Block 3: Avionics/Electrical-G. Elictrical Components Flashcards
What makes up the electrical power supply system?
Two generators, two transformer-rectifiers (TR), one battery with dedicated battery charger, and a power distribution (BUS) system.
What is the function of the generator?
Each one provides a primary ac source and three isolated dc sources from a permanent magnet generator (PMG). During normal operation, the left generator powers only the left buses while the right generator powers only the right buses. If one generator fails, the other generator is capable of carrying the entire electrical load of the aircraft.
What is the main function of the battery?
It’s provided for normal engine start. External electrical power can be applied to power the entire system of the ground.
What is the function of the bus system?
It consist’s of the left and right 115 vac buses, right 26 vac bus, left and right 28 vdc buses, 28 vdc essential bus and a 28 vdc maintenance bus.
What is the function of the maintenance battery?
It supplies 28 vdc power to the essential and maintenance buses. The battery supplies power to the essential busses if both power supplies and both AC generators are inoperative. The battery supplies power for engine start when external power is not applied.
What is the function of the emergency battery (E-BATT), F/A18A-D.
It’s used for engine start when external power or aircraft generator power is not available, and are used to power the essential 24/28 volt dc bus when both transformer-rectifiers are lost. The EBATT powers the maintenance 24/28 volt dc bus when both transformer-rectifiers are inoperative. It allows operation of the canopy and maintenance monitor on the ground without any other electrical power on the aircraft. The contractor will automatically close in response to a low voltage condition from the U-BATT.
Define the two generators?
Each of them is a variable speed constant frequency power generator system supplying 115/200 vdc, 400 Hz, three phase electrical power; also supplies 28 vdc power. The presence of an under-speed, over voltage, under-voltage, over-frequency, under-frequency, feeder fault, excessive waveform distortion or excessive dc voltage content causes the generator to de-energize the power contractor and the system output is disconnected from the main ac bus and must be reset.
