cjensen wrote:The plug would serve as a sort of "kill switch" on the ground to completely disable the Pmags. Would prevent an accidental spark if the prop were turned, and theft.
Yep this one is throwing me too... You have a DPDT switch that disconnects power and shorts the Kill lead to ground when in the off position but then you have a plug that when inserted is going to power up the power lead when the switch is in the off position.
I am P-Mag stupid so please elaborate on what this is doing and why you would want it that way.
Also seems like a great place for a person to stick a plug in there that does not belong leading to smoke escaping from something....
Last edited by Brantel on Mon May 19, 2008 2:53 pm, edited 1 time in total.
Brantel (Brian Chesteen),
RV12-IS, #121606, N912BC - Building Now!
RV10, #41942, N????? - Project Sold
RV-7/TU, #72823, N159SB - SOLD
Don't read too much in to that plug guys...it's just an idea**, and I have no idea if it's a good one or not. I saw it on another schematic, and thought "Hmmm, that's neat."
**Remember, I HAVE NO IDEA what I'm doing when it comes to wiring yet...
I would put in a pullable breaker for each PMAG. That way you can test the internal generator on each PMAG on runup - leave the switch on and pull the breaker feeding the PMAG with juice from the bus.
Mike Bullock http://www.rvplane.com RV-7 | Superior IO-360 | Whirlwind 200RV Garmin GTN650 | GRT Dual Sport SX EFIS
Status: FLYING!
Then how ya gonna test the internal generators on the PMAG's? Its no fun to find out their not working if your electrical system goes kaput on takeoff!
Mike Bullock http://www.rvplane.com RV-7 | Superior IO-360 | Whirlwind 200RV Garmin GTN650 | GRT Dual Sport SX EFIS
Status: FLYING!
Since you are against pullable breakers.....Perhaps two switches - one for the P-Lead, the other for the 12v input. Flip on the P-Lead, off the 12v input and you can test the internal generator. Either way its a complex solution. I am provisioning for a pullable breaker when I eventually swap out one of my mags for a PMAG.
Mike Bullock http://www.rvplane.com RV-7 | Superior IO-360 | Whirlwind 200RV Garmin GTN650 | GRT Dual Sport SX EFIS
Status: FLYING!
how about a double throw toggle switch? It'd work kinda like a progressive transfer switch, but it doesn't actually need to be a fancy progressive transfer switch:
Switch DOWN: grounds P lead, disabling mag (I guess the PMAGs still work that way!)
Switch CENTER: un-grounds P-lead, enabling mag but NOT POWERING IT (self-powered mode)
Switch UP: still not grounded, but feeds power to the PMAG (normal operations).
Then, your run up could involve switching the left mag off completely, noting the drop, then switching right mag to unpowered. If the engine dies, the internal generator doesn't work. Bring left mag back up to fully powered, switch right mag off, note the drop, then switch left mag to unpowered.
Anyone following me? Am I off base here?
edit: It'd have to be some kind of progressive transfer switch afterall probably, but no big deal.
Ian
RV-7 SB, chugging toward final assembly
IO-360-C1C 200hp obtained.
Hartzell BA prop received.
James Cowl ordered.
N773WW reserved!
I am totally following you. If you went with a DPDT (ON-ON-ON style), you could have the down switch position be off, middle be PMAG generator only and UP being connected to the battery.
I think the S700-2-5 (ON-ON-ON) switch from B&C would be most suitable.
If you guys aren't following me, lemme know and I will put up a quick schematic.
Mike Bullock http://www.rvplane.com RV-7 | Superior IO-360 | Whirlwind 200RV Garmin GTN650 | GRT Dual Sport SX EFIS
Status: FLYING!
I was just reading about this very thing (switches) and P mags this morning in the Nuckolls manual (read it cover to cover). It's text is in the last couple pages of the Z section right before the schematics. I didn't pay much attention to it since I'm not a P mag guy.
Chad and I have been exchanging emails today about the wiring diagram and so I thought I would check out this thread.
Let me explain a few things about the design that he is copying.
1. This wiring diagram is for a simple day/night VFR ship. Thus no E-bus is required, per Aeroelectric Bob.
2. The "Always Hot Bus" provides power to three things:
a. Keep alive circuits for the electronics (Dynon's in my case)
b. Provide power to a "courtesy" interior light for boarding w/o turning on the master.
c. I have a 7.5A breaker with 18 AWG wire running to a 2nd power port so the battery can be charged / maintained w/o pulling the cowling. (I've used it twice. Once in Michigan when it was 15* in the AM, can't remember the nighttime low. And once when 'b' above was left on by a Young Eagle. Duh on me for not checking when I parked the plane.
3. The prior mentioned wiring discrepancies were noted in my installation and were corrected prior to the plane leaving my basement. I just haven't updated the drawing Chad copied.
4. P-Mag wiring should be to the main bus, per E-mag Air.
5. Per E-mag Air, there is no need to test the internal generator, thus they recommend you pulling the breaker only occasionally.
6. The P-mag wiring diagram Chad posted is based on the Aeroelectric Bob drawing Z-33 which has since been pulled. This wiring diagram was believed to be the cause of the lost timing the early P-mags experienced. This issue was resolved with a software upgrade last summer. (Check with E-mag to make sure you are running the proper software version prior to your first flight.) Even with the software update, E-mag Air does not recommend the wiring in drawing Z-33. (I continue to run mine in this configuration and the mag check is simple. Increase the RPM, turn off the right P-mag, switch the left mag from ship's power to self power, switch the right P-mag to self power, turn off the left P-mag, turn the right P-mag to Ship's power, turn the left P-mag back to ship's power. No need to pull the breaker.)
7. The Ground Maintenance plug can be used as an anti-theft deterrent and could be replaced with a simple switch. However, its main purpose is to ground the P-mags and put them setup mode. To time the P-mags you bolt them in, in any orientation, turn the prop to TDC, put the plug in, power them up (turn on the master w/ the mag switches off), note the LED on each P-mag should be red if this is the first time they are timed, blow in the vacuum advance hose leading to both P-mags, the LED will flash red, blow in the hose a 2nd time, the LED will flash green indicating they are timed, turn the master off and back on and note the LED, it should remain green. Time to start the engine.)
Regarding the theft deterrent part of this setup, I’ve said this before, you would have to be very dumb to steal a homebuilt. Maybe grab the radios but even an airplane thief probably isn’t dumb enough to take a homebuilt.
(Added Item #7)
Last edited by N941WR on Tue May 20, 2008 12:37 pm, edited 3 times in total.
I am totally following you. If you went with a DPDT (ON-ON-ON style), you could have the down switch position be off, middle be PMAG generator only and UP being connected to the battery.
I think the S700-2-5 (ON-ON-ON) switch from B&C would be most suitable.
If you guys aren't following me, lemme know and I will put up a quick schematic.
Mike and Ian
You two are correct on all counts, including the switch number I used.
Here is a simple diagram I just put together on how I perform my mag check:
Chad, You mentioned you were not using the expensive circuit breakers (pull type). I trust you are, at least, using fuses. They, or circuit breakers, are used to keep the smoke in the wiring. If you don't have the protection and let the smoke out, you will have a BIG problem!!
Dan N742DA
Dan A wrote:Chad, You mentioned you were not using the expensive circuit breakers (pull type). I trust you are, at least, using fuses. They, or circuit breakers, are used to keep the smoke in the wiring. If you don't have the protection and let the smoke out, you will have a BIG problem!!
Dan N742DA
Yep! I will be using fuses with a fuse block from B&C.
cjensen wrote:
Yep! I will be using fuses with a fuse block from B&C.
I am also gonna go the fuse block route to from B&C..........I just need to figure out how many blocks I need. So far:
1) Battery Buss
2) Main Buss
3) E-Buss
4) Avionics Buss
5) Aux Battery Buss
Its going to be quite busy in that subpanel!
Also, I just started buying stuff for wiring. Right off the batt I blew $200 between B&C and the welding supply store (#2 cable and cheap crimper). This project is starting to nickel and dime me now!
Mike Bullock http://www.rvplane.com RV-7 | Superior IO-360 | Whirlwind 200RV Garmin GTN650 | GRT Dual Sport SX EFIS
Status: FLYING!
cjensen wrote:Everybody says that wiring an airplane is the START of the nickel and dime charges...
So very true!
Gang,
Here are just a few things to think about as you design your electrical system and build it into the plane:
1. Some systems should have pullable breakers just in case the item they are feeding "hangs". This includes the flap motor, autopilot, alternator excite field, and possibly the P-mags, if installed.
2. If you are installing fuses, make the fuse panel(s) so they can flip down to make future maintenance easier. There is nothing worse than sliding under the panel on your back to do some maintenance or change a fuse and I'll guarantee you will blow at least one fuse in your early testing phases. Besides, it is difficult to figure out which fuse is blown when the fuse block is mounted vertically on a rib.
Just my opinion and you know what they say about those and everyone having one.
Yep! I will be using fuses with a fuse block from B&C. 