Racks, racks, are metal enclosures into which subracks, plug-in assemblies, chassis and enclosures for system components, peripherals, storagedevices, servers, single- board computers, transmitters, power supplies, fans, powerdistribution units and other components can be installed. The rack forms a self-contained, fully wired system. It saves space, supplies power and cooling to the plug-in modules, and provides slide-in options for retrofits.
Racks, which have become established in almost all areas of technology, have a standardized rack width of 19", which corresponds to 482.6 mm. This width corresponds to the front width of the subracks. They have a horizontal hole grid for the attachment of guide rails into which the subracks, the plug-in units with the printed circuit boards can be pushed and fixed. This hole pattern is subdivided into vertical height units(HE) and horizontal pitch units( HP).
The racks have a fixed reference height based on the height unit (HE), which is referred to as a unit (U) in English. A height unit is 1.75" or 44.45 mm. Most rack modules have height units of 1U, 2U, 3U or 4U. There is also the pitch unit ( TE), Horizontal Pitch(HP), which is equal to 1.5" or 5.08 mm. It is used for the perforated rails in which the rack modules are screwed. The rack depth depends on the depth of the slide-in components and the space required for air circulation, and the rack height depends on the number and size of the slide-in components.
The slide-in boards have standardized formats, with the euroboard and double euroboard formats being the most common. The height of the slide-in units is specified in height units (U-system). The plug-in connections for the slide-in boards are located on the backplane. Racks come in all imaginable colors, sizes and shapes; only the size is specified by Electronics Industry Association( EIA) in the EIA-310 standard. Internationally, this standard of the International Electrotechnical Commission( IEC) is known as IEC 60297 and in Germany as DIN 41494.
Racks can be open on two or four sides, they can be used for representative purposes or they can meet certain safety requirements.
Important aspects in the selection of racks are heat loss, possible interference radiation that can affect the function of the components, room temperature, cooling, power supply and cable routing, and not to be neglected are the aspects of safety.