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LAN and distribution cabinets are used in networks to accept the structured cabling and various network components such as patch panels, switches and routers. In order that the often large numbers of copper and fibre-optic cables can be received, the cabinets must on the one hand be able to withstand high stresses while on the other hand must offer installation possibilities for ordered cable routing and fixing.
The diversity of requirements in network cabinets
The primary requirements in cabinets used in networking are ease and low cost of assembly, a high load-bearing capacity, logical assembly and unrestricted cable ducting. Versatility is called for, but with a minimum of components. Here cable management has a key function; it is necessary to make available all options for cable routing and fixing, for both assembly and accessory components.Depending on their location and application, the cabinets are fitted with or without doors and side panels.Where front and rear doors are required, these are mounted on hinges giving full 180° opening to allow better accessibility. The front door is normally made from safety glass, with or without frame. Side panels and doors can be supplied with safety locks to prevent unauthorised access. An ideal configuration is the integration of two 19" sections (front and rear) in which to fit the passive components. The 19" panel/slide mounts are normally recessed, allowing sufficient space for the bending radii of the patch cables. Non-19" components are placed on fixed or removable lower shelves. Such requirements are fulfilled by most of the cabinet types on the market. Yet in precisely the area of cable management, cable routing and fixing there are often vague design concepts that hinder a cabling arrangement that is simple, ordered and easy to subsequently modify. Nor are all cabinets equally well built to withstand the high stresses caused by large numbers of cables. To this end Schroff has developed its Varistar cabinet platform (Fig.1), which comprises a welded frame that may be covered in a variety of finishes and be fitted with the optimal set of components and accessories for a LAN or distribution cabinet.
The diversity of requirements in network cabinets
The primary requirements in cabinets used in networking are ease and low cost of assembly, a high load-bearing capacity, logical assembly and unrestricted cable ducting. Versatility is called for, but with a minimum of components. Here cable management has a key function; it is necessary to make available all options for cable routing and fixing, for both assembly and accessory components.Depending on their location and application, the cabinets are fitted with or without doors and side panels.Where front and rear doors are required, these are mounted on hinges giving full 180° opening to allow better accessibility. The front door is normally made from safety glass, with or without frame. Side panels and doors can be supplied with safety locks to prevent unauthorised access. An ideal configuration is the integration of two 19" sections (front and rear) in which to fit the passive components. The 19" panel/slide mounts are normally recessed, allowing sufficient space for the bending radii of the patch cables. Non-19" components are placed on fixed or removable lower shelves. Such requirements are fulfilled by most of the cabinet types on the market. Yet in precisely the area of cable management, cable routing and fixing there are often vague design concepts that hinder a cabling arrangement that is simple, ordered and easy to subsequently modify. Nor are all cabinets equally well built to withstand the high stresses caused by large numbers of cables. To this end Schroff has developed its Varistar cabinet platform (Fig.1), which comprises a welded frame that may be covered in a variety of finishes and be fitted with the optimal set of components and accessories for a LAN or distribution cabinet.
Fig.1. The Varistar electronics cabinets platform for networking technology
High load-bearing capacities
Since the demands made on these cabinets can vary widely in some respects, the cabinet frame is available in two versions. The 'Slimline' version guarantees a maximum load-bearing capacity of up to 400 kg. The specially-developed hollow-chamber profile used here fulfils the requirements of classes DL5 and DL6 of IEC 61 587-1 for static and dynamic loading with the minimum of material. For applications requiring higher static load-bearing capacities or indeed earthquake proofing a second frame type is available. The 'Heavy Duty' version uses the same hollow-chamber profile, but which here is lengthened in the main loading direction and thus even more stable. This version guarantees a maximum static load-bearing capacity of up to 800kg. Seismic tests conducted to IEC 61 587-2 certify the earthquake proofing of the platform to Bellcore Zone 3, and when reinforced in the corners with additional angle sections, up to Bellcore Zone 4.
Consistent cable routing
In precisely the area of cable management, cable routing and fixing there are often differing design concepts for a simple, ordered cabling arrangement that can also be easily modified or expanded while in service. There are three basic types of cable found in a TK cabinet: copper and fibre-optic data cables and power cables. These produce differing levels of mechanical loading and must be fitted into the cabinet without imposing bending, tension, pressure or torsional forces. Improper handling and fitting affects the respectively electrical or optical characteristics of the cables, so reducing their transmission bandwidths and range.
The cable routing in Varistar makes a consistent distinction between the various areas. The ordered routing and fixing of all cable types is assured through four defined zones (Fig.2). Zone 1 is situated in front of the built-in components in the 19" plane. Here, patch cables are run horizontally between the distribution panels (Fig.3). Zone 2 is located to left and right of the 19" plane; here the patch cables are run vertically between the individual components in a type of vertical duct. In Zone 3, which extends laterally through the cabinet depth behind the 19" plane, data cables are run from the cable entry in the top or base plate to the rear of the distribution panel. Zone 4, on the rear of the cabinet, forms an alternative to zone 3 for 600mm-width cabinets or in situations where, owing to its location, a cabinet is not accessible from the rear. As a rule, the zone 4 openings in the top cover are used for active heat dissipation via internal fans. This is necessary where active components are fitted in the cabinet as well as passive components.
Since the demands made on these cabinets can vary widely in some respects, the cabinet frame is available in two versions. The 'Slimline' version guarantees a maximum load-bearing capacity of up to 400 kg. The specially-developed hollow-chamber profile used here fulfils the requirements of classes DL5 and DL6 of IEC 61 587-1 for static and dynamic loading with the minimum of material. For applications requiring higher static load-bearing capacities or indeed earthquake proofing a second frame type is available. The 'Heavy Duty' version uses the same hollow-chamber profile, but which here is lengthened in the main loading direction and thus even more stable. This version guarantees a maximum static load-bearing capacity of up to 800kg. Seismic tests conducted to IEC 61 587-2 certify the earthquake proofing of the platform to Bellcore Zone 3, and when reinforced in the corners with additional angle sections, up to Bellcore Zone 4.
Consistent cable routing
In precisely the area of cable management, cable routing and fixing there are often differing design concepts for a simple, ordered cabling arrangement that can also be easily modified or expanded while in service. There are three basic types of cable found in a TK cabinet: copper and fibre-optic data cables and power cables. These produce differing levels of mechanical loading and must be fitted into the cabinet without imposing bending, tension, pressure or torsional forces. Improper handling and fitting affects the respectively electrical or optical characteristics of the cables, so reducing their transmission bandwidths and range.
The cable routing in Varistar makes a consistent distinction between the various areas. The ordered routing and fixing of all cable types is assured through four defined zones (Fig.2). Zone 1 is situated in front of the built-in components in the 19" plane. Here, patch cables are run horizontally between the distribution panels (Fig.3). Zone 2 is located to left and right of the 19" plane; here the patch cables are run vertically between the individual components in a type of vertical duct. In Zone 3, which extends laterally through the cabinet depth behind the 19" plane, data cables are run from the cable entry in the top or base plate to the rear of the distribution panel. Zone 4, on the rear of the cabinet, forms an alternative to zone 3 for 600mm-width cabinets or in situations where, owing to its location, a cabinet is not accessible from the rear. As a rule, the zone 4 openings in the top cover are used for active heat dissipation via internal fans. This is necessary where active components are fitted in the cabinet as well as passive components.
Fig.2. Four defined zones allow organisation
Fig.3. Zone 1 contains only patch cables
Cable fixing and routing
Cabling in zones 1 and 2 is almost always without fixing, since this cabling is more frequently modified by patch work. A strain relief is provided particularly in zones 3 and 4. This ensures that the cable's own weight does not give rise to any tension forces. In 90% of cases strain relief in zone 3 is provided by C-rails, to which the cable bundles are fixed with suitable clips (Fig.4).
Cabling in zones 1 and 2 is almost always without fixing, since this cabling is more frequently modified by patch work. A strain relief is provided particularly in zones 3 and 4. This ensures that the cable's own weight does not give rise to any tension forces. In 90% of cases strain relief in zone 3 is provided by C-rails, to which the cable bundles are fixed with suitable clips (Fig.4).
Fig.4. Strain relief in zone 3
Schroff has also developed other simple but effective solutions for the individual zones in Varistar. The patch cables in zone 1 are passed horizontally via cable management brackets in round steel or plastic to zone 2. These brackets are attached to a 19" patch panel 1U in height via a type of square bayonet lock (engages with a quarter turn). Semicircular and quarter-circular elements are also provided here that are specifically designed to accommodate fibre-optic patch cables.
In zone 2 cable eyes of three different sizes are used, according to the dimensions of the cabinet. In the classic 800mm-wide x 800mm deep networking cabinet an area of 100mm (w) x 150mm (d) can be completely used in zone 2. These eyes may be mounted directly in the 25mm grid of the frame or laterally on the 19" plane. For very large numbers of cables a bracket is available whose dimensions of 100mm (w) x 300mm (d) extend far into zone 3.
In zone 2 cable eyes of three different sizes are used, according to the dimensions of the cabinet. In the classic 800mm-wide x 800mm deep networking cabinet an area of 100mm (w) x 150mm (d) can be completely used in zone 2. These eyes may be mounted directly in the 25mm grid of the frame or laterally on the 19" plane. For very large numbers of cables a bracket is available whose dimensions of 100mm (w) x 300mm (d) extend far into zone 3.
