Aircraft Electrical Power Systems Quiz

Aircraft Electrical Power System

• The system has a three-phase 115/200 V 400 Hz AC and a 28 V DC system.
• Electrical transients are acceptable for equipment.
• Commercial supply is secondary.
• Normal operation uses AC power.
• The system has 2 engine generators and 1 APU generator.
• Each generator can provide AC power to all bus bars.
• Some AC power is converted to DC for specific uses.
• Transformer rectifiers (TRs) supply DC power.
• Two main TRs (TR 1 and TR 2) supply up to 200 A of DC current.
• A third TR (ESS TR) powers the essential DC circuit from the emergency generator if main generators fail or if TR 1 or TR 2 fails.
• A fourth TR (TR Entertainment) powers the DC Entertainment bus for In-Flight Entertainment (IFE).
• If normal AC power fails, an emergency generator provides AC power.
• If all AC power sources fail, the system can invert DC power from batteries to AC.
• A static inverter transforms DC power from Battery 1 to 1 KVA of single-phase 115 V 400 Hz AC power. This power is then provided to part of the essential AC bus.
• The inverter automatically activates when the aircraft speed is above 50 kt, if only batteries supply power.
• The inverter activates at aircraft speeds below 50 kt if only batteries power the aircraft and both battery pushbuttons (BAT 1 and BAT 2) are on.

Engine-Driven Generators

• Two AC generators (GEN 1, GEN 2) provide power, one per engine.
• Each generator supplies up to 90 KVA of 115/200 V 400 Hz three-phase power.
• Generator Control Units (GCUs) control each generator's output.
• GCU functions include: frequency and voltage control, and protecting the network through associated generator line contactor control.

APU Generator and External Power

• A third generator (APU GEN) can replace either or both main engine generators.
• APU GEN supplies the same output as main engine generators.
• Ground power is available through a nosewheel connector to all busbars.
• A Ground Power Control Unit (GPCU) controls the external power contactor.
• A Ground and Auxiliary Power Control Unit (GAPCU) regulates and protects the network via the APU Electronic Control Box, controlling external power and APU line contactors.

Emergency Generator

• A hydraulic circuit drives an emergency generator.
• This generator supplies emergency AC power if all main generators fail.
• The emergency generator delivers 5 KVA of 115/200 V 400 Hz three-phase power.
• Its Generator Control Unit (GCU) maintains constant speed, controls output voltage, protects the network (with line contactor control), and controls start-up.

Batteries

• Two main batteries (each 23 Ah capacity) are connected to two hot buses.
• Each battery has a Battery Charge Limiter (BCL) to monitor and control charging and its contactor.