Tamar Designs
SPEED CONTROL
A turbine must have some form of governor to control the speed if it is to produce a stable alternating current in standalone schemes.
Speed of units of less than 150 kW is normally controlled by applying an electrical load on the alternator that balances the power output of the turbine. This is done with a current controlling device and a set of water heaters.
The pictorial diagram, (below), shows the principleused on the small units, where surplus electrical energy is used to provide hot water. Alternatively, if preferred, a set of air heaters could be used, for such purposes as drying some agricultural product. Normally, the hot water system is the most convenient and four or five immersion type water heaters are used.
 The governor is a solid state electronic device, with no moving parts. It is fitted with a multi pin connector for easy replacement and is mounted in a steel box on the switchboards, together with the normal circuit breakers and switches, (left).
The governing equipment is situated at the receiving end of the transmission line, which is more convenient than having it by the turbine. It also has the advantage of keeping the transmission line on a constant load so that voltage fluctuations are minimised.
Units of over 150 kw normally use an electronically controlled governor that operates appropriate water flow devices that vary depending on turbine type and operating parameters. Impulse turbines use the governor to control spear valves and deflectors, whilst reaction turbines control the speed by moving guide vanes.
| 
