Chapter 7 Aircraft Control Circuitry

航空发表于 2011-9-20 08:20:06

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航空发表于 2011-9-20 08:21:00

Chapter 7 Aircraft Control Circuitry POWER CIRCUITS Figure 7-1. Battery Circuit A clipping diode is installed across the coil of the solenoid to eliminate spikes of voltage that are induced when the master switch is opened and the magnetic field from the coil collapses. The resulting spikes of voltage from a solenoid or relay coil may cause damage to sensitive electronic components if they are not controlled by a clipping diode. The diode simply isolates, or blocks, the induced voltage from flowing into the bus side of the electrical system, thereby protecting the electronic components from the high voltage. Figure 7-1 Battery Circuit Most aircraft have some components that require power all the time, whether the master switch is on or not. These low-current items, such as clocks and flight-hour meters, are connected to the main terminal of the battery solenoid, and supply current to these components anytime a charged battery is installed in the aircraft. These circuits often employ a fuse to protect the circuit. GENERATOR CIRCUIT Figure 7-2. Ammeter monitoring circuit 0 10 20 30 AMMETER ALTERNATOR BATTERY BUS 0 10 20 30 AMMETER ALTERNATOR BATTERY BUS TO AIRCRAFT LOADS TO AIRCRAFT LOADS AMMETER INSTALLED IN ALTERNATOR OUTPUT LEAD (A) AMMETER INSTALLED IN THE BATTERY LEAD (B) Figure 7-4. A basic generator circuit B G F F A+ G MAI N B US VOLTAGE REGULATOR MASTER SWITCH GENERATOR BATTERY CONTACTOR Figure 7-5. The internal circuit of a typical light-aircraft DC alternator Figure 7-6. A typical light-aircraft Dc alternator system  The overvoltage warning light turns on when the master switch is first closed, and it turns off when the engine is started and the alternator produces the correct amount of voltage.  If the voltage gets too high, the overvoltage protector opens the alternator field circuit, which turns on the overvoltage protector opens the alternator field circuit, which turns on the overvoltage warning light, showing that the alternator has been shut off because of an overvoltage condition.  The capacitor installed between the battery input of the voltage regulator and ground acts as a shock absorber. During operation, the electric motors in the aircraft can produce a spike of voltage in the electrical system high enough for the overvoltage protector to sense, which prompts it to open the alternator field circuit, shutting off the alternator. To prevent this, the capacitor absorbs the spike so it will not trip the overvoltage protector. A typical aircraft ground-power circuit Starter circuits LANDING GEAR CIRCUIT
 The squat switch in the circuit is mounted on one of the structs so that it’s in one position when the air plane weight is on the landing gear, and in the other position when there in no weight on the wheels. The purpose of the squat switch in this circuit is to prevent the gear from being retracted while the aircraft is still on the ground. The hydraulic pressure switch is used to turn off the pump motor in the event hydraulic pressure exceeds its limits. net EMF net EMF  If any of the limit switches are in a NOT UP or a NOT DOWN position, a red UNSAFE light will illuminate. But when the landing gear selector switch is in the LANDING GEAR DOWN position and all three gears are down and locked, the light will be out.  Also, if the selector switch is in the LANDING GEAR UP position and all three gears are in the up position, the light will be out. If the airplane is on the ground with the squat switch in the GROUND position, and the landing gear selector switch is moved to the LANDING GEAR UP position, the warning horn will sound, but the landing gear pump motor will not run. END OF CHAPTER 7

linairm 发表于 2011-10-22 20:28:27

这个东东真好

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Chapter 7 Aircraft Control Circuitry