Physical control devices are components for controlling electrical consumers depending on outdoor light, pressure, fill level, etc. Mounting tools and other additional products are available as accessories. Pressure switches are mechanical or electronic switches that are activated by pressure changes in a gaseous or liquid medium, such as air or hydraulic fluid. They are used, for example, to switch pumps, valves or compressors s that the pressure or fill level of the medium in a pressurised storage tank does not exceed the upper value or fall below the lower value. The mechanical pressure switches of series DSP are suitable, depending on the design, for switching single to three-phase motors for pumps. The increasing pressure of the medium to be monitored presses against a membrane of the pressure switch. As soon as the pressure exceeds the upper switching point, the NC contact opens and switches off the connected motor. If the pressure drops below the lower switching point, the contact goes back to its idle position and the motor starts. The pressure switches allow both the switch-off pressure and pressure difference to be set. The pressure connection, pressure sensor element, switching mechanism and electrical connections are mounted on a high-quality plastic base plate. The cover protects the switch from environmental influences.