Upgrading relay protection? — Be prepared

Abstract

There are many advantages to upgrading old electromechanical, solid-state, and first-generation numeric relays with modern numeric relays. Reliability increases because there is less direct wiring and interconnection wiring. Reliability and security of multifunction logic and settings are improved with next-generation user interface software. Remote I/O modules, remote analog/digital inputs, and thermal measurement capabilities have expanded protection, control, and monitoring. New protection and monitoring features improve power system equipment life and increase personnel safety. Maintenance costs are reduced, while internal watchdogs alert the user if the relay has a problem. Settings groups can be changed instantaneously to adapt to varying power system requirements. Modern, second-generation numeric relays offer a variety of secure communications capabilities for interfacing with Smart Grid controls, SCADA systems, and business networks. Event memory is larger for more on-board, standardized oscillographs and event reporting. Relay security is in accord with the latest NERC standards. Initially, every relay upgrade seems simple and straight forward; then come the details. Operating personnel have expectations for reading targets, resetting trips, ease of interface for settings and events, motor restarting, synch closing, etc. Regulator requirements (NERC-CIP, for example) must be implemented while maintaining smooth operations. Relay engineers must assure that operational ease is maintained with the new upgrade relay. Accurate one-line drawings and connection drawings, as well as good wiring documentation, are essential. Escutcheon plates might be necessary, or perhaps switchgear will need modification (panel cutting, new doors, relocation, etc). Also, this is an opportunity to reevaluate arc-flash hazards and possibly reduce the risks. These and other considerations are taken from actual relay replacement projects. This paper provides guidance for your next replacement or upgrade project, resulting in reducing cost, saving time, and minimizing unexpected or unplanned complications.