Multi-Engine Speed Matching
Keeping the speeds of engines working together close to one another. Since there is no communication between the channels on the GS740-3P, this matching is not automatic; the operator does it by adjusting each channel's potentiometer separately. As the matching is done through throttle lever position, the speeds can diverge again when the load changes.
The root of the problem is this: the same throttle position does not give the same speed on two different engines. The engines differ in age, fuel setting, mechanical governor characteristic and the load on them. For that reason bringing the potentiometers to the same mark does not mean equal speed.
The correct method is based on measurement. Read the speed of each engine with an independent tachometer and adjust the channels according to those readings. When the adjustment is finished the positions of the potentiometers on the cabin panel may differ; this is normal and not a sign of a fault.
The permanence of the matching is limited. When the load on one engine increases, its mechanical governor increases the fuel but the speed still drops somewhat; this is droop behaviour. A position-based system cannot see this and does not correct it. Maintaining the speed independently of load is possible only with feedback that measures engine speed; for the GS740 this falls within the scope of the optional active feedback speed holding module.
Context in which this term is used: Why is constant speed important in a generator?