Temperature Controllers basically consist of two parts, which includes sensing element that responds to temperature and a switch consisting of normally open, and/or normally closed contacts. To accurately control process temperature without extensive operator involvement, a temperature control system relies upon a controller, which accepts a temperature sensor such as a thermocouple or RTD as input. The contacts operate from the temperature-sensing element. That factor to be considered when selecting a temperature controller is temperature range, type of sensing element and response time.