737 Electrical System And Lighting

Front 1

4 sources of AC power?

Back 1

2 engine driven generators, AC external, APU generator

Front 2

GRD POWER AVAILABLE blue light means?

Back 2

External power is available (no info on quality). Stays on while in use. *External AC bus is powered*

Front 3

What is the caution regarding the EXTERNAL POWER CONN light?

Back 3

If it's on and EXTERNAL POWER NOT IN USE is out, do not disconnect external power.

Front 4

BPP is?

Back 4

Bus Protection Panel. Tastes external power for you and allows both Ground Power Relays (GPR) to close if it's good.

Front 5

When is Galley Power shed?

Back 5

During single generator operation

Front 6

Ground Service Switch. Where is it, what does it power, and where does it get power from? When does it automatically switch off?

Back 6

FWD FA panel. Connects external power directly to ground service bus only (utility outlets, battery charger, cabin lighting). Electromagnetically held in on, auto off if EXT PWR lost or generator bus 1 is powered.

Front 7

Generator and Main Busses provide power for what kind of systems?

Back 7

non essential items (galley power and cabin lighting) and high-load items (electric hyd pumps and window heat)

Front 8

Transfer busses power?

Back 8

Main instrument controls, displays, and some essential items (eg, EHSI, EADI, FMC, CDUs, engine ignition, anti smash lts)

Front 9

When a generator is lost, where does the transfer bus get its power from?

Back 9

Offside Generator Bus

Front 10

Battery charger normal power source? Transfer power source?

Back 10

Generator bus 1 transfers to main bus 2

Front 11

T/R 1 powers:
T/R 2:
T/R 3:

Back 11

DC bus 1
DC bus 2
Battery Bus

Front 12

what happens in the event of a TR failure

Back 12

Other two take over, except in case of TR 3. In this case battery bus goes to the hot battery bus.

Front 13

Purpose of the battery

Back 13

APU start and emergency power for essential equipment.

Front 14

Loss of both generators, battery supplies power (30 min) to which 5 buses?

Back 14

-Hot Battery Bus
-Switched Hot Battery Bus
-Battery Bus
-AC standby bus
-DC standby bus

Front 15

What 3 conditions are needed for an automatic transfer of both standby busses occur?

Back 15

STANDBY POWER switch is in AUTO, the airplane is airborne, and EITHER transfer bus 1 OR DC bus 1 loses power.

Front 16

Manually positioning the STANDBY POWER switch to BAT does what?

Back 16

AC standby bus, DC standby bus and battery bus switch from primary power source to secondary power source.

Front 17

Primary and secondary power sources for AC standby bus, DC standby bus, and battery bus?

Back 17

AC: transfer bus 1; battery bus thru static inverter
DC: DC bus 1; battery bus
Battery bus: TR3 ; hot battery bus

Front 18

STANDBY POWER to OFF does what?

Back 18

Disconnects power from AC and DC standby busses, regardless of primary power source availability. Does not affect Battery Bus.

Front 19

When does amber STANDBY PWR OFF light illuminate?

Back 19

When AC standby bus is not powered (light doesn't monitor DC standby bus).

Front 20

STANDBY POWER switch does not affect which bus?

Back 20

Switched Hot Battery Bus

Front 21

Two sources for battery charger?

Back 21

Primary: GND service bus via generator bus 1
Secondary: Main bus 2 via generator bus 2

Front 22

What will happen if you push RESID VOLTS button with generator control breaker and generator field relay closed?

Back 22

The airplane blows up. No, not really. But you can damage AC voltmeter.

Front 23

GFC open what indications show on CPS FREQ meter and AC VOLTS meter?

Back 23

Needles pegged to left. Can check residual voltage in this configuration.

Front 24

BAT switch ON and OFF, what are the power sources for the switched HBB and the BB?

Back 24

ON: switched hot battery bus powered by the battery charger, the battery, or DC ext. Battery bus powered by TR3 or hot battery bus
OFF: removes DC power from switched hot battery bus and battery bus.

Front 25

BAT switch OFF and STANDBY POWER switch to BAT?

Back 25

Battery bus gets power from hot battery bus, but switched hot battery bus remains unpowered.

Front 26

When do flourescent background lights illuminated at a fixed intensity?

Back 26

Loss of transfer bus 1 (now powered by AC standby bus)

Front 27

What lights are NOT tested by Master lights switch? (3-4)

Back 27

-marker beacon
-autoflight annunciator (A/P, A/T, FMC)
-parking brake
-(on some airplanes) master fire warning lights

Front 28

FASTEN BELTS switch AUTO

Back 28

illuminates when gear is down or TEF not up...

Front 29

Power SOURCE for T/R 1:

T/R 2:

T/R 3:

Back 29

-Transfer bus 1
-Transfer bus 2
-Main Bus 2

Front 30

What happens if BUS TRANSFER switch is placed to OFF?

Back 30

Automatic transfer of power cannot occur. Used to provide isolation of two sides in event of electrical malfunction.

Front 31

Where do each of the three T/R's get their AC power?

Back 31

1: Transfer bus 1
2: Transfer bus 2
3: Main bus 2

Front 32

Explain operation of DC tie-bus.

Back 32

When open, isolates T/R1 from T/R 2 and3.

Front 33

When is the DC tie-bus open?

Back 33

BUS TRANSFER switch to off, or automatically when glideslope capture w/at least 1 FD or 1 AP engaged in CMD. For cat II/III cert.

Front 34

24VDC battery range?

Back 34

22-30 Volts

Front 35

Describe battery charging.

Back 35

After usage the DC ammeter shows a high charge rate. At approx 16 amps, goes to a 2 minute pulse cycle. Ammeter at zero indicates fully charged battery.

Front 36

Does battery charge during APU start?

Back 36

No, automatically disconnected by APU start battery charger cutout relay to prevent charger overheat.

Front 37

Some things lost with Generator 1?

Back 37

-Landing Light Combo
-Windshield Heat Combo
-2 fuel pumps (onside Fwd, ctr offside)
-L elev pitot heat
-offside elect pump
-equipment cooling

Front 38

Some things lost with generator 2?

Back 38

Same as 1
T/R 3
Recirc fan
Engine Vib monitor (non EIS)
Equipment cooling Alternate

Front 39

What three things does the BUS TRANSFER switch in OFF do?

Back 39

-prevents operation of transfer relays
-Opens DC disconnect relay
-Prevents battery charger from switching to secondary power source.

Front 40

What does Break before Make mean?

Back 40

AC, existing power source is always disconnected automatically before the oncoming power source is connected.

Front 41

You have both generator busses powered by the APU on the ground. You forget, and takeoff this way. What will happen?

Back 41

Nothing. It's designed to only power one in flight, but it won't drop one automatically if you takeoff with both on the APU. You have to take one off manually.

Front 42

How does the APU generator maintain a constant operating speed?

Back 42

No CSD, fuel controller on APU does it.

Front 43

What does the GCU do?

Back 43

Does not allow a generator to be connected to the electrical system unless the generator output voltage and frequency are within preset limits.

Front 44

T/R 3 powered by and gives power to?

Back 44

Powered by Main Bus 2 and supplies primary DC power to the battery bus.

Front 45

What is the power source for the Fuel Crossfeed Valve and Light?

Back 45

Hot Battery Bus

Front 46

What does the RESID VOLTS Button do?

Back 46

Allows AC VOLTS meter to display residual voltage of the selected generator. If the generator drive is disconnected, the residual voltage indicates near zero

Front 47

What does T/R 1 position of the DC Meter Selector do?

Back 47

Displays DC amperage load of T/R 1 and DC voltage of DC bus 1.

Front 48

Momentary actuation of either DISCONNECT switch results in what?

Back 48

Generator disconnect wheter or not the engine is running. Reset can only be accomplished on the ground.

Front 49

RISE Scale shows what?

Back 49

Temperature difference of the generator drive oil input and output ports. A high temperature rise indicates excessive generator workload.

Front 50

IN scale shows what?

Back 50

Generator drive oil input. A high temperature indicates inefficient generator drive cooling, usually accompanied by low rise temp and a HIGH OIL TEMP light.

Front 51

When does the FASTEN BELTS switch in the AUTO position illuminate the FASTEN BELTS signs?

Back 51

Landing Gear Lever DN
or
Flap Lever out of UP

Front 52

What is the airspeed restriction on the outboard landing lights?

Back 52

None. Nada. Zip. Extend or retract them any time you want Mav.

Front 53

What happens if the Taxi Light is left on and the gear is raised?

Back 53

Nothing. It burns away with the intensity of a billion white hot suns.

Front 54

What is special about the left dome light bulb?

Back 54

It is not controlled by the DOME WHITE switch, it operates as part of the emergency exit light system.