Stepper Motor on Gas Generator

All depends on how you're going to couple the motor shaft to the generator throttle. How is the generator throttle actuated now? How much force (or torque) is needed to operate it? You also need to consider whether or not you want to retain manual control (you probably do).

I was just going to couple the shaft on the butterfly valve of the carb to the motor shaft. Hadn't thought about the manual operation. Maybe just a spring operated lever from the present govenor?

With direct coupling to a 7.5°/step motor, you'd have (at the most) 12 steps between fully closed and fully open. This is almost certainly too coarse, given that you'll only be using about 45° = 6 steps in practice. You may get away with half-stepping, which would give you 24 steps full scale, but if the price difference isn't prohibitive I'd go for 1.8°/step.

Remember to do your torque calculations!

[Caveat - I've never done this - just my feelings having dealt with engines and stepper motors separately].

The most common design for factory auto idle down is to use a simple solenoid that pulls the throttle down to the idle speed after so many seconds of no load condition and then releases when a load is sensed through a simple current sensing transformer and control circuit.

The problem with steppers is if a wire comes off while it was at wide open throttle once the load drops off or the over voltage and frequency spike kills the load devices it was driving your engine then spins itself to pieces.

The other thing is even if you have a box of odds and ends parts if you cant afford the fuel you probably cant afford the time and trouble it will take to make a home-made auto idle system that will be the least bit reliable either.

Well, now you mention it .... .

THe fuel cost isn't the real issue. the noise and the preception of being green is. Voltage and frequency spikes are a concern though, I'll pay attention to that. Thanks

You will create a whole lot of grief for yourself if you proceed down that path.

You don't want to be faffing around with a speed governing throttle that works just fine the way it is.

When a generator is unloaded it is already idling. It is idling at the nominal speed for the alternator to produce the correct line frequency. When it is loaded the speed drops momentarily until the governor opens the throttle to maintain that same nominal speed under load, and vice versa everywhere between no load and full load operation.

If you are still determined to lower the idle speed for possibly saving fuel then be prepared for overheating issues. I am assuming it is forced air cooled. Ditto for possible oil pressure issues.

If you really want to have a play then try to use the PLC to automatically (or remotely) start and stop the engine. I'm assuming it has electric start.

Do we have a capacity, make and model for this gas (LNG, LPG, wood gas, petrol...?) generator?

This is an old homemade setup. Approx 11 KW with and old gas tractor engine for power. The governor gear is broken, hence no more mechanical government. still working on finding out what engine type is but looks like no parts available. Don't really want to faff around anything but thought it might be a last hope before the scrap yard. Thanks

I see.

In that case consider making a governor with your PLC.

The throttle stepping increment is not critical and could be "tuned" with levers.

You still want to have remote start and stop capability with a 70% no load situation.

What's your location?

I'm over on the southwest corner of Colorado. Close to Paradise. My friend on New Mexico has this genset and all I know is secondhand info from them. When they return I'll be able to look at this first hand and really see what they have going. thanks

This thread does not make sense. How are you supposedly running and regulating the speed of the engine in the first place if the governor is out?

How about a picture of that engine being there is a good chance that someone here may be able to identify it?

If this is not running full load why not use battery storage? Deep cycle batteries and an inverter I think would cut down the running time to maybe 50%.

Bazzer

This might work. The unit is on a trailer so if there is enough room.. Next week I hope to get over to see the unit in person and see what might fit

Choice!!!

The CR4 panel is recommending sight unseen and the OP is asking for advice about a solution for a problem that he too hasn't seen yet.

Level playing field or weird?

I'm looking forward to your site survey findings.