Info!! What Does 1U, 2U Or 3U Mean?

Many rack-mounted ability systems are specified every bit existence 1U, 2U, 3U, etc. What does this mean? For electronic equipment racks (e.g., xix or 23 inches wide), the term 1U is used to define 1 rack unit of measurement of height.

1U equals 1.75-inches (44.45mm) of rack height. Therefore, a 2U rack mountain tiptop would endure ii x 1.75", which equals 3.5-inches high. Influenza A virus subtype H5N1 3U tiptop would endure three x 1.75" = 5.25-inches.

It should endure noted that the 1U, 2U, 3U, etc., heights are maximum dimensions. In social club to permit for mechanical tolerances too to provide but about infinite betwixt panels, typically, for each 1U of tiptop manufacturers may deduct nearly 0.03" (see Photo #1). For example, a 2U panel, which has a nominal tiptop of 3.50" may endure solely 3.44" high [3.50" – (2 x 0.03") = 3.44"].

Individual ability supplies are sometimes mounted inside rack-mounted enclosures that require integral power. In these cases, the ability provide needs to endure a fleck shorter than the equipment’s overall tiptop to permit for the overstep too bottom covers. So a 1U high enclosure-mountable ability provide needs to endure shorter than 1.75-inches; a 2U enclosure-mountable provide needs to endure shorter than 3.5-inches, too then forth (see Photo #2).

Examples

Photo #1: This 19" rack-mountable ability organisation tin concord upwards to three plug-in, hot-swap too redundant ability supplies. The enclosure amongst mounting ears is 1.72" high (= 1.75" minus 0.03") too is thus considered 1U high.

Photo #2: This 1000-watt switch-mode ability provide is 3.25” high and, therefore, tin endure mounted inward a 2U rack-mountable enclosure, which tin vary betwixt 3.44" to 3.50" high.

Since nosotros nevertheless alive inward an English linguistic communication too Metric criterion world, hither are a twain of handy conversion factors: 1 inch = 25.4 millimeters (mm), 1 mm = 0.03937 inch

As a side note, Lambda ran a clever advertizing drive that those who sympathise what “1U” or “2U” actually way would appreciate. Here is a re-create of that ad, which hopefully yous volition uncovering humorous.