Chokes for limit switches
Glands for limit switches are a group of accessories that are used to protect the connection. They protect both the cable and the device itself by sealing the connection between the housing and the switch power cable.
Chokes for limit switches - types and application
Limit switches are devices that are most often used in industrial installations. Their task is to cooperate with the control of machines. Limit switches inform the system about a specific machine operation state, thus triggering its appropriate reactions. I also play the role of safety switches, for example, preventing the operator from being allowed to operate parts of the equipment or protecting the production process against unjustified downtime.
Limit switches often operate in harsh environmental conditions, e.g. high dust or humidity, therefore their mechanism requires not only a properly tight and appropriate housing made of appropriate materials, but also protection at the point of cable entry to ensure the durability of the connection. For this purpose, glands are used, which constitute a barrier to harmful substances, and also strengthen the cables in a place particularly exposed to their damage.
Gland, cable gland or cable gland?
The correct name of a small but important piece of security for a connection is a gland . The terms cable gland, gland or choke are also used interchangeably, although the last of them is sometimes confusing due to the fact that electric chokes are inductors that have nothing to do with glands. Nevertheless, all the terms mentioned are commonly used, especially in trade.
Electric chokes - not only for limit switches
Electric glands allow a wire or cable to pass through walls or equipment enclosures. Stuffing boxes have different forms depending on the specific place of application. They are available as single elements or complete units, e.g. in the form of frames with several or even several dozen sealed holes. Such bushings are used in electrical or control switchgears, as well as RACK cabinets, where all cables connected to the devices supplied from a given cabinet are led out, for example, in the lower part of the housing, and then to the cable tray system.
Sometimes bundled or single cables are routed through the wall using a short PVC conduit for electrical applications. Ceiling culverts are used similarly. Another group of bushings are single glands used in the case of electrical devices powered by one wire, as is the case with glands for limit switches .
What is the function of stuffing boxes?
The function of the gland, especially in the case of electrical equipment, is to partially stiffen a section of a cable or wire. Thanks to this procedure, the cable is less exposed to mechanical damage caused by material fatigue caused by frequent bending of the cable. Additionally, the cable glands provide protection against cutting the insulation with sharp edges of the device housing (especially if it is made of thin sheet metal), and also against accidental pulling the cable out of the device housing.
Stuffing boxes can also seal the connection itself, thus protecting the inside of the device and electrical connections against the ingress of solid bodies, dust or liquids, and also constitute a pressure barrier, e.g. in vacuum devices.
Limit switches - types of glands
Chokes for the limit switches are elements made of plastic or rubber. Usually, each manufacturer offers bushings dedicated to a specific group of switches - they are shaped to the housing and are usually characterized by a simple method of assembly, sometimes without the use of additional tools. The most common are rigid or stiffened plastic glands or soft and flexible rubber glands.