Flyer59 wrote:
The SR 22 has that too
Where exactly are the crossover switches?
no, that diagram is for my airplane, a 2006 TKS but NON-FIKI, so you are right.
Crossover switch: All i know is that the system will automatically use Alt 2 once BAT 1 is empty. So while the redundancy is not perfect you do have some time after an ALt 1 failure, and if you really need to fly on the essential bus, you still have radios and navigation.
The newer Perspective versions have a better redundancy because of the more powerful ALT 2 and becasue of the second ADHRS system.
the system will automatically use Alt 2 once BAT 1 is empty
That must be implemented via a second voltage reg set to a lower bus voltage.
It would be set to 27.5V (if you want an instant backup if ALT1 fails) or about 23V (if you want it to come online once the #1 battery is approaching empty). The latter mode seems pointless, unless ALT2 is so small that it is a last-ditch option, after a lot of load shedding done manually by the pilot.
The TTX has two identical systems.
Yes, there’s a second voltage regulator (FCM) in the Master Control Unit. In the later SR22’s it’s a 100 Amp + and 80Amp Alternator. ALT 1 is regulated to 28 volts and ALT 2 is regulated to 28.75 volts.
TTx:
Belt Driven Alternator, 28 Volts, 70 amps rated
• Gear Driven Alternator, 28 Volts, 70 amps rated
• Dual 28 Volt, 8.5 AH Batteries
• Dual Voltage Regulators, 28 Volt
Flyer59 wrote:
All i know is that the system will automatically use Alt 2 once BAT 1 is empty.
I doubt that’s true. It doesn’t make sense and it’s not in line with what you posted in #46.
If your system is configured with two main buses (one and two or left and right), each fed from a different generator, crossover switch allows you to bridge them so you can power both of them (the whole plane) from one “side”.
Yes, you are right. That cannot be done in my plane. Of course it’s not two main busses, see description above!
Peter wrote:
It would be set to 27.5V (if you want an instant backup if ALT1 fails)
ALT2 is actually set to 28.75 so it powers essential bus as long as it works. Under normal conditions, the two alternators split the work. Only when ALT2 fails the ALT1 powers everything.
Flyer59 wrote:
Of course it’s not two main busses, see description above!
I was just trying to explain to you what a crossover switch does (bridges buses; it’s similar to crossfeed in fuel systems).
Yes, I understand that (now :-))
I have learned a lot about Alternators in the last two days .. as always when something breaks. I know little about the stuff that always just works …
Why are the two buses different voltage?
