Fault protection on shipboard A-C power-distribution systems

THE growth in the use of electrically driven auxiliaries on shipboard has produced very large increases in the installed generating capacity. This fact together with the necessity for maintaining a high degree of reliability and continuity of service in shipboard powerdistribution systems has emphasized the importance of providing adequate fault protection. Such protection is concerned primarily with the automatic isolation of a fault with minimum damage and with minimum disturbance to the remainder of the system. It is the purpose of this paper to develop some of the fundamental considerations in fault protection on shipboard and to establish the basic principles and methods for the selection and arrangement of the various protective devices to achieve a complete and co-ordinated protective system. The discussion will be restricted to low-voltage (600 volts or less) a-c systems although many of the principles are also equally applicable to d-c systems.