A magnetic switch is an electrical switch that closes or opens contacts in a magnetic field. The switch remains on as long as a strong magnetic field is present and opens when the field is removed. Magnetic switches include reed switches, Hall sensors, and electromechanical relays. The simplest switches include magnetic window switches and door magnetic switches.
Types of Magnetic Switches
Reed switches
Reed switches are highly adjustable and sensitive to magnetic fields. In addition, they are quite cheap. Unlike switching electromagnetic devices, the reed switch has contacts that are located in a sealed flask, from which air is pumped out or is filled with an inert gas. This design eliminates the process of surface corrosion.
Hall effect switches
A Hall sensor, or rather a position sensor based on the Hall effect, is a device that detects the presence of a magnetic field and measures its strength. The direction of deflection of electrons in a conductor is perpendicular to the direction of the magnetic field. On different sides of the plate, the electron density will be different, which will cause a potential difference. It is fixed by the Hall sensor.
Normally open magnetic switch consists of flat contact plates hermetically sealed in a glass tube filled with an inert gas (reed switch). When a permanent magnet approaches, the contact plates begin to attract each other and close. When the permanent magnet is removed, the contact plates instantly demagnetize and return to their original position.
The air gap between the contact plates is only 0.2 … 0.3 mm, so the moving mass for closing and opening is extremely small. Therefore, magnetic switches are almost inertial and can be considered “pseudo-electronic components”.
These economical and easy-to-install magnetic switches are great for process automation and can also be used as position indicators for sliders, dampers, and valves.
The reliability of these compact switches is ensured by the long service life of their electrical parts. Because magnetic switches are mostly made up of just one component, they are safe to operate. Additionally, special versions are available for extreme temperatures -200 … +200 °C.
Peculiarities
Magnetic switches function reliably under extreme environmental conditions such as dirt, humidity, gas, dust, chips, etc.
Stable switching point, switching point reproducibility error 0.01 mm.
The reed switch can be triggered when exposed to various directions.
Mounting in any position.
Operation without a power supply, bistable versions save on the number of signals and are particularly suitable for large strokes.
Application
A pulse generator for pulse counters is used for rotating parts, piston stroke measurements, and other applications.
Dynamic and stationary control of machine tools.
Vibration amplitude control of centrifuges.
Management of metal-cutting, as well as weaving and printing machines.
Scales, resonant conveyors, and resonant screens.
