How does the A320 electrical system work in a simulator?
The Airbus A320 electrical system normally uses two engine-driven generators to supply separate AC buses, while transformer rectifiers produce DC power. On the ground, external power or the APU generator can supply both sides; batteries provide start-up, transition and emergency power. In a flight simulator, the exact logic depends on the aircraft add-on.
In real-world A320 operation and detailed flight simulation, most source selection and bus switching is automatic. The pilot establishes a valid power source, keeps the normal generator and bus controls selected, and uses the ECAM electrical page to confirm what is actually energised.
What powers the A320 electrical system?
The normal electrical sources are the two engine generators, the APU generator, external ground power and two aircraft batteries.
| Power source | Normal purpose | What to expect in the simulator |
|---|---|---|
| Engine generators 1 and 2 | Primary source in flight, normally supplying AC BUS 1 and AC BUS 2 respectively | Each generator takes over its side after the associated engine stabilises |
| External power | Ground supply without running the APU | The ground unit must be connected before EXT PWR shows AVAIL; pressing the button connects it |
| APU generator | Ground power and an available backup source in flight | It can supply both main AC buses when the APU is available and the generator control is in its normal position |
| Batteries 1 and 2 | Initial power, APU starting, changeover support and limited emergency supply | They do not normally power the entire cockpit for sustained operation |
| Emergency generator | Essential power after a major in-flight generation failure | Only detailed add-ons reproduce its RAT, hydraulic and load-shedding logic fully |
The A320 does not normally parallel its AC generators. Contactors connect the selected source to the appropriate buses, while the automatic bus-tie logic allows one suitable source to supply both sides if necessary.
How do the A320 AC and DC buses work?
The A320 distributes generated power mainly as 115-volt, 400 Hz three-phase AC, then converts part of it to 28-volt DC through transformer rectifiers.
AC BUS 1 and AC BUS 2 supply most high-demand equipment. The AC essential bus normally receives power from AC BUS 1, with an alternate feed available from AC BUS 2. Transformer rectifiers supply the DC network, while essential, battery and hot buses preserve selected services under abnormal conditions.
A static inverter can convert battery DC into limited AC power in certain emergency configurations. This does not mean the batteries can replace the normal generators: non-essential buses and equipment are shed to preserve the systems needed to control and monitor the aircraft.
How do you power an A320 from cold and dark?
Use the batteries to wake the aircraft, then establish external power or APU generator power before configuring the rest of the cockpit.
- Select BAT 1 and BAT 2 on. This energises the limited battery-fed network and allows you to check battery condition. A mostly dark cockpit at this stage is normal.
- Choose a ground power source. For external power, connect the ground unit through the add-on's ground-services controls, wait for
AVAIL, then pressEXT PWR. Alternatively, start the APU and wait for its available indication. - Confirm the generator controls. APU GEN, GEN 1, GEN 2 and BUS TIE should normally remain selected on or automatic, with no
OFForFAULTindication. - Check the ECAM ELEC page. Verify that the chosen source is connected, both main AC buses are powered and the displayed voltage and frequency are normal.
- Start the engines. As each engine reaches stable speed, its generator normally assumes responsibility for the associated AC bus.
- Remove the temporary source. Disconnect external power or shut down the APU only after confirming that both engine generators are online.
The APU generator supplies electricity, but APU bleed air normally provides the pneumatic energy that turns an engine starter. Those are separate functions. Our worked Fenix A320 power-up and engine-start sequence shows the process in a detailed MSFS aircraft.
What happens if an A320 generator fails?
A single generator failure is normally handled by automatic bus switching, allowing the remaining engine generator or the APU generator to supply both main AC buses.
Some non-essential loads may be shed, especially when only one generator remains. The crew verifies the new configuration on ECAM and follows the displayed procedure rather than repeatedly cycling electrical switches.
If both main AC sources are lost in flight, the batteries initially support essential equipment. When operating conditions permit, the ram air turbine deploys and supplies hydraulic pressure to the emergency generator, which then powers a reduced essential network. The RAT is not itself the electrical generator; the relationship is covered in our A320 hydraulic-system explanation.
At low speed or on the ground, emergency-generator availability is more restricted and battery endurance is finite. Simplified simulator aircraft may skip the transition entirely, deploy the RAT visually without modelling its electrical effect, or keep equipment powered that should have been shed.
Why are the A320 displays dark even with the batteries on?
Most dark-cockpit problems come from mistaking battery power or an available source for a source that is actually connected.
- External power says AVAIL, not ON: the ground source is valid but has not been connected. Press
EXT PWRonce. - The ground unit is missing: many add-ons require it to be attached through an EFB, tablet or ground-services panel before the overhead button works.
- Only the batteries are on: connect external power or start the APU. Batteries intentionally feed a restricted set of buses.
- A generator button shows OFF or FAULT: return it to its normal selected position if appropriate, then confirm that the relevant engine or APU is running normally.
- BUS TIE is off: this can prevent a single source from supplying both sides. Its normal position is automatic.
- A single display remains black: check that display's brightness control and any simulated display failure; the main electrical supply may be healthy.
- A saved failure has returned: persistent aircraft states can retain failed generators, discharged batteries or abnormal switch positions between sessions.
Use the electrical synoptic and ECAM messages rather than judging the system from one switch. Our guide to interpreting the A320 ECAM explains how warnings, system pages and crew actions fit together.
A mistake we see constantly is pressing IDG DISCONNECT while trying to reset a generator. This mechanically disconnects the integrated drive generator from the engine; in the real aircraft it requires ground maintenance to reconnect, and a detailed add-on may require its maintenance function or a complete aircraft reset.
Why does electrical behaviour differ between A320 add-ons?
A simplified A320 may treat electrical power as a basic on-or-off state, while a systems-focused add-on models individual buses, contactors, battery discharge, source priority, load shedding and emergency generation.
- Choose a simpler model when learning normal cockpit flows and basic engine-start sequencing.
- Choose a high-fidelity model when practising generator failures, RAT operation, abnormal ECAM procedures or battery-only configurations.
- Expect variant differences: A320ceo and A320neo packages share the same broad architecture, but indications, loads and simulated failure detail can vary with aircraft standard and developer implementation.
For Microsoft Flight Simulator, our comparison of A320neo add-on system depth helps distinguish aircraft that reproduce the electrical logic from those intended mainly for straightforward flying.