PMag issue

[eddieseve]

Thanks for all the feedback guys, I agree I should have installed seperate circuit breakers after re-reading the instructions.

So I am going to opt for these;

http://www.aircraftspruce.com/catalo...rcuitbrkr2.php
Part number 11-04268

A little on the expensive side but they will also replace the PMag power switches in my panel.

Cheers

[Richard Connell]

Thanks for sharing your story Eddie.
Question though,
If you use that switch/cb combo, how do you perform the internal generator test preflight? Ie p-lead ungrounded, but no external power?
Cheers

[eddieseve]

Those switches only provide power to my PMags, I have a standard ACS ignition switch that handles grounding, ungrounding my Mags, plus engine start.

Cheers

[Walt]

Originally Posted by eddieseve

So I am going to opt for these;

http://www.aircraftspruce.com/catalo...rcuitbrkr2.php
Part number 11-04268

A little on the expensive side but they will also replace the PMag power switches in my panel.

Cheers

Those are the inexepensive ones, these are much better
http://www.aircraftspruce.com/catalo...klixon7270.php

[eddieseve]

Originally Posted by Walt

Those are the inexepensive ones, these are much better
http://www.aircraftspruce.com/catalo...klixon7270.php

Thanks Walt I feel much better now ;-)

Cheers

[Richard Connell]

Originally Posted by eddieseve

Those switches only provide power to my PMags, I have a standard ACS ignition switch that handles grounding, ungrounding my Mags, plus engine start.

Cheers

Ah right, that makes perfect sense. Ive got a CB, then a DPDT switch. OFF-RUN-TEST (OFF-ON-MOM).

cheers

[Walt]

Originally Posted by eddieseve

Thanks Walt I feel much better now ;-)

Cheers

Anytime dude

[N941WR]

For those of you that don?t know how the P-mags work, here is a primer:

If wired per the P-mag manual, the P-mags require a power and ground wire, as well as a P-lead. There is an optional tach signal pin and two others used for the ?jumper?. (See this thread for details on timing the P-mags.)

The power and ground should be supplied via 18 gauge (or heavier) wire. The Positive lead (pin 5) should have a 3 amp switchable circuit breaker, per the P-mag manual.

The p-lead grounds the P-mag, same as a traditional magneto.

With the switchable circuit breaker installed, you can pull it periodically to test the P-mag?s internal generator. (I test mine before every flight and at 500.5 hours I found one of my P-mag?s internal generator had failed. This should be a hint for those of you who are running an electronic ignition and one P-mag.) I would not recommend the use of a breaker-switch because they can be bumped off in flight. A pullable breaker is much less likely to pulled (turned off) in flight.

If you use fuses, then you have to add another way to test the internal generator function. A switch of some type will be required. The problem here is you have just added a lot of complexity to your ignition system, which is never good. It is best to wire them per the manual. This means grounding each of them to a separate engine case bolt and separate power feeds. As the maker of the EICommander who has helped a number of people (customers and non-customers), I cannot stress this enough!

Originally Posted by akarmy

FYI, I'm using fuses just fine...

How do you test the P-mag's internal generator?

Originally Posted by Bevan

...As far as I know, Pmags have a built-in crowbar over-voltage protection system...

Are you sure? I could find no reference to this in the manual.

[Bavafa]

Originally Posted by N941WR

How do you test the P-mag's internal generator?

Here is how I have setup mine,

The power source to PMAG goes thru a toggle (SPDT) switch with an inline fuse connected to this power line. The toggle switch closes the circuit either to the PMAG or an LED warning light, this is that if I accidently leave it in the off position to the PMAG, the warning light is lit.

At the run up area, I switch the PMAG power off and I do my normal PMAG test, also periodically check it with a real low RPM to test the generator portion of the PMAG. If the fuse is burnt, I will know it since the LED wouldn?t light up.

Many ways to skin the potato

[N941WR]

Originally Posted by Bavafa

...
Many ways to skin the potato

And cook one!

I was hoping you had a switch in the mix. Your light is a good idea!