Abstract
Flyball control of units such as are now operated in the plants of large systems may be of secondary importance for normal conditions. It is a control for large or sudden changes, a shutdown device for emergency purposes, and it effects certain conveniences in operation. It is of real use only in emergency conditions, it is entirely ineffective when a unit is on the load limit, and it is entirely ineffective when the gate position is controlled by frequency under gradual load change conditions. It comes into play in case of line troubles or when load changes are faster than the frequency control can meet.
Practically complete governing equipment can be built without a large flyball, and with probable ultimate simplification of governing equipment. It would consist of frequency control operating the gate through regulating cylinders and distributing valve, a load limit positioning device for that valve, just as is done nowadays, except that no main-relay connections would be required, no dashpot necessary, and all question of flyball drive eliminated. Emergency stop and emergency start would be obtained simply by making secondary contact at an abnormally high or low frequency point that would take the unit off the line or at least close it to “speed-no-load” condition.
It is not suggested that governors be eliminated. Many of their elements are very satisfactory. The oil-pressure systems now in use are probably the best form of speed-reducing mechanism for the purpose, reducing 600- to 1200-r.p.m. motor speed to as low as 1 r.p.m. It is suggested that they no longer be governors from a normal speed-control standpoint with its possible wide range of gate movement. They should be control mechanisms designed for the duties that they are to accomplish. The design of such controls would rapidly modify governors as they are designed today, and would also begin to modify turbine structures themselves, simplifying and cheapening them, a large portion of their cost being due to details which are not necessary or even desirable for the production of the maximum number of kilowatt-hours for a given stream flow or for a given amount of storage water.
