The new science of protective relaying in the petro-chemical industry

The petro-chemical industry is entering the 21st century with a vast array of protective relaying options ranging from the time proven electromechanical to the high speed digital, multifunction relays. While there is still an “art”, there is much more “science” involved with the design and implementation of protective relaying schemes. This paper presents the new science of protective relaying in the petro-chemical industry. A comparison is made between the time proven electromechanical and digital relays; a comparison is made between the discrete and the multifunction relays; a discussion is made on the Boolean algebra logic typically required for the multifunction relays; a discussion is made on the use of symmetrical component options available with many relays; and several multifunction relay applications are presented including rotating equipment protection, bus and feeder protection, and transformer protection