The 19-inch rack is the standard frame or enclosure for the installation of some electronic equipment modules. Each module has a front panel that is 19 inches wide (48.3 cm). The 19-inch dimension includes an edge, or "ear", which protrudes on each side allowing the module to be tied to a rack frame with screws. Common uses include servers, telecommunications, video broadcasting, lighting, audio, and scientific laboratory equipment.
Video 19-inch rack
Overview and history
Tools designed to be placed on the shelf are usually described as rack-mount , rack-mounted instruments , rack mounted systems, a rack mount chassis , subrack , rack mountable , or occasionally just shelf . Elevation of electronic modules is also standardized as a multiple of 1.752 inches (44.50 mm) or one shelf unit or U (less RU). Industrial standard shelf cabinet is 42U high.
The term relay rack first appeared in the phone world. In 1911, the term was also used in railway signaling. There is little evidence that these initial shelf dimensions are standardized.
The 19-inch rack format with a 1.75-inch (44.45 mm) rack unit was established as standard by AT & amp; T around 1922 to reduce the space needed for repeater and disconnection of equipment for cable tolls.
The original repeater from 1914 was installed ad-hoc on the shelf, in wooden boxes and cabinets. After serial production begins, they are built into custom-made shelves, one per repeater. But given the rapid growth of the toll network, the AT & T engineering department has systematically redesigned, resulting in a modular factory panel family that is all "designed to be mounted on vertical support spaced 19 × half inches between centers." The height of different panels will vary... but... in all cases it becomes a full multiplier of 1 3 / 4 inch ".
In 1934, it was a standard set with tapped holes for 12-24 screws with alternating distances of 1.25 inches (31.75 mm) and 0.5 inches (12.70 mm). The EIA standard was revised again in 1992 to comply with the law publicly-invited 1988 100-418, set the U standard as 15.9 mm (0.626 inches) 15.9 mm (0.626 inches) 12.7 mm (0.500 inches), making each "U" 44.50 millimeters (1,752 inch).
The 19-inch rack format remains constant while the built-in technology has changed greatly and the range of shelves applied has been greatly expanded. The standard 19-inch (482.6 mm) rack composition is widely used throughout the telecommunications, computing, audio, video, entertainment and other industries, although the 23-inch Western Electric standard, with a 1-inch (25.4 mm) center, still used in the legacy of the ILEC/CLEC facility.
The nineteen-inch rack in the form of two posts or four posts holds most of the equipment in modern data centers, ISP facilities, and professionally designed corporate server rooms. They allow for solid hardware configuration without occupying excessive floor space or needing a rack.
The nineteen-inch rack is also often used to store professional audio and video equipment, including amplifiers, effect units, interfaces, headphone amplifiers, and even small-scale audio mixers. The third common use for rack mounted equipment is industrial power, control, and hardware automation.
Typically, the installed equipment has a front panel height of 1 / 32 inch (0.03125 inches or 0.794 millimeters) less than the specified amount of Us. Thus, the 1U rackmount computer is not 1.752 inches (44.5 mm) tall but 1.721 inches (43.7 mm) high. 2U will be 3.473 inches (88.2 mm) instead of 3.504 inches (89.0 mm). This gap allows less space above and below installed equipment so that it can be released without binding adjacent equipment.
In 1965, 19-inch long-reinforced plastic reinforced rackmount cases were patented by ECS Composites and became widely used in military and commercial applications for deployment and electronic operations. The state-of-the-art rackmount case is now also built from the stamped thermo composites, carbon fiber, and Kevlar DuPont for demanding military and commercial use.
Maps 19-inch rack
Installation of equipment
Binding
Initially, the mounting holes are tapped with certain screw threads. When the rack rails are too thin to be tapped, rivnuts or other threaded inserts can be used, and when a special class of equipment to be installed is known beforehand, some holes can be removed from the mounting rails.
Threaded mounting holes on the shelf where the equipment is often converted into a problem because the threads can be damaged or the mounting screws can be broken; both problems make the mounting hole unusable. Tapping a large number of holes that may never be used is expensive; but the tapped rack is still in use, generally for rarely changed hardware. Examples include telephone exchanges, network cabling panels, broadcast studios, and some government and military applications.
The first hole shelves were replaced with permission holes (Round Hole, Round Unthreaded Holes, and Versa Rail). The holes are large enough to allow the bolts to be inserted freely without being wrapped, and bolts tied in place using the cage nuts. If any nuts are removed or bolts are broken, the nut is easily removed and replaced with a new one. Production of permission-hole racks is cheaper because hole tapping is removed and replaced with fewer and less expensive cowpeople.
The next innovation in the shelf design is a square-hole rack. Square perforated shelves allow bolt-mounting, such that rack mounted equipment only needs to be inserted and connected into a square hole hole. The installation and disposal of hardware in a square hole rack is very easy and without bolts, where equipment weight and small retention clips are all that is required to hold the equipment in place. Older equipment intended for circular racks or tapped holes can still be used, with the use of cage nuts made for square-hole racks.
Structural support
The rack-mountable equipment is traditionally installed by bolting or cutting its front panel onto the shelf. In the IT industry, it is common for network/communications equipment to have multiple mounting positions, including desk and wall mounting, so that rack-mounted equipment will often feature L-brackets that need to be screwed or bolted to the equipment before mounting on the shelf 19 inches. With the prevalence of 23-inch shelves in the Telecoms industry, the same practice is common, but with equipment that has 19-inch and 23-inch brackets that allow it to be installed on an existing shelf.
The main structural weakness of front-mounted support is the shear stress placed on the mounting rail and the front end of the apparatus. As a result, the 4-post rack becomes common, with shelves featuring a pair of banners mounted on the mirror. Because the distance between the front and rear mount posts may vary between rack and/or rack shelf vendors (some shelves may incorporate front and rear rear movable rails, for example APC SX-range racks), it is common for equipment with brackets 4-pole installation, to have adjustable rear bracket.
Servers and deep equipment parts are often installed using locked rails to the front and rear (as above, it is common for the rails to have manageable depth), allowing equipment to be supported by four posts, while also allowing it to be easily installed and removed.
Although there is no standard for the depth of the equipment, or determining the outside width and depth of the cage rack itself (incorporating structures, doors and panels containing the mounting rails), there is a tendency to 4-post shelves to be 600 mm (23.62Ã, di) or 800Ã , Mm (31.50Ã, in) wide, and for them to be 600 mm (23.62 inches), 800 mm (31.50 in) or 1,010 mm (39.76Ã, in) deep. This of course varies according to manufacturer, rack design and purpose, but through common inhibiting factors (such as elevated tile floor dimensions), this dimension has become very common. The extra width and depth allow cabling to be routed easily (also helps maintain bend radius for fiber and copper cables) and deeper equipment for use. A common feature in an IT rack is the mounting position for the "Zero-U" accessory, such as the PDU (power distribution unit) and the vertical cable manager/channel, which utilizes the space between the rear rails and the rack sides of the enclosure.
The required strength of post placement means they are always not just flat strips but are actually more folded strips that are arranged around the corner of the shelf. Posts are usually made of steel about 2 mm in thickness (official standard recommends at least 1.9 mm), or aluminum is slightly thicker.
Shelves, especially the two-post shelves, are often secured to the floor or adjacent building structures in order not to fall. This is usually required by the local building code in the seismic zone. According to Telcordia Technologies Generic Requirements, the GR-63-CORE document, during an earthquake, telecommunications equipment is subjected to movement that can damage the framework of equipment, circuit boards, and connectors. The amount of motion and voltage generated depends on the structural characteristics of the building and the framework within which the equipment is contained, and the severity of the earthquake. Seismic shelves are rated under GR-63, NEBS Requirements: Physical Protection, available, with Zone 4 representing the most demanding environments. GR-3108, General Requirements for Out-of-Network Network Equipments (OSP), determines the opening of a compatible 19-inch compatible seismic rack.
Rel (slides)
Heavy equipment or equipment normally accessed for service, attaching or removing at all four corners simultaneously will cause problems, often not directly attached to the rack but mounted through a rail (or slide). A pair of rails are mounted directly onto the rack, and the equipment then slips onto a rack along the rails, which supports it. When in place, the equipment may also be bolted to the shelf. The rails can also fully support the equipment in a position where it has slid out of the shelf; this is useful for inspection or maintenance of equipment that will then slide back onto the shelf. Some slide racks even include a tilt mechanism that allows easy access to the top or bottom of fixtures that are mounted on the shelf when fully extended from the shelf.
Slides or rails for computers and other data-processing equipment such as disk arrays or routers often need to be purchased directly from equipment manufacturers, as there is no standardization of the thickness of the equipment (measurement from the rack to equipment) or means for rail mounting.
The rail kit may include the cable management arm (or CMA), which folds the cables attached to the server and allows them to expand neatly when the server slides out, uninterruptedly.
Computer setup
Computer servers designed for rack-mounting can include a number of additional features to make the server easy to use on the shelf:
- The sliding rails can lock various extended positions to prevent equipment from moving when extended out of the rack for service.
- The server itself may lock pins on its sides that just fall into the slots on extended rail assemblies, in a similar way to a removable kitchen drawer. This allows easy installation and server deletion as there is no need for servers being held in the air while someone tightens each rail to the server side with screws.
- Some rack-mount hardware manufacturers include folding cable trays on the back of the server, so the cables are stored into neat and tidy channels when inside the rack, but can span into long lanes when pulled out of the shelf, allowing the server to continue plugged in and operating normally even when fully extended and suspended in the air in front of the shelf. This equipment simplifies maintenance, but at the cost of providing air flow restrictions.
- The rack-optimized server can duplicate indicator lights on the front and back of the rack to help identify machines that require attention, or provide a separate "identify" LED indicator on both sides of the server (which can be enabled in the software or by pressing the corresponding button ). Because some configurations allow more than fifty 1U servers on a single rack, it provides a simple method of determining which machine is having problems while on the rack.
- The handle can be provided at the rear of the server rails, to help pull or push the server without having to pull the cable.
When there are multiple computers on one rack, it is not practical for each to have a separate keyboard, mouse, and monitor. In contrast, KVM switches or LOM software are used to share a set of keyboard/video/mouse among many different computers.
Since the mounting hole setting is vertically symmetrical, it is possible to install equipment that can be mounted on the shelf in reverse. However, not all equipment is suitable for this type of installation. For example, most optical disk players will not work inversely because the mechanism of the driving force does not clutter the disc.
Shelf Type
The 19-inch server rack can vary in quality. Standard 19-inch rack cabinets typically have 42u height, 19 inch width (482.60 mm), and a depth of 36 inches (914.40 mm). The newer server rack cabinets equipped with adjustable mounting rails allow users to place rails at shorter depths if needed. There are many dedicated server racks including soundproof server racks, air-conditioned server racks, rated NEMAs, seismic ratings, open, narrow frames, and even 19 inch miniature racks for smaller applications.
Shelves that carry telecom equipment such as routers and switches often have extra width to accommodate many wires on the sides.
Four-post cabinet rack
The four-post rack allows rail installation to support front and rear equipment. These shelves may be open in construction without sides or doors, or may be enclosed by front and/or rear doors, side panels, and peaks. Most data centers use a four-post rack.
Two-post relay shelf
Two-post rack provides two vertical posts. These posts are usually heavy metering or aluminum extrusion. The top and wide legs connect the pole and allow the shelf to be securely attached to the floor and/or roof for seismic security. The equipment can be mounted close to its center of gravity (to minimize the load on its front panel), or through the front panel holes of the appliance. The name Relay Racks comes from the original two-post rack that holds telephone relays and switching equipment. The two-post rack is most commonly used for telecommunication installations.
ATA road bookcase
19 "equipment that must be frequently removed or protected from harsh treatment may be placed in an ATA approved road case.Case cases are usually made of PVC coated plywood side, united by extrusion aluminum edges, steel angles, handles and hooks usually have wheels for easy transportation Road racks have different heights based on 1U standards and different depths Unassociated cases only install 19 "mounting rails in the case. To protect the equipment from shock and vibration rack using inner and outer cases. These cases can be isolated with a thick layer of foam or can use spring loaded shock absorbers. Tourists musicians, theater productions, and sound and light companies use the road rack.
Cooling
There is no standard for airflow and cooling equipment installed on the shelf. Various airflow patterns can be found, including the front intake and rear exhaust, as well as the side intake and exhaust. Low-wattage devices may not use active cooling, but use only passive thermal radiation and convection to remove heat.
For a rack-mounted computer server, the device generally absorbs air on the front and discards on the back. This prevents circular airflow in which heat dissipation air is recirculated through adjacent devices and causes excessive heat.
Although open frame shelves are the least expensive, they also expose air-cooled equipment to dust, fibers, and other environmental contamination. A closed enclosed cabinet with a forced fan allows air filtration to protect equipment from dust.
Large server rooms will often group shelf closets together so that shelves on both sides of the hall are either front or rear facing, which simplifies cooling by supplying cold air to the front of the rack and collecting hot air from the rear of the rack. These alleys themselves can be inserted into cold air containment tunnels so that the cooling air does not move to other parts of the building where it is not needed or mixes with hot air, making it less efficient. Increased or faulty floor cooling in the server room can serve the same purpose; they allow cooling airflow to the equipment through the space below the floor to the bottom of the closed shelf closet.
The difficulty with a forced air-conditioning fan on the shelf equipment is that fans can fail due to age or dust. The fans themselves can be difficult to replace. In the case of network equipment, it may be necessary to unplug 50 or more cables from the device, disconnect the device from the rack, and then unload the chassis of the device to replace the fan.
However, some rack equipment has been designed to facilitate fan replacement, using a fast-changing fan tray that can be accessed without removing cables or devices from the rack, and in some cases without shutting down the device so that the operation is not interrupted during replacement.
Specifications
The formal standard for 19-inch (482.6 mm) rack is available from the following:
- Electronic Industry Alliance EIA-310-D, Cabinets, Racks, Panels, and Related Equipment, dated September 1992. (Latest Standard Now REV E 1996)
- requirements of the CEA-310-E Consumer Electronics Association for Cabinets, Panels, Racks and Subracks., dated December 14, 2005
- International Electrotechnical Commission - Some documents are available in both French and English versions.
- IEC 60297 Mechanical structure for electronic equipment - Dimensions of mechanical structure of series 482.6 mm (19 in)
- IEC 60297-1 Replaced by IEC 60297-3-100
- IEC 60297-2 Replaced by IEC 60297-3-100
- IEC 60297-3-100 Sections 3-100: Front panel basic dimensions, subracks, chassis, shelves, and cabinets
- IEC 60297-3-101 Section 3-101: Subracks and associated plug-in units
- IEC 60297-3-102 Section 3-102: Injector/extractor handle
- IEC 60297-3-103 Section 3-103: Pin of alignment and alignment
- IEC 60297-3-104 Section 3-104: Interface dimensions that depend on connectors of subracks and plug-in units
- IEC 60297-3-105 Section 3-105: Dimensions and design aspects for chassis 1U
- IEC 60297-4 Replaced by IEC 60297-3-102
- IEC 60297-5 Some documents, -100, 101, 102,... 107, replaced by IEC 60297-3-101
- IEC 60297 Mechanical structure for electronic equipment - Dimensions of mechanical structure of series 482.6 mm (19 in)
- Deutsches Institut fÃÆ'¼r Normung DIN 41494 - Many documents are in German but some documents are available in English.
- DIN 41494 Practice equipment for electronic equipment; the mechanical structure of the 482.6 mm (19 inch) series
- DIN 41494-7 Dimensional cabinets and rack suites .
- DIN 41494-8 Components on the front panel; installation conditions, dimensions
- DIN IEC 60297-3-100 (see above in IEC section)
- DIN 41494 Practice equipment for electronic equipment; the mechanical structure of the 482.6 mm (19 inch) series
The rack mounting equipment consists of two parallel metal strips (also referred to as "pole" or "stand panel") that stand vertically. The posts each have a width of 0.625 inches (15.88 mm), and are separated by a 17.75 inch (450.85 mm) slit, giving an overall 19 inch (482.60 mm) total rack width. The post has a hole in it periodically, with both posts matched, so each hole is part of the horizontal pair with a center-to-center spacing of 18,312 inches (465.12 mm).
The holes in the post are arranged vertically in repeating the set of three, with center-to-center separation of 0.5 inches (12.70 mm), 0.625 inches (15.88 mm), 0.625 inches (15.88 mm). The hole pattern repeats every 1.75 inches (44.45 mm).
Stacked holes can be tapped (typically 10-32 UNF threads, or more rarely, 6mm metrics) or have square holes for the cage nuts.
Shelf Unit (U)
Shelves are divided into areas, height 44.50 millimeters (1.752 inches), where there are three complete pit pairs in a vertical symmetrical pattern, centered holes 6.35 millimeters (0.25 inches), 22.25 millimeters (0.88 inches) ), and 38.15 millimeters (1.50 inches) from the top or bottom of the area. Such areas are commonly known as U , for units , or, in German, HE , for HÃÆ'¶heneinheit , and the height inside the shelf is measured by this unit. Rack-mountable equipment is usually designed to occupy multiple integer numbers of U. For example, an oscilloscope may be 4U high, and rack-mountable computers are mostly between 1U and 4U high. The blade server cover may require 10U.
Sometimes, one can see a fractional U device like a 1.5U server, but this is less common.
The rack height may vary from a few inches, as in a broadcast console, to a rack mounted on the floor whose interior is 45 racks (200.2 cm or 78.82 inches) high, with 42U being a common configuration. Many wall-mounted industrial fixtures have 19-inch rack rails to support the installation of equipment.
Related standards
11-foot frame
Frames for holding rotary-call telephone equipment are generally 11 feet tall (3.51 m). A series of studies led to the adoption of a 7 foot (2.1 m) tall frame, with a modular width in 1 foot 1 inch (0.33 m) multiples - most often 2 feet 2 inches (0.66 m) wide.
ETSI Shelf
The ETSI rack is defined by the European Telecommunications Standards Institute (ETS 300 119). The right rim of the right rail rail to the left of the left rail mount is 535 millimeters (21.1 inches). Because 535 mm is very close to 21 inches, this shelf is sometimes called a 21 inch rack. The gap between the poles is 500 millimeters (19.69 inches). Because the 19-inch equipment has a maximum width of 17 1 / 4 inch (438.15 mm), they can easily mounted on the ETSI rack using ETSI bracket or adapter plate.
In contrast to the "19-inch world", ETSI also defines the shelf enclosure size: four permitted widths are 150, 300, 600, 900 millimeters (5.9, 11.8, 23.6, 35.4 inches). ) and two allowable depths are 300 and 600 millimeters (12 and 24 inches). The distance of the hole is 25 millimeters (0.98 inches).
23 inch rack
A 23-inch rack (580 mm) is used for home phones (mainly), computers, audio, and other equipment though less common than 19-inch racks. The size shows the width of the faceplate for installed equipment. The shelf unit is a measure of vertical distance and is common to both 19 and 23 inch racks.
The hole spacing is at center 1 inch (25 mm) (Western Electric standard), or equal to 19 inch rack (480 mm) (0.625 in 15.9 mm).
Open Shelf
Open Rack is an installation system designed by the Facebook Open Compute Project that has the same outer dimensions as a typical 19-inch rack (eg 600 mm width), but supports a wider 547 millimeter (21.5 inch) equipment module.
Gallery
19 inch rack image
See also
- Data center
- Horizontal pitch
- Shelf units
- Transit case, for rack case
References
External links
- Media related to 19 "-Ray on Wikimedia Commons
Source of the article : Wikipedia
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