TRANSIENT LIGHTNING PROTECTION FOR WATER/WASTEWATER TREATMENT PLANTS

This paper will discuss methods used for successfully protecting power distribution systems, field mounted instrumentation and control systems from the damaging effects of lightning strikes.Wastewater plants have several physical locations that are at high risk for lightning strikes. Electric and electronic equipment in these areas is prone to malfunction because of electrical surges present on the distribution system. These areas include pump lift stations, RTUs (remote terminal units), elevated tanks, radio antennas. The equipment most at risk includes variable speed motor drives, process transmitters, communication equipment, and DCS or PLC controllers.Using a case history example, we will explore the need to develop a systematic approach to lightning protection as suggested by the IEEE (Institute of Electrical and Electronic Engineers). Special consideration will be placed on IEEE Category C locations that have the potential for direct lightning strikes and which represent the biggest concern for wastewater facilities. Category C locations are outdoors or have electrical wires entering from the outside. The intent of this paper is to introduce the topic of surge suppression at water/wastewater plants and to inform the user of new technologies available to combat surges.