Protective relays plan an integral part in the prevention of electrical hazards and to equipment and personnel. But these devices only operate during an abnormal electric power system condition, so it is difficult to determine if they are prepared to operate correctly. ANSI/NFPA70B states that the only way to assure correct operation is through a comprehensive inspection, maintenance and testing program.
NETA reports show that there is an average of 12% failure rates on protective relays tested. The typical cycle for maintenance and testing, as recommended by ANSI/NFPA70B is one to three years, but most manufacturers recommend an annual testing cycle.
Which tests to you run? There are different tests for different relays. NETA procedures include:
- Inspection for mechanical problems
- Pick up on each operating element
- Timing at three points on curve
- Target and seal-in operation
- Special tests for restraint, directional overcurrent, and other special operating elements
- Insulation tests
- Actual breaker trip test
- Peripheral and auxiliary device tests
- Function test
Ensuring you or your maintenance personnel are knowledgeable in these areas is essential to maintaining safety at your facility. The AVO Training Institute offers a number of classes including Protective Relay Maintenance courses and Microprocessor-Based Relay Testing courses to help address these needs. Contact us today to learn more.
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