INDIGO SYSTEMS(515-806) - Dgca question bank for pilots

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#1. The voltage of a fully charged lead-acid battery cell is :

1,8 volts.

2,2 volts.

1,4 volts

1,2 volts.

#2. Batteries are rated in :

Watts.

Amperes.hours

Amperes/volts.

Ohms.

#3. When carrying out battery condition check using the aircraft’s voltmeter :

a load should be applied to the battery in order to give a better indication of condition

the battery should be isolated

the load condition is unimportant

no load should be applied to the battery because it would depress the voltage.

#4. Connecting two 12 volt 40 ampere-hour capacity batteries in series will result in a total voltage and capacity respectively of :

24 volts, 80 ampere-hours

12 volts, 80 ampere-hours

12 volts, 40 ampere-hours.

24 volts, 40 ampere-hours

#5. The capacity of a battery is expressed in terms of :

ampere-hours

watts.

internal resistance

volts.

#6. A test to assess the state of charge of a lead-acid battery would involve :

checking the level of the electrolyte

checking the discharge current of the battery ""on-load"".

checking the battery voltage ""off-load"".

comparing the ""on-load"" and ""off-load"" battery voltages

#7. When a battery is almost fully discharged there is a tendency for the :

voltage to decrease under load.

voltage to increase due to the current available

current produced to increase due to the reduced voltage

electrolyte to ""boil"".

#8. Immediately after starting engine(s) with no other electrical services switched on, an ammeter showing a high charge rate to the battery :

indicates a faulty reverse current relay

would be normal and is only cause for concern if the high charge rate persists

indicates a battery failure since there should be no immediate charge

indicates a generator failure, thus requiring the engine to be shut down immediately

#9. A relay is :

An electromagnetically operated switch

A switch specially designed for AC circuits

An electrical security switch

An electrical energy conversion unit.

#10. A relay is :

another name for a solenoid valve

a unit which is used to convert electrical energy to heat energy.

a magnetically operated switch

a device which is used to increase electrical power.

#11. When a conductor cuts the flux of a magnetic field :

there will be no effect on the conductor

an electromotive force (EMF) is induced in the conductor

the field will collapse

current will flow in accordance with Flemings left hand rule

#12. A circuit breaker :

can be reset on the ground only

is self resetting after the fault has been rectified

may be reset manually after the fault has been rectified

can only be reset after major maintenance

#13. Circuit breakers protecting circuits may be :

used only in AC circuits

used in AC and DC circuits

reset at any time

used only in DC circuits

#14. A “”trip-free”” type circuit breaker is a circuit protection device which :

will not allow the contacts to be held closed while a current fault exists in the circuit

is free from the normal CB tripping characteristic.

can be reset at any time

will allow the contacts to be held closed in order to clear a fault in the circuit

#15. In order to produce an alternating voltage of 400 Hz, the number of poles required in an AC generator running at 6000 rpm is:

#16. In a generator, the Constant Speed Drive (CSD):1- may be disconnected from the engine shaft.2- may be disconnected from the generator.3- is a hydro-mechanical system.4- is an electronic system.5- may not be disconnected in flight.6- may be disconnected in flight.The combination regrouping all the correct statements is :

1, 4, 5

2, 3, 4

1, 3, 6

1, 2, 5

#17. In an alternator rotor coil you can find :

Only induced current

DC.

Three-phase AC.

AC.

#18. Assume a constant speed DC generator providing a constant output voltage. If the electrical load increases, the voltage regulator will :

increase the intensity of the excitation current

change the direction of the excitation current

maintain the intensity of the excitation current constant

decrease the intensity of the excitation current

#19. The essential difference between aircraft AC alternators and DC generators (dynamos) is that the:

induced windings of the alternators are rotating (rotor), and the dynamos have a rotary inductor coil

The alternators generate much less power than DC generators

induced (output) windings of the alternators are fixed (stator), and the dynamos have a fixed inductor (field) coil

alternators supply all of the output current through the commutators and brush assemblies

#20. A feeder fault on a direct current circuit results from a flux unbalance between the:

generator and the series winding turn.

shunt exciter and the series winding turn.

voltage coil and the series winding turn

voltage coil and the series winding

#21. The detection of a feeder fault on a direct current circuit results in:1. automatic disconnection of the generator from the aircraft AC busbar2. opening of generator field current relay3. opening of the main relay of the generator breaker4. opening of balancing circuit connecting two generators5. lighting of an indicator lampThe combination of correct statements is:

1, 3, 5

1, 2, 3, 4, 5

2, 3, 4, 5

2, 4, 5

#22. A DC generator fitted to a aircraft is cooled by :

air via a ram air intake

air tapped from the low pressure compressor

water at 8 degrees centrigade from the air-conditioning system.

a fan located before the generator

#23. The voltage regulator of a DC generator is connected in :

parallel with the armature

series with the shunt field coil

series with the armature

parallel with the shunt field coil

#24. The output of a generator is controlled by :

varying the field strength

varying the speed of the engine

varying the length of wire in the armature windings

the reverse current relay circuit breaker

#25. In order that DC generators will achieve equal load sharing when operating in parallel, it is necessary to ensure that :

their voltages are almost equal

the synchronising bus-bar is disconnected from the busbar system

adequate voltage differences exists

equal loads are connected to each generator busbar before paralleling.

#26. On-board electrical systems are protected against faults of the following type:1. AC generator over-voltage2. AC generator under-voltage3. over-current4. overspeed5. under-frequency6. undue vibration of AC generatorsThe combination of correct statements is :

2,3,4,5,6

1,3,5,6

1,2,4,6

1,2,4,5

#27. The frequency of the current provided by an alternator depends on…

its rotation speed

its load

the strength of the excitation current

its phase balance

#28. The function of the Generator Breaker is to close when the voltage of the :

alternator is greater than the battery voltage and to open when the opposite is true

battery is greater than the alternator voltage and to open when the opposite is true

generator is greater than battery voltage and to open when the opposite is true

battery is greater than the generator voltage and to open when the opposite is true

#29. The so-called “”hot buses”” or “”direct buses”” are:

providing an alternative current.

automatically connected to the battery if generators have failed

kept in operating conditions by an electrical resistance in the case of energy failure

directly connected to the battery

#30. The type of windings commonly used in DC starter motors are :

shunt wound

series wound

series shunt wound.

compound wound

#31. A bus-bar is :

a device which may only be used in DC circuits.

a device permitting operation of two or more switches together.

a distribution point for electrical power

the stator of a moving coil instrument

#32. When two DC generators are operating in parallel, control of load sharing is achieved by :

carrying out systematic load-shedding procedures

the synchronous bus-bar.

an equalising circuit which, in turn, controls the speed of the generators

an equalising circuit which, in conjunction with the voltage regulators, varies the field excitation current of the generators.

#33. In a two generator system, a differential relay will ensure that :

generator voltages are not equal, dependent on load

generator voltages are almost equal before the generators are paralleled.

only one generator can supply the bus-bar at a time

one generator comes ""on-line"" before the other

#34. The purpose of a battery protection unit is generally to isolate the battery:1 – from the bus when the battery charge is deemed satisfactory2 – when there is a battery overheat condition3 – in case of an internal short circuit4 – in case of a fault on the ground power unitThe combination which regroups all of the correct statements is :

1 - 2 - 3 -4

02-Jan

2001-02-03

#35. A static inverter is a:

filter against radio interference

device for reversing the polarity of the static charge

static discharger

transistorized unit used to convert DC into AC.

#36. The reason for using inverters in an electrical system is ..

To change DC into AC.

To change AC into DC.

To change the DC voltage

To avoid a short circuit.

#37. In an aircraft equipped with a DC main power system, AC for instrument operation may be obtained from :

a contactor

a rectifier

an inverter

a TRU.

#38. A unit that converts electrical DC into AC is:

an AC generator

a transformer rectifier unit.

an inverter

a thermistor

#39. Static dischargers :1. are used to set all the parts of the airframe to the same electrical potential2. are placed on wing and tail tips to facilitate electrical discharge3. are used to reset the electrostatic potential of the aircraft to a value approximating 0 volts4. are located on wing and tail tips to reduce intererence with the on-board radiocommunication systems to a minimum5. limit the risks of transfer of electrical charges between the aircraft and the electrified cloudsThe combination regrouping all the correct statements is :

1,2,5.

2,4,5.

3,4,5.

1,3,4.

#40. The advantages of grounding the negative pole of the aircraft structure are:1. Weight saving2. Easy fault detection3. Increase of short-circuit risk4. Reduction of short-circuit risk5. Circuits are not single-wired linesThe combination regrouping all the correct statements is :

1, 2, 3

2, 3, 5

1, 3, 5

1, 2, 4

#41. Electrical bonding of an aircraft is used to:1. protect the aircraft against lightning effects.2. reset the electrostatic potential of the aircraft to a value approximating 0 volt3. reduce radio interference on radiocommunication systems4. set the aircraft to a single potentialThe combination regrouping all the correct statements is:

1, 3, 4

1, 2, 3

3, 4

2, 4

#42. The purpose of static wick dischargers is to :

dissipate static charge from the aircraft skin after landing

dissipate static charge of the aircraft inflight thus avoiding radio interference as a result of static electricity

be able to fly higher because of less electrical friction

provide a path to ground for static charges when refuelling

#43. It may be determined that an aircraft is not properly bonded if :

there is heavy corrosion on the fuselage skin mountings

there is interference on the VOR receiver

static noises can be heard on the radio

a circuit breaker pops out

#44. The primary purpose of bonding the metallic parts of an aircraft is to :

isolate all components electrically and thus make the static potential constant.

provide a single earth for electrical devices

provide safe distribution of electrical charges and currents

prevent electrolytic corrosion between mating surfaces of similar metals

#45. The most widely used electrical frequency in aircraft is :

200 Hz

50 Hz.

400 Hz.

60 Hz

#46. The advantages of alternating current on board an aircraft are:1. simple connection2. high starting torque3. flexibility in use4. lighter weight of equipment5. easy to convert into direct current6. easy maintenance of machinesThe combination of correct statements is:

1, 2, 3, 4, 5, 6

1, 4, 6

3, 4, 5, 6

1, 2, 3, 5, 6

#47. If the frequency of the supply in a series capacitive circuit is increased, the current flowing in the circuit will :

increase.

decrease.

remain the same

be zero

#48. When the AC generators are connected in parallel, the reactive loads are balanced by means of the:

frequency.

energizing current

torque of the Constant Speed Drive (CSD).

voltage.

#49. The main purpose of a Constant Speed Drive unit is to:

take part in the balancing of reactive loads.

take part in the voltage regulation

maintain a constant frequency

mechanically protect the alternator drive shaft during coupling

#50. The Auxiliary Power Unit (APU) has its own AC generator which:

must have the same characteristics as the main AC generator so that it can be easily coupled with the latter

is driven at constant speed throught a Constant Speed Drive (CSD), in the same way as the main AC generator

supplies the aircraft with three-phase 115-200 V, 400 Hz AC.

is excited by its Generator Control Unit (GCU) as soon as the APU starts up

#51. In flight, if the constant speed drive (CSD) temperature indicator is in the red arc the:

pilot must disconnect it and manually control the alternator

pilot can disconnect it to allow it to cool and use it again

pilot must disconnect it, and the generator is not available for the rest of flight

pilot has to throttle back

#52. As regards the Generator Contol Unit (GCU) of an AC generator, it can be said that:1. The GCU controls the AC generator voltage2. Modern GCUs are provided with a permanent indication to record the failure3. All the commands originating from the control panel are applied via the GCU, except dog clutch release4. The Auxiliary Power Unit (APU) provides the excitation of the AC generator as soon as the APU starts upThe combination regrouping all the correct statements is :

2, 3

3, 4

2, 4

1, 3

#53. On starting, in a brushless AC generator with no commutator rings, the generator is activated by:

the auxiliary winding.

a set of permanent magnets.

the stabilizer winding jointly with the voltage regulator.

the main field winding.

#54. A CSD of an AC generator may be disconnected in flight. The primary reason(s) for disconnection are :

low oil pressure and/or high oil temperature of the generator drive

illumination of the CSD disconnect warning light

slight variation about the normal operating frequency

excessive variation of voltage and kVAR

#55. A CSD unit which has been disconnected in flight :

may be reset in flight using the reset mechanism

automatically resets in flight providing engine rpm is below a given value

automatically resets at engine shut-down

may be reset on the ground only, after engine shut-down

#56. The frequency of an AC generator is dependent upon the :

field strength and the speed of the rotor.

number of pairs of poles and the speed of the rotor

number of individual poles and the field strength

number of individual poles only

#57. The function of a constant speed drive (CSD) in an AC generating system is to :

vary the engine rpm (within limits) to compensate for various AC loads.

directly maintain a constant proportion between the rpm of an engine and a generator

vary generator rpm in order to compensate for various AC loads

drive the generator at a constant speed

#58. If two constant frequency AC generators are operating independently, then the phase relationship of each generator:

is unimportant

must be 240° out of phase

must be synchronised

must be 120° out of phase

#59. The purpose of a voltage regulator is to control the output voltage of the :

generator at varying loads and speeds

batteries at varying loads

output of the TRU.

generators at varying speeds and the batteries at varying loads

#60. A 3 phase AC generator has 3 separate stator windings spaced at :

120°.

45°.

90°.

60°.

#61. On the flight deck, an oil operated CSD unit is normally provided with means of monitoring the:

oil temperature and synchronous speed

low oil temperature and low oil quantity

output speed and oil pressure

oil over-temperature and low oil pressure

#62. An AC generator driven by a CSD unit :

does not need a voltage controller since the CSD will ensure constant voltage

does not need a voltage controller since an AC generator voltage cannot alter under load.

requires a voltage controller to maintain constant frequency

requires a voltage controller to maintain constant voltage under load

#63. Assuming a CSD fault is indicated, the CSD should be disconnected :

in accordance with the regulated voltage level of the AC generator

at flight idle engine rpm

on the ground only.

during engine operation only

#64. The measured output power components of a constant frequency AC system are :

kVA and kVAR.

volts and amperes

amperes and kilowatts.

volts and kilowatts

#65. “”Frequency wild”” in relation to a AC generation system means the generator :

voltage regulator is out of adjustment

output frequency varies with engine speed

output frequency is too high

output frequency is too low.

#66. The function of a CSD in an AC generating system is to:

drive the generator at a constant speed.

directly maintain a constant proportion between the rpm of engine and generator

vary generator rpm in order to compensate for various AC loads

vary the engine rpm (within limits) to compensate for various AC loads

#67. The frequency of an AC generator is dependent on the :

number of individual poles only

number of individual poles and the field strength

number of pairs of poles and the speed of the moving part

field strength and the speed of the moving part.

#68. Constant Speed Drive aims at ensuring

that the electric generator produces a constant frequency

that the CSD remains at a constant RPM not withstanding the generator RPM

equal AC voltage from all generators

that the starter-motor maintains a constant RPM not withstanding the acceleration of the engine

#69. A thermal circuit breaker:

forbids any overcurrent

is a protection system with a quick break capacity of about one hundredth of a second.

protects the system in the event of overheating, even without exceeding the maximum permissible current

can be reset without any danger even if the fault remains

#70. In an aircraft electrical system where AC generators are not paralleled mounted, the changover relay allows :

connection of the ground power truck to its distribution busbar

connection of the AC generator to its distribution busbar

power supply to the faulty AC generators busbar

connection of the Auxiliary Power Unit (APU) to its main busbar

#71. Pulling the fire shutoff handle causes a number of devices to disconnect. In respect of the AC generator it can be said that the:

exciter control relay and the generator breaker open

generator breaker opens

exciter control relay opens

exciter control relay, the generator breaker and the tie breaker open

#72. As regards three-phase AC generators, the following conditions must be met for paralleling AC generators:1. Equal voltage2. Equal current3. Equal frequencies4. Same phase rotation5. Voltages of same phaseThe combination regrouping all the correct statements is :

1, 2, 3, 4

1, 4, 5

1, 3, 5

1, 3, 4, 5

#73. A magnetic circuit-breaker is:

is a system with a slow response time

can be reset without any danger even when fault remains

a protection system that has a quick tripping response

permits an overcurrent limited in time.

#74. When a persistent top excitation limit fault on an AC generator connected to the mains with another AC generator, the overexcitation protection device opens:

the tie breaker

the generator breaker

the exciter breaker, the generator breaker and the tie breaker

the exciter breaker and the generator breaker

#75. When a persistent overexcitation fault is detected on only one AC generator, the protection device opens the :

generator breaker and tie breaker

exciter breaker, generator breaker and tie breaker

tie breaker

exciter breaker and generator breaker

#76. When an underspeed fault is detected on an AC generator connected to the aircraft AC busbar, the protection device opens the:

generator breaker

exciter breaker

exciter breaker and generator breaker.

exciter breaker, generator breaker and tie breaker

#77. The services connected to a supply bus-bar are normally in:

series, so that isolation of loads increases the bus-bar voltage

series, so that isolating one load increases the bus-bar current consumption

parallel, so that isolating individual loads decreases the bus-bar current consumption

series, so that isolating one load increases the bus-bar current consumption

#78. To ensure correct load sharing between AC generators operating in parallel :

the matching of loads is unimportant

only real loads need to be matched

only reactive loads need to be matched.

both real an reactive loads must be matched

#79. When operating two AC generators unparalleled, the phase relationship of each generator:

must be in opposition

must be synchronous

must be 90° out of synchronisation.

is unimportant

#80. When AC generators are operated in paralllel, they must be of the same:

voltage and frequency

voltage and amperage.

frequency and amperage

amperage and kVAR

#81. Real load sharing in a parallel AC system is achieved by :

automatic adjustment of the torque on each generator rotor via the CSD unit

carefully selecting the number of loads on the bus-bars at any one time

controlling the generator field current

monitoring the kVAR of each generator/alternator

#82. Real load sharing in a parallel AC system is achieved by :

carefully secting the number of loads on the bus-bars at any one time

adjusting the torque on each generator rotor via the CSD unit

monitoring the kVAR of each generator/alternator

controlling the generator field current

#83. Load shedding means ..

Temporarily or permanent switching off of certain electric users to avoid overload of electric generators

Reduction of airloads on the flaps by means of the flap load relief value

A procedure used in control systems to reduce the stick forces

To leave behind extra cargo if the centre of gravity moves outside limits

#84. The speed of an asynchronous four-pole motor fed at a frequency of 400 Hertz is:

12000 revolutions per minute

1600 revolutions per minute

6000 revolutions per minute

800 revolutions per minute

#85. In an aeroplane utilising a constant frequency AC power supply, DC power is obtained from a :

Transformer Rectifier Unit

3 phase current transformer unit

static inverter

rotary converter

#86. On an aeroplane utilising AC as primary power supplies, the batteries are charged in flight from :

a Transformer Rectifier Unit

the AC bus via current limiters

a DC transformer and rectifier.

a static inverter

Finish