Uhm....I'm not even sure where to start so I'll just keep it simple.
1) The crowbar is on the FIELD, not the B-Lead
(Alternator with an internal voltage regulator (I-VR) don't have a field wire, so this discussion is about E-VR alts only.)
2) IF the Field circuit breaker never pops (i.e. the current never gets high enough to trip it....doubtful since it's shorted to ground, but irrelevant for this discussion), the crowbar still works PRECISELY as planned. Shorting the field to ground completely removes the field as quickly as possible. The crowbar works because it's FAST. It's FAST precisely because it shorts to ground.
You have wired the crow bar improperly if you connected it directly to the "F" wire. This is NOT aeroelect connections schematics. The CROW BAR is designed to short a CB NOT the field directly. I strongly suggest you get other opinions if you don't believe me, but its your plane. If I understand, and I do, you will just make smoke. The crow bar should be on the BUS voltage NOT the field wire, which is not buss voltage.
click:
[img=http://img262.imageshack.us/img262/6117/presentation1gk5.th.jpg]
I penciled in what I think you have, a dead short to Field to Gnd thru the Crow Bar! Ouch, one of a few things will happen, you will burn one or more of the following: crow bar, wires, alternator, voltage regulator or nothing will happen. The CB IS PART OF THE CROW BAR AND YOU HAVE KIND OF BYPASSED ANY WIRE PROTECTION! You will still have a BATTERY. The battery will still try to pump juice thru the CB, the VR and down the field wire. You may, pop the CB but you may do some other nasty things. WHY WOULD YOU NOT WANT TO SHORT THE CB, TRIP IT AND REMOVE THE POWER TO THE FIELD????
3) Once again, the breaker popping is incidental. If you want to wire your plane with bus bar and heat sinks that can take the full output of the battery, you can leave the breaker out, or size it so it won't trip, and the crowbar still works.
I hope you are right. I would bet a 6-pack you make smoke and nothing happens, except damaged wiring or VR or alternator.
4) Nuckolls did NOT invent the crowbar anymore than Apple invented Point and Click, Ford invented wheels or Boeing invented the airliner. It's a common technique when you have to immediately remove power from somewhere. It's common in power supplies. Your computer power supply probably has a crowbar in it.
I know that, as I stated previously Bob did not discover electricity, but A KEY COMPONENT if the Crow bar is the fuse or CB which it works in concert. You have isolated the crow bar to a direct ground with a VR between it and the wiring protection?
5) It's pretty trivial to whip up a device that merely opens the field instead of shorting to ground...uh... "grounding the field". The reason the crowbar doesn't do this isn't because we "old fashioned" engineers are brain dead and can't collectively figure how to do it otherwise.
I can't disagree with brain dead part and clearly you are a man on a mission, but your wiring architecture is non standard as they say. Have you tested this theory?
6) Yes, using a crowbar to remove power to both the regulator and an alternator contactor for an internally regulated alternator is a bit messy. It would be just as messy to do it with perihillion's gadget.
(Agree that is why I-VR alts should not have a crow bars and they don't need it.) Some feel that just removing power from the regulator is not enough because it doesn't necessarily remove the field in an IR alternator. I'm agnostic on the issue, to be honest.
I agree with all but the LAST paragraph if we are back to E-VR's. If there is NO power to the field it will collapse within milli seconds. Yes the CB takes time to trip. If you have an externally regulated alterantor, try turning the ALT off while it is running. What happens? It shuts down. Nuff said? (Note don't do this with I-VR alternators like Vans 60 amp, it is IC chip controlled and does not like being turned on while the alternator is spinning under load.)
Little definition, "FIELD" means magnetic FIELD of the rotor that is spinning in the Stator coil winding. If there is no power to the rotor (field) it collapses the field and the alternator can't produce power. End of story. I agree shorting the field may produce the same effect, but you still have a battery and hot wires if the CB does not trip. You may damage the alternators, VR and wires.
7) Perihillion's would probably work just as well as long as they actually ground the field when they trip (just based off what I read on the website).
(NO that is NOT what the web site says, it is designed for 10 amps flow thru and to act as a OFF switch to power NOT a crow bar.) Then again it's likely more fragile.
(how do you know that?) I'm not trying to push one solution or another. I'm just trying to clean up this misconception that's been floating around that crowbars are somehow bad or "contraptions".
One thing is your crow bar on the "F" wire is NOT seeing buss voltage. What voltage is it seeing? You don't know. Unless you test this rig, with your alternator and VR you really don't know what's happening. Even Bob's layout is semi flaky and finicky as is connected direct to the CB. Lets say for what ever the reason the VR goes wide open (unlikely, rare but could happen), the Crow bar clamps to ground, my guess is some "wire" will burn out in 1-2 seconds. The amps in the crow bar will be in the 1000's, but not for long. Than the OV will continue and/or you will have a fire. You may trip the CB and the OV will stop, if you are lucky, but you don't know until you test this SYSTEM. Bob's circuit is simpler and does not rely on the alternator or VR to act in a certain way. If the CB does not trip something must burn out. The solid state relay (SCR) is only good for a finite amount of current/amps/time.
There are many ways to skin a cat. As soon as you choose IR alternator and decide you're killing a contactor as well as the regulator, you're made a mess no matter how you do it or who's product you use, OK? Anyhow, I'm not trying to stir the pot here. I'm just stating facts as I see them based on my own education and experience. Anyone's free to dispute them and we'll just agree to disagree (or you can change my mind...)