical power for a given generator weight is greater for AC generator. determined by the size of the aircraft. greater for DC generator. On a typical AC generator the output is taken direct from the rotor via slip rings. direct from the stator windings. direct from the exciter. An AC generator is producing the required voltage but a higher frequency than that required to remedy this, the following action must be taken? Decrease the speed of the prime mover. Decrease the speed of the prime mover, and then decrease the strength of the field. Decrease the speed of the prime mover, and then increase the strength of the field. In a 3 phase generator with balanced load, the potential between the neutral point and earth is equal to line volts. zero volts. equal to phase volts. The power output of an AC parallel generator system is measured in KW / KVARS. amperes. KVA. The shape of the output waveform of an AC generator is known as a sine wave. frequency wave. cosine wave. The sum of the instantaneous E.M.F.`s in a three phase system is three times the phase voltage. zero. equal to the line voltage. One revolution of a three phase generator will produce 1 cycle. 3 cycles. 2 cycles. The `A` phase of a three phase power system is colour coded red. blue. yellow. The tolerance of the AC generator frequency is 10 Hz. 40 Hz. 20 Hz. A generator supplies 25 A, 4 V and 50 W. What is the apparent power and the power factor? 400 VA and 0.5. 100 VA and 2 100 VA and 0.5. A conventional aircraft generator will be delta wound. series wound. star wound. Power factor of a generator is tan ø. cos ø. sin ø. In a 3 phase generator, what angle are the phases to each other? 180°. 120°. 0°. In a 2 phase generator, what angle are the phases to each other? 90°. 0°. 180°. Delta wound line current is equal to phase current. root 3 * phase current. less than the phase current. An alternator delivers 500V RMS at 1 ampere. The power factor is 0.8. The true power is 500W. 100VA. 400W. On a brushless AC generator, the main rotating field is fed with DC via diodes on the rotor. AC. AC from the rotating field exciter. Single phase components in a three phase system may be connected between phase A and B only. any phase and neutral OR between any two phases. phase and neutral only. A generator rated at 30 KVA and power factor 0.8 has a maximum continuous power output of 30 kW. 24 kW. 48 kW. If there was a mainly inductive load on an AC generator, the voltage with respect to the current would lag. be in phase. lead. On a brushless AC generator, the permanent magnet generator output is DC. pulsed. AC. The output from a rotating armature AC generator would be taken from either the rotor or the stator. the rotor. the stator. A frequency wild AC generator system has variable voltage only. variable voltage and frequency. variable frequency only. An AC generator has four poles. To produce a frequency of 400Hz it must achieve a speed of 6000 RPM. 3000 RPM. 12000 RPM. The stator of a permanent magnet rotor AC generator is usually star wound. is wound in series with the field. is usually delta wound. The power output of a similar sized 3 phase compared to a single phase generator is more. same. less. In a voltage equalising circuit the generators are regulated so the higher output is decreased to that of the lower. the lower is increased and the higher is decreased until they are equal. the lower output is increased to that of the higher. In a 3-phase delta wound circuit, line current is same as the phase current. the vectorial sum of all 3 phase currents. in phase with the phase current. In an aircraft brushless alternator the armature is in series with the field. delta wound. star wound. If the phase voltage of a star wound generator is 115V, what would be the line to line voltage? 220V. 180V. 200V. What are the factors affecting the frequency of an AC generator? Number of pole pairs and rpm. Number of turns in the armature coil and number of pole pairs. Number of turns in the armature coil and rpm. A generator with more than two phases is known as polyphase. multiphase. delta phase. A generator supplies 150VAC phase and load is 10 Ohms per phase. What is the phase current ? 25.5 A. 1.5 A. 15 A. The phases on a three phase AC generator are spaced at 120 degrees. 90 degrees. 180 degrees. Increasing the load on a permanent magnet generator will reduce the terminal voltage by a large amount. reduce the terminal voltage by a small amount. increase the terminal voltage by a small amount. Two 3 phase generators operating in parallel with different phase and line voltages will be connected in Parallel configuration. star configuration. delta configuration. The Stability windings in a 3 phase AC generator are to sense field oscillations. overvolt. phase shift. Delta wound alternator currents are the same as line current. the same as phase current. the phase current multiplied be the square root of 3. In smaller single or twin engine aircraft the primary DC power is supplied in the form of rectified output from constant frequency ac generator. inverter. frequency wild ac generator. Single phase components in a 3 phase system may be connected between any phase and earth or between any two phases. any phase and earth. phase A and B only. Under frequency in an AC supply would cause overheating of inductive devices. overspeeding of AC motors. overvoltage of capacitive devices. The line voltage of a 3 phase star connected AC generator is equal to the phase voltage. greater than the phase voltage. less than the phase voltage. In an AC generator of the brushless type the rotating field winding is fed with AC via rotating exciter windings. DC via the slip rings from an external supply. DC via diodes from the main exciter winding on the rotor. An AC generator is rated at 30 kVA at 0.8 Power Factor: this means that the maximum continuous output should not exceed 24 KW. 30 KW. 5 KW. To adjust the voltage of an AC generator, whilst maintaining constant frequency, it is necessary to alter the reactance of the starter winding circuit. alter the field current. alter the driving speed. In a Delta connected generator the line current is equal to 1.7 * phase current. 1.7 * phase voltage. phase current. An AC motor which rotates at the same speed as supply frequency is called a universal machine. a synchronous motor. an induction motor. A three phase AC motor is running at speed on constant load. If one phase goes open circuit, the motor will run at same speed. ⅓ speed. ⅔ speed. Shaded poles in an alternating current motor are intended to reduce eddy current losses. prevent overshooting. facilitate starting. In a 3 phase motor, if 1 phase is lost, the motor runs at 2 thirds speed. runs at 1 third speed. remains at the same speed. A three-phase motor has the windings 180°apart. 120° apart. 90° apart. To change the direction of a 3-phase induction motor you would swap all of the input connections. remove one of the input connections. swap two of the stator connections. A capacitor in a single phase AC motor is to provide a phase shift. prevent spikes. block DC. The slip speed of an induction motor is stator speed-rotor speed. stator speed / rotor speed. stator speed + rotor speed. An inductance/resistance motor is restricted to low loads only. less efficient than a capacitance motor. better than a capacitance motor.

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