Controls

This Page is all about controls for your generator.

I remember the Navy days when we had the frequency control right at the control panel. The operator simply hit the switch one way or the other to raise or lower the RPM of the prime mover which raised or lowered the frequency.

DIYers can spend buckets of money buying commercial controls, but we may be able to emulate these controls for a small amount of money. 

Governor

 A typical engine governor is nothing more than a 'fly weight' pulling against a spring, as the RPM of the engine increases, the centrifugal force on the weights causes it to apply more force on the linkage.

Above:  Here's the Lister 6/1 Cam and governor assembly. Starting from the left, we see the cam lobe that runs the Injection pump, next is the governor sleeve that is connected to the Governor fly weights. As RPM is increased, the weights fly further out, and move the sleeve inwards towards the gear. A lever rides in the slot of this sleeve and moves in relation to the sleeve position. the force applied by the flyweights to the injection pump fuel rack will dictate the speed of the engine.

If we picture the flyweights pulling on the throttle from one direction, and an adjustable bias spring pulling it from the opposite direction, we complete the governor. If we increase the spring pressure, we increase RPM till the flyweights pull equally on the throttle and equilibrium is reached once again.

In the crude drawing above, we see the governor Lever coupled solid to the fuel rack, the further to the right the rack travels, the slower the engine turns till the fuel is shut off and the engine dies. If we disconnect the spring from the threaded rod at the left, the rack will close completely. If we turn the red knob to increase spring tension, the governor arm AND fuel rack will be moved to the left increasing the RPM. When RPMs increase, the fly weights pull against the spring and equilibrium is obtained once again, and the engine becomes governed at it's new speed. This green spring dictates the governing RPM of the engine.

Once you understand the simple workings of the governor, you can design your own Murphy switch (kill switch) or remote governor adjustment.

If you're at a yard sale, you might find an electric screwdriver for a dollar with a bad battery pack.  If you were to join the screwdriver and the threaded rod above, you could finely adjust the frequency from your control panel, just like the big boys. You could power the electric screw driver with one of those cheap wall wart power supplies.

 check out the switch above, this is all you need to control the motor, hold the switch to the left and the frequency drops, to the right, and the frequency goes up... simply let go of the switch when you have the frequency you want.

In the drawing above, we have added a solenoid. In it's unpowered state, it does nothing, and offers no resistance to the movement of the governor linkage. When the electrical connections are made, the solenoid overpowers the spring and the fuel rack closes and kills the engine.

Here's one of many configurations you could have for a simple 'Murphy switch'.  Again, we use a double pole double throw switch, but this time, it is not a momentary type. This switch can be flipped one way or the other and left there. When the engine is NOT running, the oil pressure sending unit provides a ground. When the generator is not running, the power supply is dead and provides no power to the solenoid, so it remains inactive. The switch Can be flipped to the right to disable the Murphy switch, once the engine comes up to speed the generator head provides power to the input of the power supply, the buzzer and light is activated to warn that the Murphy switch is disarmed. By this time the oil pressure is up, and the ground removed from the oil pressure sending unit. The operator can now move the switch to the armed position. The buzzer is silenced, the warning light goes out. A good sized capacitor across the power supply or a latching solenoid could assure that the gen set doesn't try and restart.

Of course there are other methods to kill the engine. You could build a spring loaded flap valve that sealed off the inlet side of the air cleaner denying air to the engine when a low oil pressure or high coolant temp is detected...

This page is nothing more than a place to start...