Hi guys, new owner here.

Doing the Plane Power alternator conversion and am thoroughly confused with the wiring.....

Here's a diagram I got from Plane Power, who got it from someone whos done the conversion on a PA-30. Doesn't look right to me:

PA 30 wiring.pdf

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Here's the diagram from the instructions:

Twin Engine wiring.pdf

(173.23 KiB) Downloaded 17 times

And here's the generator system schematic from the service manual:

I've removed the voltage regulators and paralleling relay and bolted the 6ga wire from the gen output straight to the 50a circuit breaker.

Here's the dilemma: The new voltage regulators are set up to be supplied with bus voltage when the master and gen switches are on, through the "enable" terminal. The original system doesn't wire the gen switches through the bus.

Should I run all new wires through the bus, to the gen switches, then to the enable terminal? I could then use the existing wire that went from the generator to the paralleling relay and reroute is to be used as the "aux" wire for the inop lights......

OR...as shown on the hand drawn schematic, I could wire the "enable" terminal straight to the bus (through a 5a circuit breaker), and use the existing "field" wire to switch the alternators on and off. This doesn't seem quite right to me, but looks like someone has done it.

Thanks in advance!!

Justin Hawkins

Justin,

Welcome to the Forum. Folks have done this in the past may post and help. My 39 came with alternators so I can tell you others have been very happy with the end result of the PP conversion.

I am not sure I completely understand the question. I have done this a couple of times. The first schematic is a minor alteration of the STC, but using a split master switch to control the field circuits. However you run it, it still needs to get power from the bus.

I used Tyco W31 switches with built in 5A breakers for my enable lines to the voltage regulators. I installed them where the old generator switches were in the panel using 18ga wire. Bus connection to each switch, circuit protection via the built in breaker, then ran each out through the firewall to the new regulators.

I didn't have the breaker panel space in the floor to add 2 more 5A CBs down there so this was a good alternative. I installed the orange warning lights below each switch.

Tim

Thanks for the help everyone! I think I've got it figured out now. The original master and gen switches aren't wired into the bus so that complicated things, and the hand drawn diagram is sort of a patch to make it work. The hand drawn diagram doesn't show any bus voltage going to the field at all, with the enable circuit instead getting power from the bus. It also shows the sense terminal on the reg as having no connection, so how would the reg know when bus voltage is dropping?

I think I'll order some W31 breaker switches as Timothy suggested (thanks!) and follow the wiring diagram in the STC instead of the hand drawn one. My only debate now - do I run a new wire for the aux, run the old parallelling wire as the field, and get rid of the old field wire, Or do I remove the old field wire from the master and gen switches, splice it together, and use it for the aux. I imagine it's been done both ways.

To clarify, did most owners that have done this install completely bypass the master switch for the enable or field circuit?

You are not going to completely bypass the master as the master powers the bus, but if you mean directly in the field circuit, my guess is that most do not run through the master switch.

My twin is a 69 C model. That year Piper went to rocker switches instead of toggle switches. With the rocker switch form factor, you can obtain a split master switch where each half control the field to its respective alternator. If either side is activated, then the master relay is also closed, powering the bus. I obtained a split master, and used the W23 breakers that were already wired to the bus to take the power from the bus, routed through the split master, and the to the regulator. On an older aircraft, I would either route through the two generator switches or remove those and use the W31 breakers.

My W31 breaker/switches are supplied power from the master switch controlled bus, so the Master has to be on in order to pass power to each enable circuit.

Tim