Cable entry
Cable entries are used to introduce or lead through electrical lines as well as corrugated hoses and pneumatic hoses in switch cabinets , junction boxes , terminal boxes , machines or inside vehicles, aircraft and ships.
The purpose is to achieve a degree of protection (tightness, contact protection, dust protection), to protect the cable from sharp metal edges or, in addition, to provide strain relief for the cables.
There are cable entries for inserting cables without plugs (e.g. rubber cable bushings as rings, grommets, perforated or slotted plates) and divisible or semi-open systems through which pre-assembled cables or cable harnesses with plugs can also be inserted. These are, for example, rubber plates divided in the area of a row of holes or broom-like barriers against dirt and lint .
Cable entries for cables without plugs
Either cable glands , grommets or cable entry plates can be used to introduce non-assembled cables and other lines, for example through machine, housing and control cabinet walls. The aim here is to seal the openings in the wall that were created for the implementation as well as possible and thus to protect the inside of a control cabinet from dirt, dust or liquids.
Cable glands and grommets are usually designed for single or a few cables; with a cable entry plate, on the other hand, a large number of individual cables with different diameters can be inserted. Depending on the model, very high packing densities or tightness values up to protection class IP66 / IP67 / IP68 can be achieved, the basis of which is the test according to DIN EN 60529: 2000-09 (VDE 0470-1).
Divisible cable entry strips for cables with plugs
Divisible cable entries have been developed for the introduction of cables to which connectors are already installed ( pre-assembled cables ). The divisibility of these systems has two major advantages. On the one hand, there is no need to dismantle and re-assemble the connector on the cables - which means that the manufacturer's guarantee for the cable is retained - and on the other hand, assembly can also be carried out later, as the cable entry is installed around the existing cables.
In most cases, these split cable entry systems consist of a rigid frame made of plastic and one or more slotted sealing elements, which are usually made of elastomer . The line is tightly enclosed by this sealing element and fixed in the hard frame. Depending on the model, this allows strain relief of the cables in accordance with DIN EN 50262 (replaced by DIN EN 62444) and tightness values up to IP66.
Cable entries with one-piece hard frame for cables with plugs
As an alternative to cable entries with a separable frame, systems with a one-piece rigid frame have also been developed for the introduction of pre-assembled cables or hoses. With these entries, the frame can be divided into several differently dimensioned passage openings with insertable partitions in a simple, T or cross shape. Suitable sealing elements can be individually pressed into these. In contrast to cable entries with a divisible frame, in which all sealing elements are pressed together for fixation, the subdivision of the frame enables individual sealing elements to be replaced when the cabling is changed. Partition walls can also be rearranged without dismantling the entire frame. The laterally slotted sealing elements for sheathing the conductors or hoses are inserted into the openings of the screwed-on frame from the inside of the housing. Their conical shape relieves strain on the outside and can be pushed out on the inside without great effort. In order to protect the cables against unintentional pushing out or manipulation, a locking frame can optionally be placed inside. Blind plugs are used to close unused frame openings.
The same system structure consisting of a one-piece frame, plug-in subdivision pieces and slotted sealing elements can also be found in prefabricated large-format flange plates through which a particularly large number of assembled conductors or hoses can be inserted. The flange plates, which are initially completely closed and sealed according to IP66, are permanently installed on the housing opening. Then, if necessary, cover segments with predetermined breaking points can be removed from the flange plate. The broken out segments give access to configurable frame openings. Such flange plates enable the serial preparation of later cable entries in switch cabinets without dust or chips getting into the interior of the housing until the final cabling and causing damage to electrical components that have already been installed.
Cable entries for less stringent protection requirements
If the interior of a housing or a machine only needs to be protected against coarse dirt and dust, cables with or without plugs can also be inserted through brush strips. This type of cable bushing is also often used in the IT industry (e.g. server cabinets in clean rooms ) or in building and stage technology (e.g. cable laying in raised floors ). Cable bushings made of foam rubber or foam are not likely to be found in durable goods.
Sizes and standards
Cable entries are available in different sizes. Common sizes are those that are congruent with those of heavy industrial connectors (10-pin, 16-pin or 24-pin) in terms of both the required cutout and the drilling pattern for the fastening points . Round cable entries usually correspond to the sizes of standard metric cutouts (M16 – M63). Since such systems are used in the most varied of applications, compliance with numerous standards is very important. These include, for example, the leak test (IP classification) according to DIN EN 60529: 2000-09 , UL approval , GL approval for shipbuilding, various approvals for use in rail vehicles or the ATEX approval, which allows installation in potentially explosive areas.
See also
Cable termination and insulator bushing
Individual evidence
- ↑ DIN EN 60529: 2000-09; VDE 0470-1: 2000-09 at Beuth-Verlag
- ↑ DIN EN 50262; VDE 0619: 2005-05 at VDE-Verlag
- ↑ DIN EN 62444 VDE 0619: 2014-05 - Standards - VDE-Verlag. In: www.vde-verlag.de. Retrieved July 27, 2015 .