8–4 889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUALGENERAL MAINTENANCE CHAPTER 8: MAINTENANCEGeneral MaintenanceThe 889 requires minimal maintenance. As a microprocessor-based relay, itscharacteristics do not change over time. The expected service life of a 889 is 20 yearswhen the environment and electrical conditions are within stated specifications.While the 889 performs continual self-tests, it is recommended that maintenance bescheduled with other system maintenance. This maintenance can involve in-service, out-of-service, or unscheduled maintenance.In-service Maintenance1. Visual verification of the analog values integrity, such as voltage and current (incomparison to other devices on the corresponding system).2. Visual verification of active alarms, relay display messages, and LED indications.3. Visual inspection for any damage, corrosion, dust, or loose wires.4. Event recorder file download with further events analysis.Out-of-service Maintenance1. Check wiring connections for firmness.2. Analog values (currents, voltages, RTDs, analog inputs) injection test and meteringaccuracy verification. Calibrated test equipment is required.3. Protection elements setting verification (analog values injection or visual verificationof setting file entries against relay settings schedule).4. Contact inputs and outputs verification. This test can be conducted by direct changeof state forcing or as part of the system functional testing.5. Visual inspection for any damage, corrosion, or dust.6. Event recorder file download with further events analysis.FASTPATH:To avoid deterioration of electrolytic capacitors, power up units that are stored in a de-energized state once per year, for one hour continuously.Unscheduled Maintenance (System Interruption)• View the event recorder and oscillography for correct operation of inputs, outputs,and elements.
