Wiring system
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In electrical engineering, a wiring system is a system that represents an orderly structure of components such as contactors , fuses , relays , programmable logic controllers , frequency converters , etc. and the associated laying of wires and electrical lines . In the conventional sense, this is a mounting plate with cable ducts for routing cables and other aids, for example top-hat rails, as well as mounting options for the controls.
Contemporary layout of control cabinet wiring
Wiring system
The usage of the language does not allow a clear explanation or assignment of the term "wiring system". Some manufacturers of "systems" that are used in control cabinet construction use the term itself without defining the complexity more precisely. Friedrich Lütze (1923-2014) can be seen as the inventor of a wiring system, see patent " DE 2042942 B " from 1970 or " DE 7610960 U1 " from 1979.
Definition (s)
Before the word “wiring system” is explained in more detail, the term wiring should be clarified.
“Wiring” is understood to mean everything that is required on the electrical side within a control cabinet , within a distribution cabinet or the like for control or regulation of any kind. The size of the closet does not matter. It is primarily important that according to the standard EN 60204 (old VDE 0113) more than two components are connected with wires or lines. Components are switches, buttons, contactors, relays, PLCs, frequency converters, terminals etc. that are required for control or regulation. In the simplest case, these are only terminals for signal distribution. The design engineer or the switchgear builder defines the routing and layout of the cables in accordance with their prescribed standards . All technical terms as used in the standards, for example "electrical installation duct to be opened" (EN 60204, terms, 3.5) are only partially relevant for the meaning of the description of the wiring system. Which is not to say that the use of a "wiring system" invalidates or can be used to override standards.
Wiring also includes everything that has to do with the mechanical structure of the components and the necessary cabling / wiring of the same. Whether the wiring is done with single wires or stranded wires , with cables or data lines , etc., is up to the user and the necessity of the specifications of the component suppliers. The cable routing must also be viewed from the point of view of mechanical activity, because bundling cables, fastening them, laying them with the correct radius are only conditionally electrical properties. The wiring in a control cabinet has proven to be very practical over the past 40 years and has more or less become the standard to be observed worldwide. The switchgear in the area of building automation maintains, partly based on the history, a simpler cable routing without cable duct . Note: In the field of building automation, too, more and more intelligent control technology is being used, so that the need for more flexible wiring is increasing here too. Various buildings, equipped with control cabinets and complex control technology for air conditioning and ventilation systems, prove this (airports, department stores, etc.).
The wiring systems of the providers established on the market today look a little different: The cable ducts are no longer necessary, and the mechanical structure for the components and the cable routing is modular. It fulfills all necessary framework conditions on the part of the standards and all framework conditions on the part of the manufacturer's specifications for the construction of their components. The wiring system is used to simplify and perhaps also to standardize the essential work for and in a switch cabinet / switch box. The wiring system has additional, more significant advantages and will be explained in more detail, as there is an increase in space for the components, since the cable routing predominantly runs behind it, and a better temperature balance, since hot spots are almost impossible. The wiring system itself should, but does not have to, be neutral to the control cabinet housing.
Terms, explanations for the wiring system
Wiring system / wiring frame
The wiring system is understood to mean the system for wiring with a wiring frame. There are terminological overlaps here that have not yet been specified anywhere. The wiring frame is the actual product that is being worked with. Profiles for the construction of a frame are details of the mechanical mounting of the components, the routing of the wiring and ultimately the construction of the wiring frame. To date, these profiles have mainly been made of aluminum. This material has two important properties: good conductivity and easy to manufacture and modify as a continuously cast profile. Note: Siemens once made designs made of sheet metal and Klöckner-Möller, now EATON, had a system made of plastic profiles.
Comb profiles
The comb profiles are used to fix the individual wires and cables in the area of the component connections. Depending on the manufacturer, the comb profiles are available in different lengths and for different conductor cross-sections. The comb profile should (te) be designed in such a way that, on the one hand, different conductor cross-sections are securely held, but on the other hand, the necessary "clamping" between the comb teeth does not damage the cable insulation. The only known disadvantage of the comb profiles: With thicker lines (> 10 mm²) bending forces occur that cannot be absorbed by the known plastics used without additional aids.
Bars / assembly or horizontal profiles
The components are built up using the horizontal profiles. Depending on the components to be installed, the horizontal profiles are designed either with an integrated top-hat rail (top-hat rail shape according to DIN 60715; TH35-7,5 and TH35-15) or with a smooth surface for free assembly. These two surfaces correspond to the standard applications in building with a mounting board.
Vertical profiles
By means of the vertical profiles, the horizontal profiles are connected to form a stable assembly frame that matches the respective housing.
hanger
The brackets are used to gain space for the rear line routing. In addition, the brackets on the left and right in the vertical form the rear cable duct. So far, the standard dimensions for the bracket height have been 50, 80 and 120 mm. Of course, other dimensions can also be implemented - both with brackets and spacers.
Fundamental difference between the mounting board and the wiring system
When installing on a mounting board, everything is done on one level. When using a wiring system, planning and wiring can be carried out in at least two levels. The wiring in a wiring system is mainly behind the components.
All components, including cable ducts and top-hat rails, are attached to the plate according to the choice and specifications of the component manufacturer. Then the construction and the wiring take place.
The profiles for building the components are selected based on the size of the components. The sequence is defined and the distance between the mounting bars and the mounting rails is determined based on the expected line volume. The assembly and wiring are carried out with the existing wiring system / wiring frame in the electrical workshop.
Work steps for the control cabinet
Regardless of which machine or system is to be operated, the control cabinet is usually defined in terms of components and functionalities in the electrical construction and manufactured in the control cabinet construction. The common practice was / is that the machine builder, system planner is limited to determining the necessary functions and the necessary components and the rest is done in the control cabinet. In plain language: The control cabinet is planned and built around the "necessity"; not necessarily up-to-date in relation to the required resource “space”. Today, more than 95% of the control cabinet is built using a mounting panel. Top-hat rails and cable ducts (see above: installation duct to be opened) are then attached to these so that the structure and the wiring can be carried out. Other construction aids complement the whole. The overall structure is based on a wide variety of aspects that should not be explained in more detail. After the "mechanical" construction, the wiring takes place, the cabling according to Circuit diagram or the required specifications from the component manufacturer.
Components considerations
In contrast to the use of a mounting board, when using a wiring system, the type of construction and the dimensions of the components must be brought to the fore. Based on the components to be assembled, the appropriate profiles, suitable in terms of width and type of construction, are selected and then assembled into a wiring frame (the latter is usually done by the supplier). Basic structure of a wiring frame: one vertical profile each (length according to the cabinet height) on the right and left; The brackets (theoretically the vertical rear cable ducts) are then screwed onto these vertical profiles. The horizontal profiles are then screwed onto a pair of brackets. Profiles with integrated top-hat rails and with a smooth surface are available for the basic structure (see Profiles above). Different web widths based on the different structural dimensions of the components enable optimal space utilization for the components.
Wiring considerations
The wiring on a wiring frame / with a wiring system is carried out in the same way as wiring with cable ducts: horizontally and vertically, at an almost right angle, and very important: From the front (through the gaps between the horizontal profiles and a sufficient distance on the sides, every line can be routed without problems be shifted "backwards"). The safe cable routing takes place in the area of the components via comb profiles into which the individual wires / cables are locked. The rear brackets behind the horizontal profiles ensure that the cables are routed vertically.
Advantages of a modular wiring system
Space gain
If the assembly series can be optimally aligned to the components, if cable ducts with their space requirements are almost eliminated and if the distance between the components or the assembly series can then be reduced, the result is, based on the width and height of the control cabinet housing, based on the equivalent mounting panel , more space for components.
Temperature balance
As there are no cable ducts between the control components, the "circulating air" can flow around the individual components more easily in the first stage and thus more easily remove the heat loss; the formation of hot spots is reduced. The subject of temperature on components is important insofar as too high a temperature due to the heat loss (> 42 ° C) should be avoided as far as possible. The better flow behavior around the components can demonstrably extend the service life of the components and less additional energy can be used for possible cooling.
Web links
- Wiring system from the manufacturer Lütze
- Wiring system from the manufacturer Promet
- Wiring system from the manufacturer Satie
Individual evidence
- ↑ Patent DE2042942 : Cable duct and mounting rail kit. Registered on August 29, 1970 , published March 2, 1972 , inventor: Friedrich Lütze.
- ↑ Utility model DE7610960U1 : quick assembly base . Registered on April 8, 1976 , published October 31, 1979 , inventor: Friedrich Lütze.