A New 3kVA Standby Diesel Generating Set for use in Small Remote Telephone Exchanges

In the U.K. small rural telephone exchanges have invariably derived their energy from a rectified a.c. electricity supply system which is rated at a nominal 240V 50Hz single phase. The standby source of supply has been from a nominal 50V battery which could keep the equipment fully operational for at least 24 hours. The increasing use of the electronic switching systems has meant a more constant load pattern, even when the equipment is in a near-quiescent condition, and this, coupled with the need in some cases to provide a longer period of reserve power capacity, has resulted in the demand in the U.K. for a small, compact, low cost generating plant of 3kVA capacity. This paper shows how a high speed, 3000rpm diesel engine was adapted to function as part of a permanently installed generating set and goes on to explain the design features of the whole plant and its associated control system.