Area of application
Alongside mechanically operated limit switches, magnetic reed switches are enjoying an increase in importance. They are often used to complement limit switches with plungers, rollers and swivel levers and are considered an important link to non-contact and contactless limit switches. In lift construction, magnetic reed switches are used to generate zone signals, levelling signals, delay points and to generally determine positions. These are used preferably where mechanically actuated limit switches no longer function satisfactorily due to unfavourable operating conditions such as high or low startup speeds, high switching frequencies, strong dust or dirt influence, high humidity, or large fluctuations in operation interval, or where noise emission must be avoided.
The magnetic reed switches consist of two units, the switch and the actuating magnet. The contacts of the switch are protected from dust, humidity and corrosion through the enclosed glass tube. Magnetic reed switches thus have an extraordinarily high contact reliability. The enclosures are made of thermoplastic; the versions for the different applications are rectangular, cylindrical or flat. Magnetic reed switches are fitted with mounting holes, threaded bolts, screwed flanges or on C-rails. They are provided with a central fixing screw or slotted holes for the adjustment. BN 260 is highly insensitive to transverse misalignment.
Design and operating principle
There are normally open (NO), normally closed (NC) and bistable contacts; with some types, the switching conditions are indicated by LED. The switches are actuated with actuating magnets with and without enclosure. Depending on the type of switch, a specific actuating magnet for lateral or front actuation as well as different actuating distances can be chosen. In order to avoid malfunctions, the actuating planes are provided with symbols. Because of their bias voltage, bistable contacts are the most sensitive switches. Depending on the application, magnetic reed switches with pre-wired cable, cable entry or connectors are available. Protection class is up to IP 67.