An Improved Design of Low-Voltage Panel-Mounted Air Circuit Breaker

Close co-operation with the Navy during the war in working out solutions for rapid improvement of pre-war standards of protection and control of low-voltage distribution circuits, gave the group that developed these circuit breakers an enviable background of experience to fit them for the program just discussed. The results of their efforts have been outlined and can be summarized by saying that industry is offered a new circuit breaker in which high inrush and momentary currents are easily handled, with an increased contact life. Accurate and proved timing elements have been provided giving a variety of desired time-current characteristics. A wider application on motor and other repetitive duty high inrush current circuits is assured by longer contact and mechanism life and accurate delayed tripping obtained with the fluid displacement timing elements. Dependable selective operation can be obtained without the additional expense of current transformers and relays. Contacts and coils which will stand the high momentary currents, while tripping is delayed with an accurate mechanical timing device, make possible dependable selective operation, so unquestionably proved on the Navy's major ships.