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TECHGEN-BNC-MODULE8
1.
(For this question use annex 021- 6660A) The logic symbol shown represents (assuming positive logic):
a) a NOR gate.
b) an EXCLUSIVE gate.
c) an INVERT or NOT gate.
d) a NAND gate.
2.
If the frequency of the supply in a series capacitive circuit is increased, the current flowing in the circuit will:
a) increase.
b) decrease.
c) be zero.
d) remain the same.
3.
When operating two AC generators unparalleled, the phase relationship of each generator:
a) must be in opposition.
b) is unimportant.
c) must be synchronous.
d) must be 90° out of synchronisation.
4.
The primary purpose of the bleed valves fitted to axial flow compressors is to:
a) enable an external air supply to spin up the compressor for engine starting.
b) control the acceleration time of the engine.
c) spill compressor air should the engine overspeed thus controlling the speed.
d) reduce the likelihood of compressor stall.
5.
Real load sharing in a parallel AC system is achieved by:
a) automatic adjustment of the torque on each generator rotor via the CSD unit.
b) monitoring the kVAR of each generator/alternator.
c) carefully selecting the number of loads on the bus-bars at any one time.
d) controlling the generator field current.
6.
A CSD unit which has been disconnected in flight:
a) automatically resets at engine shut-down.
b) may be reset in flight using the reset mechanism.
c) automatically resets in flight providing engine rpm is below a given value.
d) may be reset on the ground only, after engine shut-down.
7.
The function of a NOT logic gate within a circuit is to:
a) ensure the input signal is AC only.
b) ensure the input signal is DC only.
c) ensure the output signal is of the same state as the input signal.
d) invert the input signal such that the output is always of the opposite state.
8.
The services connected to a supply bus-bar are normally in:
a) parallel, so that isolation of loads decreases the bus-bar voltage.
b) series, so that isolation of loads increases the bus-bar voltage.
c) series, so that isolating one load increases the bus-bar current consumption.
d) parallel, so that isolating individual loads decreases the bus-bar current consumption.
9.
If two constant frequency AC generators are operating independently, then the phase relation between both generators:
a) must be synchronised.
b) must be 240° out of phase.
c) is unimportant.
d) must be 120° out of phase.
10.
Because of the input/output relationship of an AND gate, it is often referred to as the:
a) "inhibited" or "negated" gate.
b) "state indicator" gate.
c) "all or nothing" gate.
d) "any or all" gate.
11.
When AC generators are operated in parallel, they must be of the same:
a) amperage and kVAR.
b) voltage and amperage.
c) frequency and amperage.
d) voltage and frequency.
12.
Circuit breakers protecting circuits may be:
a) used only in AC circuits.
b) reset at any time.
c) used only in DC circuits.
d) used in AC and DC circuits.
13.
When two DC generators are operating in parallel, control of load sharing is achieved by:
a) carrying out systematic load-shedding procedures.
b) the synchronous bus-bar.
c) an equalising circuit which, in conjunction with the voltage regulators, varies the field excitation current of the generators.
d) an equalising circuit which, in turn, controls the speed of the generators.
14.
A CSD of an AC generator may be disconnected in flight. The primary reason(s) for disconnection are:
a) excessive variation of voltage and kVAR.
b) illumination of the CSD disconnect warning light.
c) low oil pressure and/or high oil temperature of the generator drive.
d) slight variation about the normal operating frequency.
15.
On an aeroplane utilising AC as primary power supplies, the batteries are charged in flight from:
a) a static inverter.
b) a DC transformer and rectifier.
c) the AC bus via current limiters.
d) a Transformer Rectifier Unit.
16.
A cabin pressure controller maintains a pre-set cabin altitude by regulating the:
a) mass air flow into the cabin.
b) position of the outflow valve(s).
c) position of the duct relief valve(s).
d) position of the inward relief valve.
17.
Immediately after starting engine(s) with no other electrical services switched on, an ammeter showing a high charge rate to the battery:
a) indicates a generator failure, thus requiring the engine to be shut down immediately.
b) indicates a battery failure since there should be no immediate charge.
c) indicates a faulty reverse current relay.
d) would be normal and is only cause for concern if the high charge rate persists.
18.
The purpose of a voltage regulator is to control the output voltage of the:
a) output of the TRU.
b) generators at varying speeds and the batteries at varying loads.
c) generator at varying loads and speeds.
d) batteries at varying loads.
19.
A bus-bar is:
a) a device permitting operation of two or more switches together.
b) the stator of a moving coil instrument.
c) a distribution point for electrical power.
d) a device which may only be used in DC circuits.
20.
"Conditioned" air is air that has:
a) had any moisture removed from it.
b) had the oxygen content reduced.
c) been controlled in respect of temperature and pressure.
d) had the oxygen content increased.
21.
"Frequency wild" in relation to a AC generation system means the generator:
a) voltage regulator is out of adjustment.
b) output frequency is too low.
c) output frequency is too high.
d) output frequency varies with engine speed.
22.
When carrying out battery condition check using the aircraft's voltmeter:
a) a load should be applied to the battery in order to give a better indication of condition.
b) no load should be applied to the battery because it would depress the voltage.
c) the load condition is unimportant.
d) the battery should be isolated.
23.
The purpose of bonding the metallic parts of an aircraft is to:
a) prevent electrolytic corrosion between mating surfaces of similar metals.
b) provide a single earth for electrical devices.
c) provide safe distribution of electrical charges and currents.
d) isolate all components electrically.
24.
The capacity of a battery is expressed in terms of:
a) volts.
b) watts.
c) ampere-hours.
d) internal resistance.
25.
Because of the input/output relationship of an OR gate, it is often referred to as the:
a) "all or nothing" gate.
b) "any or all" gate.
c) "inhibited" or "negated" gate.
d) "state indicator" gate.
26.
If a current is passed through a conductor which is positioned in a magnetic field:
a) there will be no effect unless the conductor is moved.
b) the intensity of the magnetic field will decrease.
c) a force will be exerted on the conductor.
d) the current will increase.
27.
Which of the following statements, relating to the application of Ohm's Law, is the most correct?
a) current in a circuit is inversely proportional to the electromotive force.
b) power in the circuit is inversely proportional to the square of the current.
c) The current in a circuit is directly proportional to the resistance of the circuit.
d) Current in a circuit is directly proportional to the applied electromotive force.
28.
In order that DC generators will achieve equal load sharing when operating in parallel, it is necessary to ensure that:
a) adequate voltage differences exists.
b) equal loads are connected to each generator busbar before paralleling.
c) the synchronising bus-bar is disconnected from the busbar system.
d) their voltages are almost equal.
29.
When an "open circuit" occurs in an electrical supply system, the:
a) fuse or CB should isolate the circuit due to excess current drawn.
b) component will operate normally, but will not switch off.
c) loss of continuity will prevent its working components from functioning.
d) load as indicated by the ammeter will increase.
30.
Assuming a CSD fault is indicated, the CSD should be disconnected:
a) at flight idle engine rpm only.
b) provided the engine is running.
c) on the ground only.
d) when the AC generator voltage is outside limits.
31.
The function of a constant speed drive (CSD) in an AC generating system is to:
a) vary the engine rpm (within limits) to compensate for various AC loads.
b) directly maintain a constant proportion between the rpm of an engine and a generator.
c) vary generator rpm in order to compensate for various AC loads.
d) drive the generator at a constant speed.
32.
If air is tapped from a gas turbine HP compressor, the effect on the engine pressure ratio (EPR) and the exhaust gas temperature (EGT) is that:
a) EPR decreases and EGT remains constant.
b) both EPR and EGT decrease.
c) EPR remains constant and EGT increases.
d) EPR decreases and EGT increases.
33.
An AC generator driven by a CSD unit:
a) does not need a voltage controller since the CSD will ensure constant voltage.
b) does not need a voltage controller since an AC generator voltage cannot alter under load.
c) requires a voltage controller to maintain constant frequency.
d) requires a voltage controller to maintain constant voltage under load.
34.
The measured output power components of a constant frequency AC system are:
a) kVA and kVAR.
b) volts and amperes.
c) amperes and kilowatts.
d) volts and kilowatts.
35.
Turbine blade stages may be classed as either "impulse" or "reaction". In an impulse blade section:
a) the pressure rises across the nozzle guide vanes and remains constant across the rotor blades.
b) the pressure drops across the nozzle guide vanes and remains constant across the rotor blades.
c) the pressure remains constant across the nozzle guide vanes and drops across the rotor blades.
d) the pressure remains constant across the nozzle guide vanes and rises constant across the rotor blades.
36.
A current limiter fuse in a DC generation system is used to:
a) instantaneously rupture to limit the current in the load.
b) limit the current in the field circuit.
c) allow a short term overload before rupturing.
d) limit the current in the armature.
37.
The frequency of an AC generator is dependent on the:
a) number of pairs of poles and the speed of the moving part.
b) field strength and the speed of the moving part.
c) number of individual poles and the field strength.
d) number of individual poles only.
38.
The function of a CSD in an AC generating system is to:
a) vary the engine rpm (within limits) to compensate for various AC loads.
b) drive the generator at a constant speed.
c) directly maintain a constant proportion between the rpm of engine and generator.
d) vary generator rpm in order to compensate for various AC loads.
39.
In an aircraft equipped with a DC main power system, AC for instrument operation may be obtained from:
a) a rectifier.
b) a TRU.
c) an inverter.
d) a contactor.
40.
Connecting two 12 volt 40 ampere-hour capacity batteries in series will result in a total voltage and capacity respectively of:
a) 12 volts, 40 ampere-hours.
b) 24 volts, 40 ampere-hours.
c) 24 volts, 80 ampere-hours.
d) 12 volts, 80 ampere-hours.
41.
When a conductor cuts the flux of a magnetic field:
a) current will flow in accordance with Flemings left hand rule.
b) there will be no effect on the conductor.
c) an electromotive force (EMF) is induced in the conductor.
d) the field will collapse.
42.
When a battery is almost fully discharged there is a tendency for the:
a) voltage to decrease under load.
b) electrolyte to "boil".
c) current produced to increase due to the reduced voltage.
d) voltage to increase due to the current available.
43.
The moving part in an AC generator is usually referred to as the:
a) rotor.
b) stator.
c) oscillator.
d) slip ring.
44.
A test to assess the state of charge of a lead-acid battery would involve:
a) checking the level of the electrolyte.
b) checking the discharge current of the battery "on-load".
c) comparing the "on-load" and "off-load" battery voltages.
d) checking the battery voltage "off-load".
45.
A 3 phase AC generator has 3 separate stator windings spaced at:
a) 60°.
b) 90°.
c) 45°.
d) 120°.
46.
To ensure correct load sharing between AC generators operating in parallel:
a) only real loads need to be matched.
b) both real an reactive loads must be matched.
c) the matching of loads is unimportant.
d) only reactive loads need to be matched.
47.
In an aeroplane utilising a constant frequency AC power supply, DC power is obtained from a:
a) static inverter.
b) rotary converter.
c) Transformer Rectifier Unit.
d) 3 phase current transformer unit.
48.
On the flight deck, an oil operated CSD unit is normally provided with means of monitoring the:
a) oil temperature and synchronous speed.
b) oil over-temperature and low oil pressure.
c) low oil temperature and low oil quantity.
d) output speed and oil pressure.
49.
A "trip-free" type circuit breaker is a circuit protection device which:
a) is free from the normal CB tripping characteristic.
b) can be reset at any time.
c) will not allow the contacts to be held closed while a current fault exists in the circuit.
d) will allow the contacts to be held closed in order to clear a fault in the circuit.
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