Protection, metering, monitoring and control of medium voltage power systems

Traditional practices for industrial and commercial medium voltage power systems to provide protection, metering, monitoring, control, power quality analysis, disturbance recording and automation have changed. The introduction of new multifunction numerical protection relays using the processing power of the present generation of microprocessors, have very high functionality. Many functions can be integrated into one device, allowing new power system problem solving capabilities while permitting significant cost savings as compared with discrete protective relays, instruments, meters, recorders and transducers of the past. This paper describes the vast capabilities and enhancements of these devices, which are called intelligent electronic devices (IEDs) in this paper. Included are anecdotes obtained from an installation on a large industrial power system.