section 7- electrical system Flashcards

1
Q

what currents make up the electrical system?

A

28v DC and 26/115v AC 400hz current

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2
Q

what currents make up the electrical system?

A

28v DC and 26/115v AC 400hz current

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3
Q

what is primary DC power supplied by?

A

2 engine driven starter generators and 2 nickel-cadmium batteries

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4
Q

what is used to provide 26/115V AC 400hz current?

A

2 static inverters

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5
Q

when will a non-essential bus relay disconnect the NON ESS BUS

A
  • If only battery power is available
  • double generator failure
  • NON ESS BUS B switch set to off
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6
Q

how is electrical power distributed?

A

from multiple buses through the main circuit breaker distribution box located on the overhead panels

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7
Q

where are the starter-generators mounted?

A

on the accessory gearbox of each engine

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8
Q

what does the starter-generator act as during engine start?

A

a direct driven starter

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9
Q

what does the starter-generator act as during engine operation?

A

a DC generator

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10
Q

what is the starter-generators nominal output?

A

28V DC at 250 amperes each

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11
Q

following engine start when will the generator deliver electrical power?

A

when the respective GEN switch is set to on

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12
Q

what protects the generators?

A
  • GEN RESET LH/ESS BUS on the overhead breaker panel

- GEN RESET RH/ESS BUS on the overhead breaker panel

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13
Q

what is primary DC power supplied by?

A

2 engine driven starter generators and 2 nickel-cadmium batteries

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14
Q

what is used to provide 26/115V AC 400hz current?

A

2 static inverters

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15
Q

when will a non-essential bus relay disconnect the NON ESS BUS

A
  • If only battery power is available
  • double generator failure
  • NON ESS BUS B switch set to off
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16
Q

how is electrical power distributed?

A

from multiple buses through the main circuit breaker distribution box located on the overhead panels

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17
Q

where are the starter-generators mounted?

A

on the accessory gearbox of each engine

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18
Q

what does the starter-generator act as during engine start?

A

a direct driven starter

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19
Q

what does the starter-generator act as during engine operation?

A

a DC generator

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20
Q

what is the starter-generators nominal output?

A

28V DC at 250 amperes each

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21
Q

following engine start when will the generator deliver electrical power?

A

when the respective GEN switch is set to on

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22
Q

what protects the generators?

A
  • GEN RESET LH/ESS BUS on the overhead breaker panel

- GEN RESET RH/ESS BUS on the overhead breaker panel

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23
Q

what batteries are installed?

A

either:

2x 24v 25 ampere hour nickel cadmium batteries

2x 24v 27 ampere-hour nickel cadmium batteries

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24
Q

where are the batteries installed?

A

either in the nose section or the LH wheel well

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25
what are both batteries normally connected to?
Bus 1
26
if Bus 1 fails what can the batteries be switched to?
Bus 2
27
when does the battery supply power to the electrical system?
when either the battery or master switch is set to ON
28
what are the batteries protected by?
- BUS 1/HOT BUS - BUS 2/HOT BUS - TIE/HOT BUS - GEN/BATT/HOT BUS - BATT 2/HOT BUS - GEN/BATT/HOT BUS
29
Where is the external DC receptacle installed?
front fuselage
30
what must maximum output of the external power unit not exceed?
1000 amps at 28v
31
when will the white EXT power light illuminate?
when the external power unit is connected
32
when does the GPU supply power to the electrical system?
when both BATT switches are set to EXT and the master switch is ON
33
where may the 28v receptacle be installed in the cabin?
rear part of the cabin
34
what will protect the 28v receptacle in the cabin if installed?
RECEPTACLE TEST/NON ESS BUS on the LH avionics rack breaker panel
35
what does the AC electrical system employ?
2 350 VA static inverters which are powered through BUS 1 and 2.
36
what does each static inverter in the AC electrical system provide?
26/115V AC 400hz current to its own bus system.
37
what happens if one of the static inverters in the AC electrical system becomes inoperative?
the load will be automatically transferred to the other
38
what protects the AC electrical system?
- INV 1/BUS 1 on the overhead breaker panel | - INV 2/BUS 2 on the AC/DC breaker panel
39
where is the master switch located?
RH overhead switch panel
40
what does the MASTER switch do in the ON position?
connects all electrical power to sources to the buses
41
what is the main function of the MASTER switch?
to disconnect the electrical buses from the electrical power source in case of emergency
42
when can we not reset the master switch to ON?
with one or both generator switches in the ON position
43
what must we do with the BATT switches before Turning the MASTER switch on?
set them the desired position (ON or EXT)
44
where are the 2 BATT switches located?
RH overhead switchpanel
45
what if the BATT switch is set to the ON position?
the battery is connected to the DC electrical buses. external power will be disconnected
46
what if the BATT switch is set to the OFF position?
the battery relay is de energised, disconnecting all electrical buses, including external power
47
what if the BATT switch is set to the EXT position?
external power is supplied to the electrical buses if connected
48
what must be in the EXT position to have external power?
both BATT switches
49
where is the 3 position TIE switch located?
RH overhead switch panel
50
what if the TIE switch is in the TIE (centre) position?
both BUS 1 and BUS 2 are connected both batteries are charged by GEN 1 and 2
51
what if the TIE switch is set to BATT BUS 1 (left)
BUS 1 AND 2 are separated GEN LH powers BUS 1 and GEN RH powers BUS 2 both batteries are connected to BUS 1
52
what if the TIE switch is set to BATT BUS 2 (right)
BUS 1 and 2 are separated GEN LH powers BUS 1 and GEN RH powers BUS 2 both batteries are connected to BUS 2
53
what will happen on G-SAYE when GPU power is applied?
the TIE switch is disabled, the bus tie relay is closed
54
what will happen on all aircraft except G-SAYE when the GPU is connected?
in position TIE: BUS 1 and BUS 2 are connected BUS 1 and 2 are connected to the GPU in position BATT BUS 1: BUS 1 and 2 are separated BUS 1 is connected to the GPU BUS 2 is isolated from the GPU in position BATT BUS 2: BUS 1 and 2 are separated BUS 1 is isolated from the GPU BUS 2 is connected to the GPU
55
Where are the 2 generator switches located and what are they labelled?
RH overhead switch panel - GEN LH - GEN RH
56
what does the generator switch ON position do?
connects the generator to the electrical system through a relay and voltage regulator
57
what will de energise the generator field relay to disconnect the generator from the system?
overvoltage or undervoltage
58
what needs to take place before reconnecting the generator to the system after and over voltage/undervoltage condition?
the applicable generator switch must be held at reset for 5 seconds to restore generator field circuit and then to on- check for normal voltage indications before switching on.
59
where is the guarded NON ESS-B switch located?
RH overhead switch panel
60
what is the NON ESS B switch for?
disconnecting the NON-ESSENTIAL BUS to reduce the load from the power source if only limited electrical power is available
61
what powers the NON-ESS BUS switch?
28v DC
62
what protects the NON ESS BUS switch?
- NON ESS BUS/ESS BUS on the overhead breaker panel
63
where is the voltmeter selector switch located?
RH overhead switch panel
64
what is the voltmeter selector switch used for?
checking the voltage of the ESS BUS when the switch is in the centre position or the output of the selected generator if switched to GEN LH/RH position
65
where is the DC voltmeter located?
RH overhead switch panel above the voltmeter selector switch, graduated from 0-32 volts.
66
what is the green range on the DC voltmeter?
26-28.5 volts
67
where is the DC ammeter for each generator located?
RH overhead switch panel, graduated from 0-500 amperes
68
what does the DC ammeter indicate?
electrical load of the generator
69
what is the green range on the DC ammeter?
0-250 amperes
70
what is the yellow range on the DC ammeter?
250-500 amperes
71
where are the 2 inverter switches located?
RH overhead switch panel and labeled ON, OFF, RESET
72
what are the 2 AC voltmeters on the RH overhead panel labeled?
INV 1 and INV 2
73
what range do the AC voltmeters show?
0-130V
74
what are the ac voltmeters used to measure?
inverter output
75
what is the green range of the AC voltmeters?
110-120v
76
what does the engine and battery pre-heater system do if installed?
assists in starting the engines in cold climates and reduces engine wear and the adverse effects of thermal shock normally associated with cold starts
77
how long do the engine and battery pre heaters need to preheat the engine to 55C after a cold soaking?
5-6 hours
78
what protects the engine and battery pre-heater system?
circuit breakers and earth leakage trip switches all located in the LH battery compartment
79
what supplies the battery and engine pre-heater system?
115v AC or 220v AC
80
what circuit breakers need to be IN before connecting the preheater?
1-4HD
81
what needs to be off before connecting the pre-heater?
13-14hd leakage trip switchs