Airbus320 Cockpit Tour: #21 - Electrical Panel: What do all those buttons do?!

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The A320 Electrical Panel explanation.


The electrical power system consists of a three-phase 115/200 V 400 Hz constant-frequency AC
system and a 28 V DC system. Electrical transients are acceptable for equipment. Commercial
supply has secondary priority.
In normal configuration, the electrical power system provides AC power. The electrical power system
is constituted of 2 engine generators and 1 APU generator. Each generator can provide AC power to
all electrical bus bars. A part of this AC power is converted into DC power for certain applications.
In the event that normal AC power is not available, an emergency generator can provide AC power.
In the event that all AC power is not available, the electrical power system can invert DC power from
the batteries into AC power.

Two AC generators (GEN 1, GEN 2), one driven by each main engine through an integrated drive,
supply aircraft electrical power. Each generator can supply up to 90 KVA of three phase 115/200 V
400 Hz power.
Two Generators Control Units (GCU) control the output of their respective generator. The main
functions of each GCU are :
‐ Control the frequency and voltage of the generator output.
‐ Protect the network by controlling the associated generator line contactor.
APU GENERATOR AND EXTERNAL POWER
A third generator (APU GEN), driven directly by the APU and producing the same output as each
main engine generator, can replace either or both main engine generators at any time.
A ground power connector near the nosewheel allows ground power to be supplied to all busbars.
A Ground Power Control Unit (GPCU) :
‐ Protects the network by controlling the external power contactor, or
A Ground and Auxiliary Power Control Unit (GAPCU)  :
‐ Regulates, via the APU Electronic Control Box, the frequency and voltage of the APU generator.
‐ Protects the network by controlling the external power contactor and the APU generator line
contactor.
EMERGENCY GENERATOR
The blue hydraulic circuit drives an emergency generator that automatically supplies emergency
AC power to the aircraft electrical system, if all main generators fail. This generator supplies 5 KVA
of three-phase 115 and 200 V 400 Hz power.
A Generator Control Unit (GCU) :
‐ Keeps the emergency generator at a constant speed,
‐ Controls the generator's output voltage,
‐ Protects the network by the controlling the emergency generator line contactor, and
‐ Controls the emergency generator start-up.
STATIC INVERTER
A static inverter transforms DC power from Battery 1 into one KVA of single-phase 115 V 400 Hz
AC power, which is then supplied to part of the AC essential bus. When the aircraft speed is above50 kt, the inverter is automatically activated, if only the batteries are supplying electrical power to
the aircraft, regardless of the BAT 1 and BAT 2 pushbutton positions.
When the aircraft speed is below 50 kt, the inverter is activated, if only the batteries are supplying
electrical power to the aircraft, and both BAT 1 and BAT 2 pushbuttons are on.
DC GENERATION

TRANSFORMER RECTIFIERS (TRS)
Two main transformer rectifiers, TR 1 and TR 2, supply the aircraft's electrical system, with up to
200 A of DC current.
A third (identical) Transformer Rectifier, the ESS TR, can power the essential DC circuit from the
emergency generator, if the engine and APU generators all fail, or if TR 1 or TR 2 fails.
Each TR controls its contactor by internal logic.
A fourth Transformer Rectifier (TR Entertainment  ) powers the DC Entertainment bus bar
dedicated to the In-Flight Entertainment system (IFE) in order to take into account IFE needs.
BATTERIES
Two main batteries, each with a normal capacity of 23 Ah, are permanently connected to the two
hot buses.
Each battery has an associated Battery Charge Limiter (BCL).
The BCL monitors battery charging and controls its battery contactor.

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