[macrafic]

2 questions on the E/P Mag portion of Z-13/8. 1. Purpose of having the P-Mag on the main bus and E-Mag on the battery bus? 2. With this configuration, how to test the self- powering capability of the P-Mag?

Can anybody enlighten me on these questions please?

 

[erich weaver]

They are wired to two different busses so that there are two separate power paths. A wiring problem on one path will not affect the other.

To check the self power feature, simply get your rpm up above 1000 or so and turn the power lead(s) off. Should keep running without a hitch. You can do this individually if you want by grounding the p lead for the unit not being tested to make it inoperative.

Erich

 

[macrafic]

They are wired to two different busses so that there are two separate power paths. A wiring problem on one path will not affect the other.

To check the self power feature, simply get your rpm up above 1000 or so and turn the power lead(s) off. Should keep running without a hitch. You can do this individually if you want by grounding the p lead for the unit not being tested to make it inoperative.

Erich

Maybe I have this backwards. I though grounding the P-lead would kill the mags and that, to test the P-Mag self-powering feature, you would leave the P-lead ungrounded while killing the power. Can anybody confirm?

 

[N941WR]

Why do you want to put the E-mag on the E-bus?

The idea of the E-Bus is to provide power to ?essential? items so you can land at the nearest airport and make repairs. The single P-mag will get you home in one piece. The single P-mag will get you home and if you are worried about running on just one P-mag, contact E-mag Ignitions about upgrading your E to a P.

The E-bus should only power your EFIS, a com and a nav radio and maybe landing lights. The rest is just additional load. I have seen some E-bus designs that might as well be called the main bus. Remember, things that transmit, like a transponder, use a lot of power. Besides, ATC can still paint you even with the transponder off. They just won?t know what altitude you are at. For that, you can tell them, assuming you haven?t run your battery down and your radio is useless.

An engine will most likely run just fine without being monitored until you get on the ground, thus let your engine monitor go dark. However, check the current draw, it might not be that much and if it makes you feel better knowing the big noisy chuck of metal up front is still making noise, put it on the E-bus.

One other minor thing, if you put in a backup battery, put it in a place where it is readily accessible and easy to change. Then put the backup battery on the same replacement schedule as your ELT battery. Yes, replacing it every two years may be costly but it sure beats the heck out of it only holding a 30 minute charge when you need it most.

Just my $.02, which you didn't ask for, but there it is.

 

[macrafic]

Why do you want to put the E-mag on the E-bus?

The idea of the E-Bus is to provide power to ?essential? items so you can land at the nearest airport and make repairs. The single P-mag will get you home in one piece. The single P-mag will get you home and if you are worried about running on just one P-mag, contact E-mag Ignitions about upgrading your E to a P.

The E-bus should only power your EFIS, a com and a nav radio and maybe landing lights. The rest is just additional load. I have seen some E-bus designs that might as well be called the main bus. Remember, things that transmit, like a transponder, use a lot of power. Besides, ATC can still paint you even with the transponder off. They just won?t know what altitude you are at. For that, you can tell them, assuming you haven?t run your battery down and your radio is useless.

An engine will most likely run just fine without being monitored until you get on the ground, thus let your engine monitor go dark. However, check the current draw, it might not be that much and if it makes you feel better knowing the big noisy chuck of metal up front is still making noise, put it on the E-bus.

One other minor thing, if you put in a backup battery, put it in a place where it is readily accessible and easy to change. Then put the backup battery on the same replacement schedule as your ELT battery. Yes, replacing it every two years may be costly but it sure beats the heck out of it only holding a 30 minute charge when you need it most.

Just my $.02, which you didn't ask for, but there it is.

Bill, I'm always open for $.02 worth!!! I'm not sure what I want to do yet. That is what I'm trying to determine. I was just re-iterating how AeroElectric has it on their latest Z-13/8 drawing and trying to understand it myself. I sent an email to Bob an AeroElectric, but that is usually not the best way to reach him. I may have to give him a call.

 

[erich weaver]

Maybe I have this backwards. I though grounding the P-lead would kill the mags and that, to test the P-Mag self-powering feature, you would leave the P-lead ungrounded while killing the power. Can anybody confirm?

Yes, correct. I don't see how this conflicts with what I said in my previous post. Sorry for any confusion though.

I have Pmags and use z-13/8, but have two switches for each Pmag, per the emagair instructions. The Aerolectric Connection may show some different switch arrangement, don't remember now, but regardless, the principal is the same for testing. Ground the p lead for any unit you want to disable. While running, cut the power to the unit you want to test for internal power capability.

Good luck
Erich

 

[macrafic]

I don't think I stated my initial questions very clearly.

While I understand the logic of having each mag on a separate bus, I'm not sure why AeroElectric chose the main bus (vs the battery bus) for the P-Mag, and vice versa for the E-Mag. What would the consequences be if the busses were reversed for the mags.

Second, I don't see, from his diagram, how one would check the self powering capability of the P-Mag, since it is wired to the bus without a switch.

Bob knows his stuff, so I'm assuming I'm missing something elementary here. Anybody out there that can clue me in?

 

[Subwaybob]

P-Mag and E-Mag

I don't think I stated my initial questions very clearly.

While I understand the logic of having each mag on a separate bus, I'm not sure why AeroElectric chose the main bus (vs the battery bus) for the P-Mag, and vice versa for the E-Mag. What would the consequences be if the busses were reversed for the mags.

It is this way because the P-Mag does NOT need power to run. The E-Mag does. Therefore if your main bus goes down, which your P-Mag is connected to it will continue to run. The E-Mag will not and therefore is connected to the E-bus (Battery bus) and will run until you run out of juice. So this gives you both mags until you run out of juice and then you will only have the P-mag. You do not need an E-Mag. The P-Mag is the next gen of the electronic mags... all of them IMHO.

Second, I don't see, from his diagram, how one would check the self powering capability of the P-Mag, since it is wired to the bus without a switch.

There is a wire to a single switch (SPST) in which you "ground" the mag to test it.

Bob knows his stuff, so I'm assuming I'm missing something elementary here. Anybody out there that can clue me in?

Yes, yes he does! Hope this helped.