Hardware—System Components
Richard A. Panke · River Publishers eBooks · 2020
Starting from the equipment being controlled and working back to the operator&s;s console the components are sensors, actuators, microprocessor-based field panels, communication links, and a central operator station. Sensors and/or actuators are located at the equipment being controlled. Thin Film Platinum is considered the optimum sensor because of its&s; superior characteristics such as operating temperature range, interchangeability, linearity, stability, and reproducibility available through automated manufacturing conditions. Most capacitive sensors use a plastic or one micron thin polymer as the dielectric material, with a typical dielectric constant ranging from 2 to 15. Pneumatic actuators respond to controlling air pressure changes over a range of 3 to 15 psi; electric actuators respond to on/off electric signals from the controlling device. Field panels provide an interface between remote sensors and actuators. The electrical resistance of certain metals varies proportionally with temperature in a precise, consistent, repeatable manner. Resistance temperature detector made of these metals provide a measurable resistance that is proportional to temperature.