Microprocessor-based electric heat tracing controllers to improve reliability, reduce maintenance costs, and help avoid peak demands

An alternative method of electric heat tracing control using microprocessor-based electronic controllers instead of electromechanical thermostats is presented. The practical application of electronic controllers and the utilization of their specific advantages in a large Canadian petroleum refinery where ambient winter temperatures routinely reach -40°F are discussed. A Class 1, Group D, Division 2 hazardous area for electrical heat tracing control systems is assumed. Series-type mineral-insulated (MI) heat tracing cables are used for almost all electric heat tracing applications. The monitoring and control of series circuit MI heat tracing cables are discussed