Voltage Issue

[George Kretschmann]

I was entering a downwind leg to land and noticed my Voltmeter flashing it was flashing 10.5 volts. When I pulled up to the ramp and shut of the engines I checked the 50 amp GEN braker and it was pushed out. When I was ready to leave I cranked the left engine and the voltmeter read 13.5 volts then when I cranked the right engine the meter showed 13.8 volts. I was about 30 minutes into the flight home and the voltmeter went to 11.8 volt. I went to turning the non essential items. I cycled the "Gen" switches with no increase in voltage. I continue the flight with the voltmeter showing 11.5 to 11.6 volts. At the home airport neither alts were showing any voltage. What is going on?

[Charles Schefer]

George,

Sorry to hear of the difficulty. A few questions related to your electrical issue:

1) I assume you have the original 50amp generators and the original regulators and paralleling relay - is this correct?

2) What kind of battery do you have? Is it a flooded cell battery or a Gel or AGM (Absorbed Glass Matt) "non-spillable" battery?

3) Do you have the original battery cables or have they been upgraded / changed?

4) In addition to your volt meter do you have an ammeter? Can you say what the ammeter was doing and if so was it steady or was it jumping around?

- Charles

[George Kretschmann]

[Kristin Winter]

I am guessing that you have the Interav alternator conversion. I have the troubleshooting guides and manuals for that system, but I would have to read up on it. At the moment, there are no parts available for the Interav as the company stopped production and sold off there designs, etc. I would recommend just going to Plane Power. It has been rock solid in my aircraft.

[George Kretschmann]

[Charles Schefer]

I'm not familiar with the Internav but Kristen's trouble shooting guide may be the first best step. I asked about the battery because while rare, it is possible that an AGM battery with old regulators can have issues - there is another thread on that and the symptom would be an oscillating ammeter but it's not relevant here...

I do wonder if you may be having an issue with one or both regulators (I assume the Internav has two?).

I installed the Plane & Power TAL-70 this past Summer and while I haven't had the set-up long it seems great.

- Charles

[George Kretschmann]

[Charles Schefer]

George, when you refer to the "firewall" do you mean the bulkhead inside the nose section? I assume you don't mean the actual firewall behind each engine in the engine nacelles? I think of the bulkhead in the nose section as a firewall to... and maybe it is given there is a heater up there.

The original generator set-up in mine had a voltage regulator there for each generator and a "paralleling relay" in between. My new Plane & Power set-up just has two regulators, one per engine. The left regulator acts as "master" and the right as "slave". The left regulates both to match and does the "paralleling job". If either fails the one remaining takes on the master-regulator role.

Here are pics of the old and new set-up from my plane for reference...

Here's a pic I happen to have of the old generator set-up. This is form when I was doing a nut-plate and screw conversion on the nose section (replacing the old SouthCo fastners). You can see the two old regulators and the paralleling relay in the center.

The Plane and Power Set up (only partially wired in this pic when we were installing) just has the two regulators in a master-slave relationship.

- Charles

[George Kretschmann]

[Charles Schefer]

George, I totally follow you on the car firewall thing...

I bought my P&P TAL-70 from Spruce. I think the entire kit was $1,489 with everything plus $22.90 shipping. While it took time to install that same time or more could easily be spent trouble shooting the set-up you have.

My decision was easier... I had the old generators, wanted to go to alternators anyway and then my left generator destroyed itself so going the P&P route was a "no brainer" for me.

I suppose it comes down to how much time you want to spend troubleshooting recognizing you may have replace parts anyway. Here's a thought. De-cowl the nose and engines. You'll need to do that either way. Then Ohm out all the wires and make sure you don't have a wiring fault which could be an easy fix. If all the wiring checks out then it's probably a component and maybe the P&P upgrade is the way to go or just see if you can isolate the faulty component and replace that.

- Charles

[George Kretschmann]

[Charles Schefer]

At one point it was suggested that I could keep my old generators and use the Plane & Power regulators. That being the case I am sure you could use new regulators with the existing alternators. I guess one step further - building on my last suggestion of ohming everything out... would be to run the engines and have an ammeter and voltmeter to see what the alternators themselves are putting out.

- Charles

[George Kretschmann]

[George Kretschmann]

Here are the instructions for installing a Plane Power Regulator and using an Interav alternator.
REGULATOR INSTALLATION 12 – 1001
Page 2 of 3
Single Engine
READ AND UNDERSTAND ALL INSTRUCTIONS BEFORE APPLYING
POWER TO UNIT
1. Remove existing regulator and solid-state over-voltage module (if installed).
2. Install R1224/R1224B Regulator in same location as regulator being replaced. If mounting holes do not align add mounting holes
as required using acceptable methods, techniques and practices.
3. Connect GRND terminal to aircraft ground. It is critical that the regulator ground is connected to airframe ground. Without
this ground, the regulator and its internal overvoltage protection cannot function.
4. Connect the FLD terminal to the FIELD (brush) terminal of the alternator.
5. Connect the ENABLE terminal to the regulator/field power source (the wire from the cockpit ALTERNATOR FIELD switch which
is fed from a 7.5 max amp breaker). Note: In order for the over voltage protection circuit to operate the enable terminal must be
connected to an operational circuit breaker. (In the event of an over-voltage condition the over-voltage protection circuit will cause
the circuit breaker to trip removing all power from the regulating circuit.) Do not install R1224/R1224B in any aircraft that has an
automatic resetting circuit breaker in the enable line.
6. If the regulator being replaced has a connection to the AUX terminal on the alternator, connect this wire to the AUX terminal. If
not, install a jumper wire between AUX and ENABLE. Note: No connection to AUX terminal is necessary if an alternator out lamp is
not installed.
7. If the installer wishes to sense voltage at a source other than ENABLE terminal: remove jumper between ENABLE terminal and
SENSE terminal. Connect SENSE terminal to desired location.
For superceded versions of the R1224/R1224B (Rev B & previous) indicated by silver label, step 7 does not apply and no sense
terminal exists. Wiring of a ‘Sense’ terminal on these regulators will result in damage to the regulator.
8. If an ALTERNATOR out lamp is installed in the aircraft and is to be actuated by the R1224/R1224B regulator Connect the
negative wire of the lamp to the LAMP terminal of the R1224/R1224B regulator.
9. Remove the regulator cover and ensure that the internal jumper #1 and jumper #2 are set to the proper voltage for the
aircraft system. Refer to the picture on page 1.
10. With the engine running and the alternator switch turned on, using a small screwdriver, set the regulator’s voltage adjustment so
that the buss voltage, as measured at the ENABLE terminal is the desired value. Refer to aircraft maintenance manual or battery
manufacturer’s data for proper voltage setting.
11. Reinstall the R1224/R1224B cover.
Multi-Engine
1. For both regulators, perform steps 1-11 of the Single Engine procedure above.
2. Choose one regulator as the MASTER. It can be either. Connect the OUT terminal of the MASTER Regulator to the IN terminal
of the other Regulator.
NOTE: Both regulators must be the same part number. Adjustments to the voltage setting of each regulator may be made by

Guide M
INTERAV These are installed on aircraft, which have
been converted to an alternator from a generator by STC
SA334SW.
Use R1224.
Label the wires! Labeling the wires is important for
reconnection! If the ring lugs are damaged, crimp the
provided ring lugs onto the wires.

• Remove Interav regulator and over voltage
relay. The R1224 has internal over voltage
protection, so the Interav over voltage relay is
no longer needed.

• Ensure that the R1224 jumpers are set for 14V.
See Plane-Power R1224 Installation Drawing
12-1001.

• Install R1224 in the location from which the
InterAv regulator was removed.

• Remove the wires on both terminals of the
ALTERNATOR switch (on the aircraft panel).
Connect one terminal of the switch to the 5A
breaker where the wire to “Red-Pos” of the
Interav OV Relay was connected. Connect the
other terminal of the switch to R1224 #3
(Enable).

• Connect the GND (Ground) wire to R1224 #1
(GRND).

• Connect the Field terminal of the alternator to
R1224 #2 (FLD).

• Jumper R1224 #3 (Enable) to #4 (AUX).

• For R1224 Rev C and later: Ensure that there
is a jumper between R1224 #8 (SENSE) and #3
(ENABLE).

• Remove all disconnected and unused wires.
• If a warning lamp is incorporated, connect one
terminal of the lamp to R1224 #5 (Lamp) and
the other terminal of the lamp to the aircraft
bus through a 1A fuse or breaker. Be sure the
lamp is a 100-milliamp bulb or it will not work
properly.
Adjust voltage as necessary with engine running and
alternator enabled.
The installation is complete after testing.


There are 4 wires on the back of the alternator...

1- Field on alt to field on regulator
2- Ground on alternator to ground on regulator
3- Main charging wire to main bus
4- Reg wire on alt to.......?????? on regulator

The question is on the Interav alternator is the "reg" wire even used?? I don't think it is.
I think I need to run a wire from the main bus thru a 5 amp switch braker to the "Enable" lug on the Plane Power regulator.

Has anyone had this similar issue?

[Zach Grant L1011jock]

George,
Yes and Yes. First, you must replace both interav voltage regulators with the Plane Power regulators if you are going that route. You cannot have one Interav and one Plane Power due to the differences in the systems operation. The Interav has a temperiture compensated voltage thrue a zenier diod. The Plane power is simply a set the voltage and forget it, so in order for the alternators to share the load properly, you must have them both set to the same voltage. Now as to the wiring, yes, you must change the wiring somewhat. You probably already have the 5 amp breakers, so you just run the wire from those 5 amp breakers through the gen switches, and to the regulators "enable" port. Since the system is powered through the main bus and not through a feedback loop, you do not need the hot wire coming back from the alternator to the voltage regulator. Simply connect the existing "green" field wire that went from the over voltage relay to the alternator (the other green wire went to the gen switches and can be used for the enable wire) to the field port and then wire the two together as the instructions state (doesnt matter which is master or slave) and you will be in business.

Zach

PS. The Interav installation and troubleshooting documants can be found here: http://www.comancheflyer.com/NS/tech_ar ... nterav.pdf