This chapter outlines a program for testing and commissioning of protective
and overcurrent relays and instrument transformers used in switchgear and/
or standalone applications. The frequency of testing of these devices may be
dependent upon many factors; however, an annual schedule of inspection
and maintenance is recommended for electromechanical and induction
relays; and inspection and testing of solid-state and microprocessor relays
when trouble is indicated or upon unanticipated operation of these relays.
Before a successful maintenance and inspection program can be implemented,
it is essential that the personnel performing or evaluating inspection
and maintenance should be thoroughly familiar with the types of
protective relays, devices, and auxiliary equipment. Therefore, in this section
a brief overview of protective and overcurrent relays, and instrument transformers
is given for the reader to become familiar with the system equipment.
The maintenance and testing of electromechanical and induction
relays involves inspection, mechanical adjustment, and electrical tests.
Similarly, the maintenance and testing of solid-state and microprocessor
relays involves inspection and self-diagnostics and tests. Since the protective
equipment plays such an important role for the safety of personnel and
property, they should be given special attention. Moreover, since these
devices operate during abnormal conditions on the power system, the only
way to assure correct operation is by a comprehensive inspection, maintenance,
and testing program.