A New Fault-Interrupting Device for Improved Medium-Voltage System and Equipment Protection

A newly developed fault-interrupting device employs radical departures in overcurrent sensing, response, and interruption techniques. It offers a large selection of time-current characteristic curves plus high continuous current ratings combined with efficient current-limiting action in a compact, self-contained package not requiring external sensing or control power. Improved protection and coordination can be provided in a wide variety of medium-voltage circuit and equipment applications, some of which cannot be properly addressed with previously available devices. Sensing and response functions of the electronic control module and operation of the interrupting module are described. Examples are presented illustrating use of the flexible response characteristics in the solution of difficult protection and coordination applications.