Ross George is a technical sales engineer with Littelfuse. He received a Bachelor of Science degree in Electrical Engineering from the University of Saskatchewan.
Of course, reliability in harsh industrial environments has a significant impact on the overall cost of ownership when a pump/motor protective device is purchased. Besides exposure to water and electrically conductive dusts, corrosive liquids and vapors are common in many applications. For example, hydrogen sulfide (H2S) can be present in or around petrochemical fluids, which affects equipment used at the wellhead, on pipelines and in refineries. It reacts with water vapor to form sulfuric acid that eats away at electrical components.
For these and other harsh environments, protective devices designed specifically to survive in such applications should be chosen. In addition to rugged mechanical design for use on machinery with strong vibrations, the electrical circuit boards need to be conformal coated with an insulating material. When done properly, this seals the components and circuit traces so they cannot be attacked by corrosive liquids, vapors and gases.
A unit designed primarily for indoor factory applications may last only a short time in a mining or petrochemical application. However, protective devices designed for rugged environments can supply 20 or more years of reliable service in such environments. A long service life may be a compelling reason to purchase a reliable protective device, even for less demanding applications, because of its low cost of ownership.
Microprocessor-based pump/motor protection relays offer a cost-effective way to prevent catastrophic failures due to a number of fault conditions. In addition, they can protect operating and maintenance personnel by mitigating or removing shock hazards and potential arc-flash events. Those with real-time monitoring and diagnostic functions for predictive/preventative maintenance programs can reduce maintenance costs.
Pumps & Systems, November 2011