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 primary differences in functionality between mechanical and electronic pressure switches are the way the applied pressure is used to operate the switch, the type 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. Each and every time the switch is actuated, a mechanical pressure switch sends a power switching signal, but will not require a voltage supply.
Ordinarily, mechanical pressure switches are simple devices which are either designed for cost-effective applications or optimised for long-term use, depending 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 usually not adjustable, thus the reset point for switching cannot be configured and is preset by factory setup.
Mechanical pressure switches 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 employed.
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 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 much more functions can be programmed in modern electronic pressure switches.
Challenge of an electronic pressure switch also offers a continuous pressure indication and shows whether the switch outputs are active or not. Last but not least, modern technologies, including the usage 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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