Screw terminals are a commonly used type of connection for electrical wires. They are characterized by stable holding of wiring and low voltage drop. The Screw terminal has been known and successfully used in electrical installation in its current form for several decades. Despite the unchanged concept and method of connecting wires to various electrical devices and apparatuses, it is still very popular. It is used in multi-track and single-track connection systems regardless of the voltage value. Screw terminals are also fastening and stabilizing elements for cable routes in the form of a screw carrier terminal. They are available as wire rope clamps for connecting wire ropes and elongated elements with a circular profile from a few to several dozen millimetres in diameter. As a split screw terminal they enable the attachment of cable connection sleeves in surface mounted installations.
The principle of screw-type cable clamping and holding system is appropriately shaped socket with the element that presses the cable end exposed from the insulation. The clamping is realized by direct pressure of the screw or through an intermediate plate. Screw connectors cage reliably hold the wires with a cross-section of 0.08-24 mm2, both single-wire, multi-wire and cable. In various devices and electrical equipment in which screw terminals are used, short-circuit insulation is realized through the housing made of a suitable material, usually plastic. All kinds of self-contained connectors for electroinstallation, connection, repair and reconfiguration of existing and newly constructed electrical lines, are most often made of Bakelite, PVC, polyamide, ceramics and other halogen-free materials. The use of these materials increases resistance and makes it possible to install these types of connectors in various places.
Screw terminals are generally used in locations and equipment that require a firm and stronger clamping pressure. This type of connection is provided by screw cage connectors with appropriately shaped socket for the wiring end. Protection against deformation is possible by pressing the cable from above with simultaneous support in a conical base. The forces acting on the twisted elements do not cause crushing and deformation of the wires of 0.08-24 mm2 cross-section. This connection makes it possible to fix both solid conductors of single conductor cross-section and cables made of copper or aluminium. The forces required to obtain a stable and durable connection vary from several to several dozen Nm.
The number of devices that use a screw terminal is enormous. It can be located at the end of any industrial line wiring path, hold wire ends in switchboards and electrical boxes. It works there with various types of sensors, fuses or branch strips. Due to the use of suitable quality steel, hardened carbon steel, in some cases stainless steel, brass and aluminum with galvanized or zinc plated coatings, screw terminals work in harsh environments and are corrosion resistant. Stand-alone mounting connectors are available in connection, through-hole or isolation versions for rail mounting or self-screwing in any location. In the latter version, single-track, double-track or multi-track cable connectors are available, used in low voltage lines, various electrotechnical equipment and workshop and construction tools.
Round bolted cage connectors in the shape of a sleeve enable a very secure and resistant connection which corresponds to the parameters of the cable pressing technology. Usually breakaway bolts are used here on the steel housing body, inside which the cable ends are inserted. They provide protection against deformation and a very strong connection without energy loss and sparking. The breakaway screw terminal allows the connection of different types of conductors regardless of the material they are made of. Cage screw terminals allow you to control the state of the connection, and by maintaining accuracy and adhering to the manufacturer's tightening force guidelines, you can achieve the required shock and vibration resistance of the connection.
