Proximity Switch – Magnetic Switch
Proximity switches – magnetic switches for precise and safe operations
Contactless proximity switches are indispensable within the industrial sector. Compared with mechanical switches, they offer the best conditions – their contactless functionality ensures that there is no wear and tear during operation and thus in turn the switch has a long service life. High switching frequencies and accuracy ensure the accuracy of the switch. The compact design provides guaranteed protection against dust, moisture and vibrations.
The use of sensors as providers of information for control units is an important requirement in every automated process. The sensors provide signals about positions, locations and fill levels and act as the pulser for counting tasks and for measuring speed.
Individual proximity switches and stop sensors?
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Examples of proximity switch applications
In the industrial sector, autoclaves are used in door systems, where the correct locking position must be in place before pressure can be built up inside the device. For this purpose, up to four magnetic switches may be used. These detect whether the correct locking mechanism is in place and thus create a redundant security system.
Reed Electronics has many years of experience in the area of autoclave locking systems and extensive knowledge of suitable magnets and sensors to meet every need – including for indoor temperatures of up to 140° C. The contactless magnetic switches are designed to be resistant and long-lasting and keep maintenance and wear and tear to a minimum.
Conveyor belts
Contactless sensors can be used to detect positions and objects – and are frequently used for conveyor belts.
Magnetic switches and magnets detect the current situation on a band or an exact position to ensure that objects are positioned in a specific way. These may be containers that need to be filled, which must always be kept in a specified position.
In another area of use, proximity switches detect the presence or absence of mechanical parts with integrated magnets. Magnetic switches may be integrated into different casing shapes and materials, meaning that the sensor can be adapted to the application at hand.
How does a proximity switch work? – Basics of magnetic sensor technology
A proximity switch detects objects without physical contact. While optical sensors operate with light beams, a magnetic proximity switch uses an internal magnet system or a so-called reed contact. When a permanent magnet or magnetic field approaches, the switching state is triggered. This process is contactless and therefore wear-free.
Key advantages of this technology:
- Wear-free operation: No mechanical wear due to contactless switching.
- High switching frequencies: Ideal for smooth processes.
- Precise switching points: Defined activation at an exact distance.
- Robust design: Resistant to dust, moisture, vibrations, and temperature fluctuations.
Structure and working principle of the magnetic proximity switch
In many cases, magnetic proximity switches are based on a reed switch enclosed in a hermetically sealed glass housing. Two ferromagnetic reeds act as switch contacts. When an external magnet approaches, the magnetic field pulls the reeds together, closing the circuit smoothly and without contact. When the magnetic field is removed, the reeds separate again.
Thanks to its compact and sealed design, this proximity switch sensor is optimally protected against dirt and liquids. Additionally, the switching element can be integrated into various housing shapes, allowing for customized adaptations to specific installation requirements. Depending on the application, a changeover switch (SPDT) can also be used to enable additional switching functions.
Additional Applications: Alarm Systems, Position Monitoring & More
Door Contacts and Alarm Systems
Magnetic proximity switches secure doors in alarm systems, robotic cells, or windows. They detect openings early and reliably report break-in attempts or maintenance access automatically.
Position Monitoring in Pneumatics and the Automation Industry
In pneumatic cylinders, proximity switches detect end positions without contact by sensing piston magnets. Robotic applications also benefit from enhanced safety through reliable position monitoring.
Control of Air Conditioning Systems
In this field, resistance to wear provides crucial advantages. Magnetic proximity switches reliably detect positions in air conditioning systems and enable precise control of moving components, such as air flaps or valves. Their contactless functionality ensures long-term stable performance, even with frequent switching cycles and in demanding environments with temperature fluctuations or humidity.
Individual Consultation by Reed Electronics
In many cases, customized sensor solutions are required. Reed Electronics offers comprehensive consultation to help customers determine the ideal combination of magnet and switch. The following factors play a role in the selection process:
- Temperature range: -20°C to 200°C (depending on material)
- Environmental conditions: Humidity, dust, chemicals, pressure
- Mechanical requirements: Housing material, dimensions
- Mounting type: Threaded, with housing, pluggable, or custom-made
- Switching power and voltage supply: A typical reed switch has a maximum switching power of 10 W and a maximum switching voltage of 25 V AC or 50 V DC, optionally up to 230 V AC.
- Safety aspects: Redundancy, wear resistance
- Explosive environments: Special ATEX-certified magnetic switches for hazardous areas
Reed switches are sensitive to vibrations and are therefore not suitable for highly vibrating environments. However, they can be easily integrated into assemblies and are available in various designs (threaded, housed, pluggable, or customized). The switching function can be configured as normally open (NO), normally closed (NC), or changeover (CO).
FAQs – Frequently Asked Questions About Proximity Switches
How do contactless proximity switches differ from mechanical switches?
Contactless switches operate without mechanical contact points, making them virtually wear-free. This reduces maintenance costs and significantly extends service life.
Why is the switching accuracy high?
A magnetic proximity sensor precisely responds to defined magnetic fields, ensuring accurate switching points for door positions or object detection.
What switching power and voltage options are available?
Reed switches can be used in various voltage ranges. The maximum switching power is 10 W, with a maximum switching voltage of 25 V AC or 50 V DC (optionally 230 V AC). The available temperature range depends on the material used and varies between -20°C and 200°C.
