How do you decide whether to use mechanical pressure switches or electronic pressure switches in the application? Each kind of pressure switch has individual advantages, but also its limitations. The main differences in functionality between mechanical and electronic pressure switches will be the way the applied pressure can be used to operate the switch, the kind of switch technology, and how the switch point can be adjusted.
Functionality of mechanical pressure switches
A mechanical pressure switch converts the pressure of a fluid into a mechanical movement that actuates the mechanical switch contact in the pressure switch. The switch has the preset or an individually, mechanically adjustable switch point. Each and every time the switch is actuated, a mechanical pressure switch sends a power switching signal, but will not need a voltage supply.
Ordinarily, mechanical pressure switches are simple devices that are either created for cost-effective applications or optimised for long-term use, depending on how usually the switching signal must be transmitted. The switches are thus designed either for a low application rate (hardly any switching cycles e.g. in safety applications) or for a higher 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 frequently have problems switching the low voltages in PLCs and modern electronics, unless expensive, gold-plated switch contacts are used.
Functionality of electronic pressure switches
An electronic pressure switch generates electronic switching signals and, very often, also an additional, analogue output signal proportional to the pressure. They’re 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 much more functions can be programmed in modern electronic pressure switches.
The neighborhood display of an electronic pressure switch also provides a continuous pressure indication and shows if the switch outputs are active or not. Finally, 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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