lOMoARcPSD|20184608

41. In multi-engine aircraft, If ground power sources include external power and APU
generator, these ground power sources:
A. cannot be switched in parallel
B. can be switched in parallel if one main generator fails
C. can be switched in parallel
42. Which of the followings are considered distribution failures?
A. Overload; Open phase; Short-circuit
B. Over/under-voltage; over/under-frequency; underspeed
C. Underspeed, Differential protection
43. Electrical power in aircraft is mainly used for:
A. Lighting (cockpit, cabin, exterior); Electronic devices (computers, controls, indications,
sensors). Heating needs hot air only
B. Heating (galley, anti-icing); Lighting (cockpit, cabin, exterior); Electronic devices
(computers, controls, indications, sensors). Pumps and valves needs hydraulic power
C. Heating (galley, anti-icing); Lighting (cockpit, cabin, exterior); Mechanical power
(pumps, valves, motion); Electronic devices (computers, controls, indications, sensors)
44. AC power is generated using by
A. a constant speed generator or VSCF
B. a constant speed generator
C. a constant speed generator or a static inverter or VSCF
D. a static inverter
45. The emergency generator supplies 115 V AC directly to
A. AC Essential buses
B. AC Essential and Emergency Busses
C. AC main buses
46. In three-phase generator, voltage measured from one phase to another phase is
A. 320V
B. 115V
C. 200V
47. Which statement is NOT true for AC power sources used in modern jet aircraft?
A. They provide 115V, 400HZ, 3 phase power
B. They provide about 95% of the total electrical energy
C. Normal AC power sources provide DC power via TRUs
48. At terminal block of a generator installed in modern aircraft, there are:
A. 3 cables
B. 4 cables
C. 5 cables
49. Output frequency of engine drive generator stays within 400Hz thanks to:
A. Constant Speed Drive (CSD) via control signal from GCU
B. Exciter current via control signal from GCU
C. CBMU
50. How many power sources are used for AC generation in modern aircraft?
A. 06
B. 04
C. 05
D. 03

Downloaded by Nguyen Sy Tan (sytan2004@gmail.com)

 lOMoARcPSD|20184608

51. Essential power distribution consists of

A. Both AC and DC power
B. DC power
C. AC power
52. Main components for electrical distribution are:
A. Power relays, circuit breakers and fuses
B. Power relays used as switching devices; circuit breakers and fuses as safety devices and
current transformers as measuring devices
C. Power relays used as safety devices; circuit breakers and fuses as switching devices and
current transformers as measuring devices
53. For twin engine aircraft, if DC bus 1 fails, DC ESS bus is supplied by:
A. ESS TR
B. TR1
C. TR2
54. In case of total loss of the normal power sources, emergency power distribution is
switched to
A. Emergency generator (higher priority) or Batteries
B. APU
C. Emergency Generator
D. Batteries
55. When both APU and external power are available, the Aircraft will use
A. Both APU and External power
B. APU
C. External power
56. GCU power supply is from:
A. Normal power: PMG; Backup power: Battery
B. Normal power: DC bus 1; Backup power: DC ESS bus
C. Normal power: AC bus 1; Backup power: AC ESS bus
57. The function of NBPT (No Break Power Transfer) is
A. prevent the overload
B. Prevent the short circuit
C. Prevent a loss of power when power source switching
58. The function of VSCF:
A. Protection in during flight
B. Generate the 3 phase AC with constant frequency with variable speed input.
C. Frequency regulation
D. Vogtage regulator
59. The function of TR units is
A. Convert 115V AC to 24 V AC
B. Convert 115V three phases to 28V DC
C. Convert 24V Dc to 115 V AC
60. Cooling methods affect the performance of generators such as load limit. Which
generators have a higher load limit, oil-cooled generators or air-cooled ones?
A. Air-cooled generators
B. Oil-cooled generators
C. Oil-cooled or air-cooled generators have the same load limit

Downloaded by Nguyen Sy Tan (sytan2004@gmail.com)

 lOMoARcPSD|20184608

61. The light “AVAIL” in the cockpit illuminates when the quality of external power is
good. These lights are supplied by:
A. Aircraft battery
B. The external power via a TR inside the GPCU
C. A battery inside GPCU
62. The battery charger controls the charging current by two methods: constant
current and constant voltage. When a battery is fully charged, which charging method is
used?
A. Constant current: to make a quick and safe charge
B. Constant current: to prevent battery overheat
C. Constant voltage: to compensate for battery self-discharge and to prevent overcharge
63. In twin engine aircraft, Engine 1 and APU running, when you connect external
power, which unit checks whether power is ready or not?
A. GPCU (Ground Power Control Unit) only
B. GCU (Generator Control Unit) and GPCU (Ground Power Control Unit)
C. APU GCU and GCU
64. Which of the following failures triggers automatic trip function without a time
delay?
A. Open phase
B. Shorted circuit
C. Overvoltage
65. Electrical power supplying all systems to operate the aircraft safely is called
Essential Power. Essential power supplies:
A. Captain’s navigation, communication equipment
B. Captain’s navigation, communication equipment, important control and warning systems
C. Captain and First officer’s navigation and communication equipment
66. If the current of TR unit drops below about 2 Ampere:
A. TR unit is switched off and can be swtiched by a reset signal, during the flight.
B. TR unit is switched off, the warning message is in ECAM system page
C. TR unit is only switched off manually by the coressponding button by the electrical
67. What does happen when you open the secondary winding of a current transformer
during normal operation?
A. The current transformer will be decreased
B. the current transformer will be damaged
C. The current transformer will be increased
68. What will happen if overvoltage failure occurs?
A. The alarm “system failure” and GCR automatically trips
B. The engine will be shutdown to protect the electrical system
C. The alarm “system failure”, and GCR and GPR automatically trip
69. In isolated operation, Main DC Power switching relay:
A. Normally open and close if TR1 or TR2 is shorted
B. Normally close and open if TR1 or TR2 fails
C. Normally open and close if TR1 or TR2 fails
70. When overload is detected, the protection circuit will automatically:
A. Open GCR (Generator Control Relay)
B. Switch off large loads such as galleys

Downloaded by Nguyen Sy Tan (sytan2004@gmail.com)

 lOMoARcPSD|20184608

C. Open GPR (Generator Power Relay)

71. Which of the following is the most probable reason for the under-speed conditions?
A. Engine shutdown or engine start not completed
B. Faulty in generator windings
C. Faulty GCU
72. In three-phase generator, the voltage measured from one phase to neutral is
A. 300 V
B. 115V
C. 200V
73. A generator has two polepairs, if it generates a power with 400 Hz, the input speed
is:
A. 8000 RPM
B. 6000 RPM
C. 1200 RPM
D. 2400 RPM
74. When two IDGs in twin engine aircraft fails, AC EMER bus is supplied by:
A. Static inverter only
B. EMER GEN or static inverter as the last power source
C. EMER GEN only
75. How much power can external power produce?
A. 5 KW
B. 60 KW to 90 KW
C. 65 KW
D. 1 KW
76. Are two external power sources switched in parallel?
A. Yes, because they are the same parameters.
B. No, because ground power sources cannot be synchronized
C. Yes, because ground power sources can be synchronized
77. No Break Power Transfer (NBPT) requires synchronization of:
A. Voltage, Frequency and phase angle
B. Voltage and Frequency
C. Voltage only
78. In during the flight, The emergency power switching is
A. normally automatic but Pilot can active by the corresponding button.
B. only automatic
C. only manual
79. For twin engine aircraft, If AC bus 1 is shorted,
A. AC ESS bus is no longer powered
B. AC ESS bus is powered AC bus 2
C. AC ESS bus is powered by static inverter or EMER GEN
80. Aircraft battery is used to supply:
A. the emergency power & the APU starter motor
B. normal DC buses & the APU starter motor
C. APU starter motor and Emergency Generator stater
81. A Battery Charge Limiter (BCL) is designed to:
A. Monitor (1) and Monitor (2)

Downloaded by Nguyen Sy Tan (sytan2004@gmail.com)

 lOMoARcPSD|20184608

B. Monitor (2): battery voltage drop (below 23V) during discharge in flight
C. Monitor (1): charge current to prevent risk of thermal runway
82. When aircraft is energized by APU, if you disconnect APU GCU, what might
happen?
A. APU GCU is damaged
B. Nothing happens
C. Current transformer connected to APU GCU is damaged
83. GCU detects an over-frequency when the frequency measured at the PMG exceeds
430Hz and under-frequency when it drops below 370Hz. If under-speed condition
presents, the automatic trip is inhibited in which case, over-frequency or under-
frequency?
A. Under-frequency only
B. Over-frequency only
C. Both over-frequency and under-frequency
84. The function of Load shedding is
A. Improves the reliability of the power relays
B. Increase loads when operating parrallel.
C. Improves the reliability of the power relays and Prevents an overload of the power
D. Prevents an overload of the power
85. Which of the following are considered AC generation failures?
A. Overload; Open phase; Short-circuit
B. Over/under-voltage; over/under-frequency; underspeed
C. Underspeed, Differential protection
86. In parallel operation, if the difference between average current of all generator and
current of generator 1 exceeds 50A, what will happen with bus tie switch for AC bus 1?
A. Bus tie for AC bus 1 will close to isolate the AC bus 1, the failure of Gen 1 will be
detected by protection circuits and will be shutdown, AC bus 1 will no be supplied
power.
B. Bus tie for AC bus 1 will open to isolate the AC bus 1, the failure of Gen 1 will be
detected by protection circuits and will be shutdown, AC bus 1 will no be supplied
power.
C. Bus tie for AC bus 1 will open to isolate the AC bus 1, Gen 1 will be shutdown, this bus
tie will close again.
87. In parallel operation (multiengine aircraft), if the different phase of a line of
generator 1 and a live bus in AC distribution is 180 degrees, the different voltage between
two lines is
A. 320 V
B. 0 V
C. 115V
D. 230 V
88. In towing of the aircraft, a towing bus will be supplied by
A. Main AC power distribution
B. Towing static inverter
C. external power
89. DC power sources are:
A. APU and Batteries

Downloaded by Nguyen Sy Tan (sytan2004@gmail.com)