A properly co-ordinated protection system is vital to ensure that an electricity distribution network can operate within preset requirements for safety for individual items of equipment, staff and public, and the network overall. Suitable and reliable equipment should be installed on all circuits and electrical equipment and to do this, protective relays are used to initiate the isolation of faulted sections of a network in order to maintain supplies elsewhere on the system. This then leads to an improved electricity service with better continuity and quality of supply.Written by two practising electrical engineers, this second edition of the best selling Protection of Electricity Distribution Networks (IEE, 1998) offers both practical and theoretical coverage of the technologies, from the classical electromechanical relays to the new numerical types which protect equipment on networks and in electrical plant.