General information about Magnetic Switches

What is a magnetic switch?

The magnetic switch closes or opens a circuit when influenced by a magnet. The magnetic switch consists of a Reed Switch that is encapsulated in a housing of metal or plastic. A Reed Switch is a gas-filled glass tube with two contacts that overlap but are separated by a small air gap. When a magnet approaches, the contacts close rapidly to create an electrical circuit. REED technology without power consumption.

Magnetic switches can be used as contactless pulse generators for counting, standstill and speed monitors. Limit switches for doors, elevators, pneumatic cylinders, alarm systems, robots, machines, and more.

Multi-voltage

AC/DC 0 - 240 V or 0 - 50 V depending on insulation class, contact data, and installation.

Ending contact

Potential-free NC. Closes when a magnet approaches.

Change-over contact

Same function as NC, but the contact is preloaded against a non-magnetic NC contact. Switching occurs upon impact.

Opening contact

Can consist of a tongue element preloaded with a magnet that is deactivated by an external magnet or by a switching contact where only the normally closed (NC) is connected. Not a standard stock item. Bistable contact. The tongue element is preloaded by magnets with a strength halfway between on and off. Using hysteresis, the contact stops in the closed or open position. North pole closes, south pole breaks.

Temperature range

-40°C to +150°C for the sensor element. The temperature range for a complete switch depends on the cable, casing, and encapsulation. The contact distance increases slightly at sub-zero temperatures and decreases above +100°C.

Repeate accuracy

At constant external conditions, the repeatability is 0.01 mm. The temperature effect at ±20°C is ±0.05 mm. Below 0°C, the contact distance increases slightly faster per degree Celsius. Above 100°C, the contact distance decreases slightly faster per degree Celsius.

Hysteresis

The difference between on and off switching is partly dependent on mounting next to iron objects, but generally a 5-10 mm magnetic movement applies. A few special designs with extra small hysteresis are available.

Activation

The magnetic switch is activated touchlessly by means of a permanent magnet. Activation through stainless steel, brass, plastic, or other non-magnetic materials is entirely possible. Steel, iron, etc., on the other hand, shield the magnetic field, an effect that can sometimes cause problems but in some applications can be used to obtain an inverted signal or to achieve the function of a fork sensor.

The non-contact contact distance increases with increased magnetic strength. It is worth noting that steel between the poles of the magnet shorts out the magnetic field, while mounting one pole on iron gives approximately 50% stronger magnetic field.