加拿習(xí)加國學(xué)習(xí)aes comm4

1、Section 4.6 Electrical SystemLesson ObjectivesGenerator / Alternator / BatteryLightingMaster / Alternator / Generator SwitchesAmmeter / Load MeterBus BarsCircuit Breakers / FusesGrounding / BondingGenerator / Alternator / BatteryThe generator supplies direct current to the electrical system.Its purp

2、ose is to supply current and to recharge the battery.It is driven by the engine. ( some really old airplanes had a wind driven fan that turned the generator)The generator is somewhat heavy and inefficient compared to its modern replacement the alternator. AlternatorThe alternator supplies electric p

3、ower to the electrical system. It works on a different principle and generates AC (alternating current) internally and then the current is rectified by diodes to give DC ( direct current).The alternator is more efficient through a range of engine speeds and takes less horsepower to turn. Alternators

4、 often weigh less than a comparable generator.BatteryThe battery stores the electrical energy required to operate various instruments and equipment.It is important that the battery be fully charged to insure that the electrical components run satisfactorily.Light aircraft batteries are considerably

5、smaller than automobile batteries, so they must be handled with caution and respect.LightingTwo divisions here; exterior and interior lighting.Exterior LightingConventional navigation lights located on the wing tips and the top of the rudder.A single landing light or dual landing/taxi lights also ar

6、e included.A flashing beacon is required and this lighting package may be supplemented by strobe lights.Interior LightingInstrument and control panel lighting provided by flood lighting and post lights.It used to be believed that red light helps with night vision but actually its one of the worst co

7、lors of light to use. (More in Human Factors)Engine instruments, radio equipment , and the magnetic compass frequently have their own internal lighting.Master/Alternator/Generator SwitchesOften the master switch is a split rocker type switch labelled MASTER.The right half of the switch, labelled BAT

8、, controls all electrical power to the aircraft.The left half, labelled ALT, controls the alternator.Normally, both sides of the master are used simultaneously; however the BAT side may be turned on to check electrical equipment on the ground.Ammeter / Load MeterThe ammeter indicates the flow of cur

9、rent, in amperes, from the alternator to the battery, or from the battery to the a/c electrical system.When the engine is operating and the master is turned on, the ammeter indicates the charging rate applied to the battery.Some airplanes are equipped with an automatic over voltage protection system

10、 consisting of an over voltage sensor behind the instrument panel and a red warning light. Bus BarsThe bus bar is a large conductive metal strap to which various electrical terminals are attached. It can be thought of as similar to the service panel in your home.The bus bar receives current produced

11、 by the alternator and the battery.From the bus bar current goes to various circuit breakers and to various electrical circuits connected to electrical components.Circuit Breakers / FusesAll electrical circuits are protected by circuit breakers or fuses.These are part of the system to protect the co

12、mponents and the wiring against damage caused by short circuits and excess current.Most circuit breakers are the “ push to reset” type, but some a/c are equipped with a toggle type circuit breaker to protect the avionics package.Grounding / BondingGrounding is a method of providing electrical curren

13、t paths through the airframe.The negative side of the battery terminal connects to “ground” which provides the complete path for various electrical circuits through the airframe“Single wire construction”Grounding / BondingVarious fixed and moveable components of the aircraft are provide with (flexib

14、le) electrical straps or wires so that the entire airframe is interconnected. The electrical system is “bonded” together.This helps prevent dissimilar charges and electrical “noise” which can affect navaids and radios.Grounding / BondingBecause the aircraft flies through the air, it can at times bui

15、ld up a considerable static electrical charge.To help prevent this, static discharge wicks are installed at strategic locations on the airframe to help dissipate any static electric charge.Grounding / BondingBecause the static charge can be high on occasion, it is imperative that when an aircraft is refueled, it is first connected to ground to dissipate any static chargeThe action of fueling itself may also build up an electrical char