ALT field switch... why, really?

[juscash]

The alternator field is the only circuit breaker in my electrical system. Every other circuit uses a fuse per the AeroElectric Connection. 800 hours and no problems.

[WenEng]

Originally Posted by DanH

.... Is that draw for a 60 amp or 70 amp unit?
FWIW, I just use a pull-able breaker for the field. Alternator field is always on with master on, unless I pull the breaker.... .

That would be a 60 amp PlanePower alternator. VPX is my ''pullable breaker''. By design, I did not install an Alternator Field switch. Its always on if the Master is on unless I ''pull'' the breaker by bringing up the VPX on my EFIS screen.

[Dan Langhout]

Originally Posted by DaleB

<snip>In an RV, I think a DP3T OFF/BAT/ALT switch would do the job perfectly well. And, with that setup I can use a fuse for the field supply.</snip>

I use a OFF/BAT/ALT toggle switch as you describe AND a pull-able circuit breaker for the field (they are literally right next to each other on the panel). The BAT position for the aforementioned ground ops reasons; the breaker so I have a chance to reset in flight from a spurious trip.

BTW - I have seen close to 5 amps for the field draw with the engine off (amp difference on the Skyview between the BAT and ALT positions) using a Planepower, 60 amp, internal regulator alt.

[tgmillso]

Hi All,
I like the sound of this off/batt/alt+batt switch. Does anyone have a B&C or Stein part number for this switch that they can point me to, as I can't seem to find it on their websites?
Thanks.
Tom.

[Stevea]

B&C S700-2-10 or Stein SKU: 2-10

[tgmillso]

Excellent. Thanks.

[dutchroll]

Stein SKU: LT-003 is the DPDT locking toggle variant like I have for off/batt/batt+alt

It's a bit on the pricey side (pretty high quality switch) but just my personal preference for a master was to have one which needs a very deliberate action to switch on, because my aircraft lives in a public access warbirds display hangar. Not essential to go that upmarket though. The others mentioned here would be fine too.

[gyoung]

My regulator has built-in overvoltage protection that latches the field off if triggered. In the event of a nuisance trip, the VR power has to be cycled to get the alternator back online so a field switch or pullable breaker is in order.

[Snowflake]

Originally Posted by DaleB

Very true. But I think that's theoretical. I can't recall anyone I know who has had an electrical fire (or even substantial smoke) in a car built in the last 20 years or so, and some of my kids and their friends have driven some pretty sketchy cars.

I know i'm replying to a two year old comment, but as the thread was revived I thought this would be of note... As luck would have it, two nights ago this happened in front of my neighbour's house. A guy was driving along, smelled something funny followed by smoke coming from under his dash... He pulled over, and just had time to grab his valuables before the flames started. 2005-ish Chevy Cavalier.

It took four city and district fire trucks, and a brief visit from the airport fire truck (which used up a good supply of foam on it) to put the fire out... An hour and a half later.

Video hosted on my Google Photos site, the link should work for anyone who has it... About 1min long, large fireball.
https://photos.app.goo.gl/KQRwadcDsIYwacIg2

[rzbill]

Originally Posted by Snowflake

Chevy Cavalier.

Fortunately, no loss.

I made the mistake of owning one for a year or two.