172 electric system

[757200ba]

Hello, I'm taking the class  CFI ground school.So i need to give a class about the 172 electric system.I have the POH and all that but i wanted to have a more small and compact idea.
Any ideas thank you very much.

[BFMF]

I'm in school to become an Avionics Tech, but I havn't gotten that far yet...

[beaky]

Sorry about the double-move, there... but at any rate, it's better off not in the Lounge.

I'm not a CFI, but as a PPASEL I had to learn the basics of that airplane's electrical system, to the extent I could explain it... I'd imagine you've already done the same, so...?

One suggestion I can offer is that you simply describe the flow, from te alternator onward. It's not a complicated system, really.

[Splinter562]

I agree that the schematic in the POH it a bit too complicated for an introduction to the electrical system. The way I'd go about explaining it is simply to say the the aircraft (typically) has two power buses. The main bus powers aircraft systems such as flaps, stater, and fuel gauges. The avionics bus powers the radio stack. Then I'd explain that the main bus is powered by either the aircraft battery or the engine-driven alternator (tie conversation to the two sides of the master switch). The avionics bus gets its power from the main bus via the avionics power switch. The last thing I'd introduce would be the circuit breakers between the bus and the actual device for protection and isolation.

You can make a simplified diagram to illustrate this. Draw two rectangles labeled main bus and avionics bus, connected by a switch. Then on one side of the main bus show the battery and alternator as feeding the bus. On the other show the devices that take power from each bus (with a breaker between the bus and the device). You can use arrowheads to indicated the direction of "flow".

While not schematically accurate, this is functionally accurate and a lot simpler to grasp for new students at first. Once they've got this down, then you can fill in the details.

[757200ba]

Thank you very much for the reply. Its just WONDERFUL. I had on my mind , explain by a scheme and let the POH just for some more detailed info.
I will draw the way you describe, its very practical and clear, my Professor told me to give an explanation on a commercial level to last between 25 to 30 min.So i don't need to go that deep.I always can through some "head" questions, about differences between for eg. alternator and generator. and DC an Ac current . And after explain the basic, end up with what procedures to have in case of emergencies.
I will try my scheme but schemes are welcome.
Thank you once again for such fast replies.
THANK YOU