In general, all kinds of switches have hysteresis switching functions, whether mechanical or electronic, whether they are used to monitor parameters such as pressure, temperature, level or flow. Hysteresis is often understood as the difference between the switch point and the reset point.
For mechanical switches, hysteresis can usually be pre-set by the manufacturer, while for electronic switches, it can also be configured by the end user.
The hysteresis function is one of the most widely used switching functions. In principle, hysteresis is necessary because if the switching point and the reset point are set to the same value, the controlled system will oscillate and therefore become unstable. Let's illustrate this with an example:
Figure 1: Pressure and switching state diagram when the switching point is equal to the reset point.
A pressure switch is used to monitor the drinking water pump. When the pressure exceeds 0At 6 MPa, this switch stops the pump by switching the output on and off. After the pump stops, if the pressure drops to 0Below 6 MPa (reset point), the switching output stops and the pump restarts.
Imagine a continuous process in which the pumps are switched on and off in quick succession (see Figure 1). This causes instability and wear and, in the long run, leads to earlier pump failure. In order to avoid such oscillations in the system, it is necessary to set the switching and resetting points that are appropriate for the process, i.e. a set hysteresis is required to stabilize the control loop (see Figure 2).
Figure 2: Diagram of pressure and switching status in the presence of hysteresis.
Mechanical switches have a pre-set hysteresis due to their design features, which are stated in the manufacturer's product specifications. Typically, the hysteresis is 10-20 from the set switching point (e.g., 0If the reset point is set at about 9 MPa, the hysteresis is 01 mpa）。
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In general, hysteresis is configurable over almost the entire measurement range in electronic switches (via external software, configuration modules, or an integrated display with control buttons). (Pressure) switches enable safety protection in a wide range of applications and are often used for redundant monitoring of critical thresholds. Due to its ease of application, the hysteresis function is the most widely used switching function in industrial applications and is the only achievable switching function for mechanical switches. The Cylinder Revolution – Hydraulic Cylinder End-of-Stroke Proximity SwitchesAt present, the "window" switch function is also common in certain applications, but only for electronic switches. The difference between the "hysteresis" and "window" switch functions is detailed here, if you have electronic pressure switch needs, Shenzhen Furongde professionals will be happy to help you choose the right pressure switch.