L-1011 Trainer: Generator Breaker Buildout

L-1011 Trainer - Power System Buildout

Work on the power system for the L-1011 continues. Yes, this has taken quite a while but getting the power system right is somewhat the foundation for the entire simulator, especially, creating the systems to work in a way that they act realistic.

In the previous posting I showed you the AC Tie Bus buildout. Today, we continued to work on the generator breakers. There is a power generator breaker for each on-board generator (APU, ENG1, ENG2 and ENG3) that is used to power its respective power bus. The APU is switched directly onto the AC Tie bus while the ENG1, ENG2 and ENG3 generator powers the respective AC Bus1, AC Bus 2 and AC Bus 3. Each AC Bus can be tied onto the AC tie bus to form a combined and highly resilient power system. 

The image below shows the row of four (4) generator breakers with APU, ENG1, ENG2 and ENG3 from left to right.

L-1011 Trainer - Power System Buildout - Generator Breakers

Next, let's look at a number of examples showing how the AC Tie bus can be powered from different sources. By the way each AC Bus also drives a Transformer Rectifier (T/R) that supplies the aircraft's DC system with power. 

In the following images solid yellow lines indicate AC power and dashed yellow lines indicate DC power. 

Example 1: Aircraft Powered from External Power Source

So here we could be at the gate with power coming from the ground power connector or we could be pulled off somewhere into a parking position powered by a ground cart.

L-1011 Trainer - Power System Buildout - External Power on Bus

You see the green "AVAIL" light indicating that External Power is available an the "ON" light above it indicating that we selected the toggle switch to "on" and that the external power got switched directly onto the AC Tie bus. All three AC Tie Bus Breakers are closed as indicated by the white flow bars. The image below shows the power flow.

L-1011 Trainer - Power System Buildout - External Power Flow

Example 2: Aircraft Powered by Engine 2 Generator

In this example (which is not so typical) we would still be connected to a ground cart or external power (green AVAIL light) however, the external power is not switched onto the bus. Instead, we are powering the AC Tie bus with power coming from the #2 engine generator. In this case, of course, engine two would be running and producing power.

L-1011 Trainer - Power System Buildout - Engine 2 Generator Power on Bus

The image below shows the power flow from the engine #2 generator to AC Bus 2 and because all three AC Tie Bus Breakers are closed we are also powering all the remaining buses from the engine 2 generator.

L-1011 Trainer - Power System Buildout - Engine 2 Power Flow

Example 3: Aircraft Powered from APU

In the final example we see a typical scenario of an aircraft that has either just pulled up to the gate or is about to leave the gate. Here we have switched from External Power (or Ground Power) to the APU. You can see that the APU generator breaker (top left) has been closed and is providing power directly to the AC Tie Bus. Closing the APU Generator Breaker would have automatically tripped the External Power selector from the "ON" to the "OFF" position since APU Power and EXT Power can not be phase synchronized.

L-1011 Trainer - Power System Buildout - APU Power on Bus

The image below shows the APU Power Flow with all three AC Tie Bus Breakers closed.

L-1011 Trainer - Power System Buildout - APU Power Flow