- The type of electric wire terminals used for most aircraft applications, in addition to providing good carrying capabilities, are designed primarily-- to prevent circuit failure due to terminal disconnection.
- To test generator or motor armature windings for opens,--Place armature in a growler and connect a 110V test light on adjacent segments, light should lit.
- What is the color & orientation of the position lights for navigation on civil airplanes?--Left side-red, Right side- green, Rear aft- white.
- To what depth is the mica insulation between the commutator bars of a dc generator undercut?-- Equal to the width of the mica.
- A voltage regulator controls generator output by-- Varying current flow to generator field coil.
- Which type of dc generator is not used as an airplane generator?-- Series wound.
- What is the most accurate type of frequency- measuring instrument?- Integrated circuit chip having a clock circuit.
- During ground operation, aircraft generator cooling is usually accomplished by--An integral fan.
- What does a rectifier do?- Changes AC into DC.
- What type of instrument is used to measuring very high values of resistance?- Megohmmeter.
- When a diode is checked for an open circuit or a short circuit, it should be-- Disconnected from the circuit.
- When handling a high voltage capacitor in an electrical circuit, be sure it--Is fully discharged before removing it from the circuit.
- Cause of Thermal-Runaway in a Ni-Cd battery-- Excessive current draw from the battery.
- How can it be determined if a transfomer winding has some of its turns shorted together?--The transformer will get hot in normal operation.
- For general electrical use in aircraft, the acceptance method of attaching a terminal to a wire is by--Crimping.
Monday, August 11, 2014
FAA regulated questions part-1
FAA regulated questions..
- Some electric motors have 2 sets of field windings wound in opposite directions so that the--Motor can be operated in either direction.
- One purpose of growler test is to determine the presence of-- A shorted armature.
- Electric wire terminals for most aircraft applications must be what type?-- Ring type.
- Principle advantage of the Series wound DC motor--- High Starting Torque.
- If a generator is equipped with a vibrator-type voltage regulator, the actual time the voltage regulator points remains open---Depends on the load carried by the generator.
- What is the cause of generator brush arcing?-- Low Spring Tension.
- When AC generators are operated in parallel, the--- Frequency and Voltage must be equal.
- The starting current of a series-wound DC motor, in passing through both the field and armature windings produces a--- High Starting Torque.
- Which motor would bee most likely to have an armature brake?-- Landing light Retraction Motor.
- The method most often used in overcoming the effect of armature reaction is through the use of--Interpoles.
- The only practical method of maintaining a constant voltage output from an aircraft generator under varying conditions of speed and load is to vary the-- Strength of the magnetic field.
- The pole pieces or shoes used in a DC generator are a part of the-- Field assembly.
- How many cycles of AC voltage are produced in a six-pole alternator of the revolving-field type for each revolution of the rotor?-- Three
- If the reverse current cut-out relay( RCCR) contact points fall to open after the generator output has dropped below battery potential, current will flow through the generator armature-- Opposite the normal direction and through the shunt field in the normal direction.
- How does the magnetic brake used to stop rotation of an electric motor armature operate?-- A friction brake is applied by a spring and released by a magnet.
- In a generator, what eliminates any possible sparking to the brush guides caused by the movement of the brushes within the holder?-- The Brush Pigtail.
- A series-wound DC electric motor will normally require--More current at low RPM than at high RPM.
- Aluminium wire must be stripped very carefully because-- Individual strands will break easily after being nicked.
- The commutator of a generator-- Changes AC produced in the armature into DC as it taken from the armature.
- An ammeter in a battery charging system is for the purpose of indicating the-- Rate of current used to charge the battery.
- Not the purpose of interpoles in a generator----- Reduce Field Strength.
Saturday, August 9, 2014
Notes on Electrical system-2
- Purpose of Trickle charging of batteries- To keep it fresh and fully charged.
- Capacity of Lead-acid battery doesnt' depends upon- Rate of charge.
- Internal resistance of battery is reduced by- a)Increase the size of the plate,
b) Multiply the number of plates, c) Interlacing of plates.
- Efficiency of battery is increased by- 5 hour Discharge Rate.
- Batteries are rapidly charged by- Constant Voltage & Variable Current.
- Neutralizing agent of Lead-acid battery are- Baking Soda & Water.
- The electrolyte in Ni-Cd batteries performs work as a- Conductor, but not take part in chemical reaction.
- Electrolyte in Ni-Cd battery is- Pottasium Hydroxide( KoH).
- CSD( Constant Speed Drive) is disconnected - Electromechanically.
- In CSD, the UNDERDRIVE condition, pressure will be- Increases.
- Main purpose of using core in a transformer--- Decrease reluctance of common magnetic circuit.
- Transformer is not used as an Amplifier because- It doesn't provide Power Gain.
- Lamination of a transformer depends upon-- Frequency.
- An electric motor in which both the rotor and the stator field rotates with the same speed is called-- Synchronous Motor.
- For parallel operation, AC polyphase altenator must have the same-- Voltage Rating.
- What will happen, if we interchange two phases of a three phase induction motor?-- The direction of rotation will be reversed.
- Type of motor used in direct cranking of engine-- DC Series Wound.
- Thickness of laminations reduced in a transformer to- Reduce Eddy Current.
- Operating current of LED-- 20 to 30 mA.
- In Double squirrel cage Induction motor the outer stage has-- High Resistance.
- Electrostatic Voltmeter measures-- AC & DC.
- An aircraft battery requires frequent addition of water due to-- Leakage & Defective cell.
- What is the value of capacitor with colour coding Red, Green,Black & Grey?-- 25pF
- The average value of unsymmetrical alternating current is considered across- 1 Complete Cycle.
- What is not essential condition for parallel operation of 2 one phase transformer, is that they should have the --- Same Polarity.
- If the primary of step-up transformer is connected to load by mistake and secondary is supplied with voltage--- It will act as step-down transformer.
- Operation of LCD-- It doesn't emit light & depends on light falling on it.
- In a PN junction, the depletion layer is formed due to-- Mobilization of majority carrier.
- The APU serves the purpose of- Supplying electrical and pneumatic power as required.
- The main field of the generator in the brushless alternator is excited from-- Field connected to the rotating rectifier.
- Flashing of field is not required in brushless alternator because Percent voltage build up is achieved by--DC supply from GCU, is supplied continuously.
- A VTVM produces negligible loading effect on a circuit under a test because- Of its very high internal resistance.
- When servicing a DC generator, a dark film is found on commutator--It should be cleaned with no.000 sand paper.
- The dirt on the NI-Cd battery is cleaned with- De mineralized water.
- The meter used to measure the voltage of individual cells of the battery-- Normal Voltmeter.
- In CRO, what actually is done by varying intensity control-- Negative Grid base.
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