Chapter 12: Electrical Works

Electric Motors Use 70% of the World’s Power   ■ We impact that load 30 – 50%   ■ Savings can be as much as 20% to 30% on the overall bill   ■ Look for 1hp and above operating at least 2,000 hrs/yr 

 Basic terms related to temperature  Different scales conversion  Basic temperature measuring techniques  RTD’s and its application  Thermocouples and their applications  Comparison between RTDs and Thermocouples  State the effect on the indicated temperature for failures, open circuits, and short circuit

Electrical temperature measurement The measurement of temperature is of special importance in numerous processes, with around 45% of all required measurement points associated with temperature. Applications include smelting, chemical reactions, food processing, energy measurement, and air conditioning. The applications mentioned are so very different, as are the service requirements imposed on the temperature sensors, their principle of operation, and their technical construction. In industrial processes, the measurement point is often a long way from the indication point; this may be demanded by the process conditions, with smelting and annealing furnaces, for example, or because central data acquisition is required. Often there is a requirement for further processing of the measurements in controllers or recorders. The direct-reading thermometers familiar to us all in our everyday life are unsuitable for these applications; devices are needed that convert temperature into another form, an electrical signal. Incidentally, these electrical transducers are still referred to as thermometers, although, strictly speaking, what is meant is the transducer, comprising the sensor element and its surrounding protection fitting. In industrial electrical temperature measurement, pyrometers, resistance thermometers, and thermocouples are in common use. There are other measurement systems, such as oscillating quartz sensors and fiber-optic systems that have not yet found a wide application in the industry