Breakers

[Flybyjim]

I was looking at photos in the Show us your panel and noticed there are several panels that do not show circuit breakers, I am wondering where they are located and how do you access them during flight if needed?

[efwd]

Mine has a Vertical Power VP-X sport solid state circuit breaker box.
Eddie

[tracstarr]

I've never head of this system. This is why I love these forums. Just was researching them and this looks amazing, especially since I want to use an EFIS system.

[PaulSS]

This is a subject much discussed in electronics books and advice and I'm going down the fuse route, instead of CBs (mostly).

Questions that need to be considered are:

What items are there that are so critical to flight that you need to have access to them while up in the air? I have two ('backup battery' circuit for Rotax 912iS and battery isolation for a Lithium battery....madatory for the UK and, I think, a good idea). For these two circuits I'll have 30A CBs in the panel. For everything else, so what if I lose the radio, transponder, EFIS or iPad charger. Look out the window and do what we did before we got all that kit.

To me the more important thing is WHY has that CB popped? They don't do it just for fun and that means there's a snag with that system. Is being up in the air really the time to start trying to second-guess why your iPad charger has shorted? Do you need it so desperately that it needs to be re-set now or can you wait until you're on the ground?

Space, weight and cost are also considerations but I think the two points above are more important.

Because of all this I'm going down the fuses route. I'll have the fuse boxes (I'm using one as the main bus and a second as the avionics bus) under the panel where I can gain access to them but, realistically, only on the ground.

I like the Vertical Power system and I think electronic circuit breakers are a great system (MGL do a reasonably priced one) and if I were building an RV or similar then I'd definitely be looking at one. However, for my aircraft (a Eurofox) the flaps are manual, the trim is manual, wig-wags are pointless because the landing lights are tiny and in the nose and the starting system goes straight from the battery to the engine. Yes, I can use the ECB as a great way of programming and controlling the CBs but a lot of the functionality of the VPX would be wasted and that's why I opted not to go down that route. If I had all the gizmos above then I would be sorely tempted :)

So, to answer the question, the panels you see either have an ECB or they have fuses hidden behind the panel (or similar).

[Esser]

I have a very power heavy plane with two alternators, glass, and EFI. I am running a fuse block instead of CBs. The fuse block is the one on ACS. It has two sides so you can run an essential buss. I stayed away from the VP-X because I was going to run an EFI system. They may have figured work around but since they are slow blown fuses, any tiny spike would trip the breaker and people were
Losing critical items in flight like fuel pumps.

[Tom Waid]

In places that required both a breaker and a switch I've used breakers that combine both functions.

http://www.aircraftspruce.com/catalog/elpages/pbcircuitbrkr2.php

[Flybyjim]

This is all good reasoning for each person's situation. I can agree there are items we can deal with once on the ground.
Thanks for the reply.

[TJay]

I used Tyco switches. No Need for separate breakers with those.

[tracstarr]

I have a very power heavy plane with two alternators, glass, and EFI. I am running a fuse block instead of CBs. The fuse block is the one on ACS. It has two sides so you can run an essential buss. I stayed away from the VP-X because I was going to run an EFI system. They may have figured work around but since they are slow blown fuses, any tiny spike would trip the breaker and people were
Losing critical items in flight like fuel pumps.

Do you have any specific information about this? Or where I can find it? Since I'm also planning EFI I would like to know more.

[Esser]

Looks like you can do it, just need thorough testing.

Jan. 15/15 Service Bulletin Regarding Vertical Power VP-X and SDS

It has come to our attention that the VP-X electronic switching/ circuit breaker box does not use average current draw over several seconds to trip breakers like conventional thermal breakers do. It may trip during normal operation due to peak current transients over only a few milliseconds. This can lead the pulsing current of the ignition coils and injectors to trigger the breaker far below nominal current levels. We believe this could cause a serious flight safety issue and engine stoppage. Be sure to set the breaker values on the VP-X far higher than the nominal current draw on these circuits. Be aware that average current draw can increases with rpm and load so ground running may not allow complete testing of this condition if static rpm is lower than flight rpm and engine shutdown could occur in flight. Breakers are to protect the wiring, not the device. We recommend each 4 cylinder coil pack have a rating of at least 15 amps assigned when using the VP-X, each 6 cylinder coil pack at least 20 amps, 4 cylinder injector power at 15 amps, 6 cylinder at 20 amps and 8 cylinder at 25 amps. These are only recommendations, use this information at your own risk and these values should be thoroughly tested prior to flight at WOT and maximum rpm the engine will see in flight.

[tracstarr]

I reached out to VP-X and they state that currently there are no known issues with the Rotax fuel injected systems - and that their manual specifically has instruction on how to wire.

But as always, it's buyer beware I guess. I'll reach out to Rotax to see if there have been known updates and improvements with the VP-X from their view.