An ESD protection device having reduced trigger voltage is disclosed. The draper assembly includes a fore-and-aft draper that delivers crop material to a feeder house of the harvesting machine. A load regulator receives a speed signal derived from the throttle position signal and outputs an excitation signal for the traction generator which is modified by a controller in response to air availability so that engine speed and load are controlled independently of the selected throttle position, so as to limit the exhaust smoke output of the engine.