Chapter 6: Electrical Flashcards Preview

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Flashcards in Chapter 6: Electrical Deck (22)
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1
Q

Describe the function of the GROUND SERVICE switch on the Forward F/A panel.

A

Provides manual control of ground service busses. Enables servicing of airplane using external power without activating AC transfer busses.
ON – connects external power to ground service bus.
OFF – disconnects external power from ground service bus.

2
Q

Explain the meaning of the blue GRD POWER AVAILABLE light.

A

Illuminated (blue)- Ground power is connected and meets airplane power quality standards.

3
Q

Explain the meaning of the blue APU GEN OFF BUS light.

A

Illuminated (blue)-APU is running and not powering a bus.

4
Q

Explain the meaning of the blue GEN OFF BUS light.

A

Illuminated (blue)-IDG is not supplying power to the related transfer bus.

5
Q

Recall where to read voltage, frequency and amps.

A

AC and DC Metering panel on the Forward Overhead panel.

6
Q

Explain the meaning of the amber DRIVE light.

A

Illuminated (amber)-Integrated Drive Generator (IDG) low oil pressure.

7
Q

Explain the meaning of the amber TRANSFER BUS OFF light.

A

Illuminated (amber)-
- Related Transfer Bus is not powered.
Extinguished-
-Related Transfer Bus is powered

8
Q

Explain the meaning of the amber SOURCE OFF light.

A

Illuminated (amber)-
No source has been manually selected to power the related transfer bus, or the manually selected source has been disconnected.

Note: SOURCE OFF light triggers ELEC light and Master Caution to alert crew of change to source of power to associated Transfer Bus.

9
Q

Explain the meaning of the amber BAT DISCHARGE light.

A

Illuminated (amber)-

With BAT switch ON, excessive battery discharge detected.

10
Q

Explain the meaning of the amber TR UNIT light.

A

Illuminated (amber) – TR failure.

11
Q

Explain the meaning of the amber ELEC light.

A

Illuminated (amber)-
fault exists in DC power system or standby power system.
Note: Operates only with airplane on ground.

12
Q

Explain the meaning of the amber STANDBY PWR OFF light.

A

Illuminated (amber)-One or more of the following busses are unpowered:

  • AC standby bus.
  • DC standby bus.
  • Battery bus.
13
Q

Recall the number of minutes available on standby power with two fully
charged batteries.

A

-60 minutes.

14
Q

Recall the function of the Ground Power (GRD PWR) switch.

A

Three position switch, spring loaded to neutral
OFF – disconnects ground power from AC transfer busses.
ON – if momentarily moved to ON position and ground power is available:
-removes previously connected power from AC transfer busses.
-connects ground power to AC transfer busses when power quality is correct.

15
Q

Recall that it is not possible to use APU power and GRD power at the same time.

A

There are two basic principles of operation for the 737 electrical system:

  • No paralleling of AC sources of power.
  • The source of power being connected to a transfer bus automatically disconnects the existing source.
16
Q

Recall the function of positioning the APU Generator (GEN) Switches to ON.

A

Neither AC transfer bus powered by an IDG
Moving an APU GEN switch to ON:
- Powers both AC transfer busses from the APU generator.
- Disconnects external power, if connected.
-opposite SOURCE OFF light illuminates Until the APU GEN switch is moved ON.Both AC transfer busses powered by IDGs Moving an APU GEN switch to ON:
- - Powers the related AC transfer bus from the APU generator.
- Other AC transfer bus continues to receive power from the IDG.

17
Q

Recall the components powered by the ground service bus.

A
  • Utility outlets.
  • Cabin lighting.
  • Battery chargers.
18
Q

Recall the location of the GROUND SERVICE Switch

A

The forward flight attendant control panel.

19
Q

Recall the function of the Generator (GEN) Switches

A

Three position switch spring-loaded to neutral
OFF – disconnects IDG from related AC transfer bus by opening generator circuit breaker.
ON – connects IDG to related AC transfer bus by disconnecting previous power source and closing generator circuit breaker.

20
Q

Recall the function of the BUS TRANSFER Switch.

A

AUTO (guarded position) – bus tie breakers operate automatically to maintain power to AC transfer busses from any operating generator or external power.
OFF – isolates AC transfer bus 1 from AC transfer bus 2.

21
Q

Recall the function of the Generator Drive Disconnect (DISCONNECT) Switches. (guarded)

A

Disconnects IDG if electrical power is available and engine start lever is in IDLE. IDG cannot be reconnected in the air.

22
Q

Explain the function of the BAT (battery) switch.

A

ON –

  • Provides battery power.
  • Provides automatic switching of standby electrical system to battery power with loss of normal power.

OFF –
-Removes battery power.