Electrical Flashcards
Electrical) What are the 3 main divisions of the Electrical System?
- AC Power System
- DC Power System
- Standby Power System
(Electrical) What are the two principles of the AC Electrical System?
- No paralleling of AC sources of power
* Source of power connected to a transfer bus automatically disconnects an existing source
(Electrical) With External Power available, how would you energize the Ground Service Busses?
By activating the Ground Service Switch on the Forward Attendant Panel.
(Electrical) What does an illuminated (Blue) GRD POWER AVAILABLE light indicate?
Ground Power is connected and meets the airplane power quality standards.
(Electrical) Moving the GRD PWR switch momentarily to ON does two things - what are they?
- Remove any previously connected power from the AC Transfer Busses and
- Connect Ground Power
(Electrical) What does the illuminated (Blue) APU GEN OFF BUS light indicate?
The APU is running, but the APU Generator in not powering a Bus
(Electrical) What does an illuminated DRIVE light on the Overhead Panel indicate?
IDG Low Oil Pressure or an Under Frequency condition (Caused by one of the following:
• IDG Failure
• Engine Shutdown
• IDG Automatic Disconnect due to High Oil Temperature
• IDG Disconnected through Generator Drive DISCONNECT switch
(Electrical) What does an illuminated (Blue) GEN BUS OFF light indicate?
That the respective IDG is not supplying power to it’s Transfer Bus
(Electrical) What does an illuminated SOURCE OFF light on the Overhead Panel indicate?
- No source has been manually selected to power the related Transfer Bus or
- The manually selected source has been disconnected
(Electrical) In addition to each AC Transfer Bus supplying power to a Main Bus, Galley Bus, and Service Bus what other bus is powered by AC Transfer Bus 1?
AC Standby Bus
(Electrical) What does an illuminated TRANSFER BUS OFF light on the Overhead Panel indicate?
The related Transfer Bus is not powered
(Electrical) When the BUS TRANS switch on the Overhead Panel is in AUTO (Guarded) and one of the sources powering a Transfer Bus is disconnected or fails what happens?
The source powering the opposite Transfer Bus automatically picks up the unpowered bus
(Electrical) What would moving the BUS TRANS Switch (Normally Guarded to Auto) to OFF accomplish?
Inhibit the automatic switching of Bus Tie Breakers (BTB’s)
(Electrical) How does automatic Load Shedding work?
- In Flight (if the APU is the ONLY source of Electrical Power, all Galley Busses and Main Busses are automatically shed)
- On Ground (if APU is the ONLY source of Electrical Power, it will attempt to carry a full electrical load. If an overload condition is sensed, the APU will start shedding Galley Busses and Main Busses until the load is within limits)
(Electrical) What does an illuminated TR UNIT light on the Overhead Panel indicate?
- In Flight (TR 1 has failed or TR2 AND TR3 have failed)
* On the Ground (any TR Unit has failed)
