Kradex DIN rail-mounted enclosures


Universal and modular solutions compliant with international standards.

  • A few words about DIN rails and modules
  • Universal modular DIN rail enclosures
  • ZD series of enclosures from Kradex
    • Enclosures (bodies)
    • Front blank covers and filters
    • Connector and terminal covers
    • Multi-level PCB system

The DIN rail, whose common name is derived from Deutsches Institut für Normung, was developed in Germany, in the 1950s. It soon became the international standard for fixing components of electrical systems in households, industrial plants, power engineering and even in transport. Standardized fuses are popular, but also a variety of other control, power, etc. devices enclosed in modular, easy-to-install enclosures. No wonder we are also seeing increased interest in universal DIN rail enclosures. These allow for the manufacture (as well as construction of smaller numbers) of devices that can be easily installed in control cabinets or switchboards.

A few words about DIN rails and modules

First of all, let’s point out that the mounting component called the DIN rail is just one of many standards defined by the German Standards Institute, specifically: DIN 46277-3. The same dimensions are also defined by European (EN 50022) and British (BS 5584) regulations. Such a rail is also sometimes called “type O”, “type Ω” or (because of its hat-like cross-section): top hat rail or Hutschiene (German). This standard is also present in North America (as “TH35”, formerly “TS35”), although in this region it is used mainly in the automation and power sectors. DIN rails (let us stay with this popular term) have several advantages. First of all, they are simple and inexpensive to manufacture, while offering a convenient method of mounting/dismantling modular components of electrical systems. It also features neat, easy-to-remember dimensions (Fig. 1).



Fig. 1. Dimensions of the most popular
DIN rail variant.Author of the image: Markus Kuhn.

DIN rails are associated with standardized modules and switchboards, cabinets, boxes and switches. They are designed in such a way that many types of devices (transmitters, controllers, power supplies, and especially fuses) can be enclosed in a strictly-defined enclosure format and in a way that is safe for the user/operator (live components remain hidden behind the panel). The width of a single module on a DIN rail is 17.5mm. For example: commonly used household overcurrent circuit breakers require one slot, while residual current circuit breakers are about 35mm wide (~2×17.5mm) or about 72mm wide in the case of three-phase variants (~4×17.5mm). Usually (though there are exceptions) the width is related to the number of wires connected to the unit: two screw terminals per module. Single-slot units are also used to define the capacity of switchboards and control cabinets. A 2×12 cabinet will accommodate 24 modules, 12 on each of 2 rails.

Universal modular DIN rail enclosures

Despite the fact that the range o products offered by manufacturers of electrical/electronic devices in the field of modular equipment is extremely wide – in the industrial automation, it is quite often needed to build a customized device, performing an unusual function, adapted to the specific requirements of the system. It would be best if such a structure could be placed on a regular DIN rail, where it would be easily connected with other system components. This is whereuniversal enclosures, which have been adapted for installation in control cabinets, come to the rescue. This is also a great solution for electronics manufacturers who don’t have the facilities to mould plastics. Modular enclosures will also be appreciated by hobbyists experimenting with home automation.

The TME catalogue includes several solutions in this field, first of all universal designs by Kradex. These enclosures are durable, made with precision and – as usual in case of this manufacturer – characterized by an excellent quality-to-price ratio. At the same time, they offer to the designer a wide choice in terms of the layout of connections and a maximum space for circuits/components – which will be very significant in the case of devices using, for example, transformers or high-current relays. The products we describe below, grouped into the ZD series, are compatible with each other and allow for flexible configuration.

ZD series of enclosures from Kradex

The ZD series solutions feature a modular design, which makes it easy to adapt the enclosure to the specific application. This flexible system, which is described in the video below, offers a wide range of possibilities for designers and mounters, allowing the use of various types of connectors, components, non-standard and standard solutions.

ZD series


Kradex range of products includes various sizes of both enclosures and compatible PCBs.

The individual components of the ZD series system, which includes enclosures, covers (filters), blank covers and even PCBs used for the construction of DIN rail-mounted devices, are described below. You can also see all the products and check their parameters in our catalogue:

Enclosures (bodies)

The basic component of the ZD series are bodies, i.e. the basic part of the enclosure, which includes other components that will be placed there. Kradex has prepared 6 sizes of these products –with 5, 6, 8, 9, 10 and 12 modules. They are made of light grey ABS polymer with the UL94V-0 flammability rating (self-extinguishing within 10 seconds). Inside, we can find sleeves for mounting PCB circuits. The enclosures are mounted on a DIN rail by means of three plastic hooks with snaps, which properly stabilize the component in the distribution board.


Main component of a 10-module enclosure.

Front blank covers and filters

The front panel of the enclosure must be covered to block access to the wires connected to the power grid (this is required mainly for safety reasons). If the constructed device does not contain signal elements or buttons, the best solution will be to use a front blank cover made of the same material as the rest of the enclosure. It can also be milled or manufactured in another way, if there is a need to bring out a panel element (e.g. a switch) – however it is recommended that they are fixed inside the enclosure, which will prevent accidental removal of the blank cover. There are also applications containing indicator lights and even displays that should be visible to the user.

For such projects, Kradex has provided filters – blank covers made of transparent materials. They come in two variants: transparent and transparent-red. The latter type not only transmits visible light of the appropriate wavelength (emitted by optoelectronic LED components such as segmented and matrix displays and diodes), but it is also completely transparent to infrared radiation. Thank to this, this type o enclosures can be used to construct devices controlled wirelessly, using IR transmitters and receivers. Such a solution is often used in measuring devices which display the monitored/counted value and allow for its wireless reading.


Red (transparent) filter for mounting on the enclosure panel.

Connector and terminal covers


The holes in the cover are spaced at 5.08mm.

Kradex enclosures offer enough space for a device placed inside to support dozens of wires attached by terminal blocks. Although only some applications will require as many connections, they may need to support different types of connectors. That is why Kradex manufactures four different types of covers. The first type is full blank covers, which completely cover the cut-outs at the top or bottom of the enclosure. Another solution will be components that cover only the front of the opening – they create a gap that, during installation, will allow access to e.g. an Ethernet socket mounted inside the enclosure, or will allow a ribbon cable plugged into an IDC socket to be led out of the enclosure.

The third variant includes covers with an oblong hole, leaving space for plugging in cables – this solution is provided for circuits using an unusual for ZD series terminal spacing. That brings us to the standard adapted by Kradex, i.e. terminal blocks of 5.08mm. If the designer decides to use such a solution, it will be possible to use the fourth type of cover: with factory-made holes for a screwdriver pin. The distributor also offers triple blank covers to hide cable glands that are not in use.


Example of a terminal block with 5.08mm spacing – fully compatible with the ZD series.

Multi-level PCB system

For designs that will not be manufactured using a specially designed PCB, Kradex has prepareda group of universal PCBs with THT holes spaced at 2.54mm (0.1″) and mounting screw holes. These are mainly PCBs of three levels. A0: the base laminate with the largest space, intended as a base for the main circuit of the device, a place for mounting its largest components (e.g. relays) – it contains fields for soldering terminal blocks. B0: the middle circuit with components that should remain at a certain distance from the paths connected to the power supply (e.g. microcontrollers). C0: front PCB replacing the front cover or filter (displays, buttons and other interface components). In addition, the manufacturer provides a selection of vertically mounted (at right angles to the A0 base) PCBs – both longitudinal (D0, E0) and transverse (U2). They can act as connectors between the levels, as well as multiply the circuit area (with a dense population, large ZD bodies will store several dozen U2 circuits).



Fig. 2. Universal PCB configurations for mounting in ZD enclosures.

Text prepared by Transfer Multisort Elektronik Sp. z o.o.

The original source of text: tme.eu



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