How can you decide whether to utilize mechanical pressure switches or electronic pressure switches in the application? Each type of pressure switch has individual advantages, but additionally its limitations. The main differences in functionality between mechanical and electronic pressure switches are the way the applied pressure is used to operate the switch, the kind of switch technology, and the way the switch point can be adjusted.
Functionality of mechanical pressure switches
A mechanical pressure switch converts the pressure of a fluid right into a mechanical movement that actuates the mechanical switch contact in the pressure switch. The switch has either a preset or an individually, mechanically adjustable switch point. Each time the switch is actuated, a mechanical pressure switch sends an electrical switching signal, but does not require a voltage supply.
Ordinarily, mechanical pressure switches are simple devices that are either designed for cost-effective applications or optimised for long-term use, depending on how usually the switching signal should be transmitted. The switches are thus designed either for a minimal application rate (hardly any switching cycles e.g. safely applications) or for a high application rate (frequent switching changes e.g. in process control). The hysteresis is normally not adjustable, thus the reset point for switching can’t be configured and is preset by factory setup.
Mechanical pressure switches can be used to switch high currents, such as pumps and drives. However, mechanical contacts often have problems switching the very low voltages in PLCs and modern electronics, unless expensive, gold-plated switch contacts are employed.
Functionality of electronic pressure switches
An electronic pressure switch generates electronic switching signals and, very often, also yet another, analogue output signal proportional to the pressure. They are either programmed at the factory to the desired switch points or they include a programming interface with integrated display and buttons.
Electronic pressure switches have integrated, programmable logic. This permits the switch points and the output signal to be adapted to the application-specific needs. Delay time, switch point, reset switch point, hysteresis or window function, normally closed or normally open, and more functions can be programmed in modern electronic pressure switches.
pressure gauge of an electronic pressure switch also provides a continuous pressure indication and shows if the switch outputs are active or not. Lastly, modern technologies, such as the use of IO-Link, enable programming remotely via signal cables.
Note
Further information on mechanical pressure switches and electronic pressure switches are available on the WIKA website.
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