Lecture Aircraft power systems 21PJE Palubní přístroje - LS 2012/2013 1
Digital avionics is more sensitive on supply voltage variations and high-frequency noise than analog alternatives. Requirements for electric power are specified by: MIL-STD-704 RTCA DO-160 MIL-STD-704 says what the user can expect to see in term of normal conditions, over and under voltage and frequency drift. It describes the electrical power quality for military aircraft and how the equipment is required to operate. RTCA DO-160: Environmental Conditions and Test Procedures for Airborne Equipment presents comparable information to MIL-STD-704 but for civil aircrafts. MIL-STD-704 The steady state AC power characteristics for standard military 115 V, 400 Hz Voltage (108 118) V rms Frequency (393 407) Hz Maximum DC component ±0.1 V Phase unbalance 3V Phase difference (116 124) deg 21PJE Palubní přístroje - LS 2012/2013 2
MIL-STD-704 115V, 400 Hz power system under various conditions 21PJE Palubní přístroje - LS 2012/2013 3
MIL-STD-704 115V, 400 Hz frequency allowance under various conditions 21PJE Palubní přístroje - LS 2012/2013 4
MIL-STD-704 28V DC power system under various conditions 21PJE Palubní přístroje - LS 2012/2013 5
MIL-STD-704 270 V DC power system under various conditions 21PJE Palubní přístroje - LS 2012/2013 6
RTCA DO160 it does not levy power quality requirements, but rather describes series of input conditions, testing conditions, and the behavior. It establishes 4 classes of equipment: Type A equipment is intended for usage on aircraft that use primarily AC power and any DC power is derived from transformer/rectifier units. Floating a battery on a DC bus is optimal. Type B - equipment is intended for usage on aircraft where DC power is supplied by engine-driven alternator/rectifiers or generators, and there is a battery of substantial capacity floating on the bus at all times. Type E equipment is power by only AC power. Type Z equipment may be used on all other types of systems covered by the document. 21PJE Palubní přístroje - LS 2012/2013 7
Comparison of aircraft electrical power: MIL-STD-704 x RTCA DO-160 21PJE Palubní přístroje - LS 2012/2013 8
Electrical systems Alternators Produces sufficient amount of electrical current at slower RPM by producing AC current that is converted to DC More constant at different ranges of engine speeds Lighter weight Less costly to maintain Less prone to overloading Generators Do not produce enough electrical current at low engine RPM to operate entire electrical system. Electrical needs often rely on battery, which is quickly depleted Requirements: higher reliability, working under difficult climatic conditions, lighter per power horse 21PJE Palubní přístroje - LS 2012/2013 9
Electrical systems Alternator Small aircrafts Alternator Engine DC generator Battery 21PJE Palubní přístroje - LS 2012/2013 10
Electrical systems Alternator Small transport aircrafts Alternator DC generator Engine Battery AC generator 21PJE Palubní přístroje - LS 2012/2013 11
Electrical systems Engine CSD Large transport aircrafts AC generator Battery Engine AC generator Large transport aircrafts Frequency alternator Rectifier Rectifier Battery 21PJE Palubní přístroje - LS 2012/2013 12
Min. diff. relay Battery Appliances DC gen. Exc. winding Carbon regulator Overvoltage relay DC generator with a carbon regulator and shunt excitation Carbon regulator 21PJE Palubní přístroje - LS 2012/2013 13
Contactless alternator Rotor Stator Switch off Power bus Terminal amplifier Power exciter Basic exciter Regulation CSD 21PJE Palubní přístroje - LS 2012/2013 14
Single phase stationary alternator Output voltage Square gen. 400 Hz Voltage regulation Power amplifier Transformer + Filtering Output observer Output Output current 21PJE Palubní přístroje - LS 2012/2013 15
Simplified diagram of a stationary alternator DC 28V to AC 115 V, 400 Hz 21PJE Palubní přístroje - LS 2012/2013 16
Twelve phase aircraft rectifier Filter Filter 21PJE Palubní přístroje - LS 2012/2013 17
Basic arrangement of a CSD unit 21PJE Palubní přístroje - LS 2012/2013 18
Simplified diagram of an electrical system for a large transport twinjet 21PJE Palubní přístroje - LS 2012/2013 19
Palubní síť soudobého vojenského letadla 21PJE Palubní přístroje - LS 2012/2013 20
Palubní síť soudobého dopravního letadla 21PJE Palubní přístroje - LS 2012/2013 21
ELEKTRICKÉ ZDROJE NĚKTERÝCH LETADEL TYP LETADLA HLAVNÍ ZDROJ POMOCNÝ ZDROJ ZÁLOŽNÍ ZDROJ L39 28 V 9 kw NÁPOROVÁ TURBINA 9 kw SS L410 28V 6kW L59 28 V 9 kw 28 V 6 kw ATR72 28V 12kW 115V 20 kva L159A 3x115V 35kW 28 V 5,6 kw L159B 28 V 15kW 28 V 5,6 kw 4 měniče 3x115V 1,7kVA CHALLANGER 3x115V 30kVA 3x115V 15kVA BOEING 737 3x115V 40kVA 3x115V 40kVA AIRBUS A310 3x115V 90kVA 3x115V 90kVA 28V 15kW, 3x115V 5kVA AIRBUS A320 3x115V 90kVA 3x115V 90kVA 28V 15kW, 3x115V 5kVA SOKOL BELL 412 BO105 28V 7,5kW,3x115V 40kVA, 28V 5,6 kw 28V 5,6 kw 21PJE Palubní přístroje - LS 2012/2013 22
Generator feeder lines based on B737 21PJE Palubní přístroje - LS 2012/2013 23
Electrical/electronics compartments 21PJE Palubní přístroje - LS 2012/2013 24
Flight deck control panels P1 captain s flight instrument panel P2 center engine instrument panel P3 first officer s flight instr. panel P5 overhead control panel P7 glare shield panel containing annunciator lights for each pilot P8 fire protection system control panel P9 weather radar display indicator and radio communication system selector controls 21PJE Palubní přístroje - LS 2012/2013 25
Overhead control panel 21PJE Palubní přístroje - LS 2012/2013 26
P6 and P18 panel 21PJE Palubní přístroje - LS 2012/2013 27