Diesel Engines

The development of diesel engines has progressed steadily over many years due to improved techniques and knowledge of machining, lubrication, metallurgy, combustion, and noise and vibration control.

Engines are available from a few kilowatts upwards at speeds of 750, 1000, and 1500 rpm for 50-Hz supplies and 900, 1200, and 1800 rpm for 60-Hz supplies. Reliability and cost reduce with increasing speed. Standby sets up to about 1.5 MVA may run at 1500 rpm provided that a long-term base load type of operation is not envisaged. Some installations may be required to continue running for long periods after normal supplies have failed (e.g., some military installations) and in such cases 1000-rpm engines should be considered above approximately 1 MW. Most diesel engines in use are of four-stroke type, but two-stroke engines may occasionally be encountered. Diesel engines are designed to run on Class A fuel to BS2869 which has a calorific value of about 42.7 MJ/kg; before running on any other fuel, advice should be obtained from the engine manufacturer. The efficiency of a modern turbocharged engine may be about 40 percent but this does not take into account any auxiliary drives or the generator losses; the overall efficiency of the generating set will be less.

The useful energy produced by the engine passes through the coupling to the generator but, depending on the arrangement of the set, it is not always possible to use all the energy to supply the intended load. Sets...