Deriving the Starting Power

Engine or turbine acceleration for starting will be by one or more battery driven electric motors or, for larger diesel engines only, by compressed air.

For diesel engines an electric starting system will include one or more preengaged electric starter motors engaging with a starter ring on the flywheel rim, a battery, and a battery charger. After a few revolutions the engine reaches its firing speed and develops sufficient power to accelerate itself to rated speed. For gas turbines a pony motor is mounted on the gearbox. It may take up to a minute for the rotor to reach its self-sustaining speed, and for the turbine to accelerate itself to rated speed and to be ready to accept load.

Compressed air starting is limited to diesel engines of ratings of the order of 1 MW or above; smaller engines do not have space in the cylinder heads for the air injection valves. Selected cylinders will be fitted with air injection valves and, during starting, a rotating air distributor valve feeds compressed air to appropriate cylinders in turn. Within the engine room there will be a compressed air cylinder with drain valve and pressure gauge, an electrically driven and automatically controlled air compressor to maintain the pressure within the vessel, and for black starts a diesel driven compressor. In the United Kingdom the compressed air installation will be subject to the Pressure Systems and Transportable Gas Containers Regulations 1989 as amended by S.I. 1991/2749. The...