SELECTIVE COORDINATION STUDY FOR PROTECTIVE DEVICES

A selective coordination study is the examination of the electrical system to ensure that protective devices are properly designed and coordinated. Protective devices are rated, selected and adjusted so that only the fault current carrying device nearest the fault opens to isolate a faulted circuit from the system. This permits the rest of the system to remain in operation, providing maximum service continuity.  If a protective device is not coordinated, a fault on a downstream device could trip the mis-coordinated upstream device, causing unnecessary outages and downtime on equipment that could still be operating.