How can you decide whether to use mechanical pressure switches or electronic pressure switches in the application? Each kind 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 can be used to operate the switch, the sort of switch technology, and how the switch point could 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. 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 which are either designed for cost-effective applications or optimised for long-term use, based on how often the switching signal must be transmitted. The switches are thus designed either for a minimal application rate (very few 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.
Fide are often 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 yet another, analogue output signal proportional to the pressure. They’re either programmed at the factory to the required switch points or they feature a programming interface with integrated display and buttons.
Electronic pressure switches have integrated, programmable logic. This enables 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 many more functions could be programmed in modern electronic pressure switches.
The local display of an electronic pressure switch also offers a continuous pressure indication and shows whether the switch outputs are active or not. Finally, modern technologies, including the use of IO-Link, enable programming remotely via signal cables.
Note
Further information on mechanical pressure switches and electronic pressure switches can be found on the WIKA website.
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