Many rack-mounted power programs are specified as being 1U, 2U, 3U, and many others. What does this imply? For digital tools racks (e.g., 19 or 23 inches extensive), the time period 1U is used to outline one rack unit of height.
1U equals 1.75-inches (44.45mm) of rack height. Subsequently, a 2U rack mount height could be 2 x 1.75", which equals 3.5-inches high. A 3U height could be 3 x 1.75" = 5.25-inches.
It needs to be famous that the 1U, 2U, 3U, and many others., heights are most dimensions. With a view to enable for mechanical tolerances and to supply some house between panels, usually, for every 1U of height producers might deduct about 0.03" (see Picture #1). For instance, a 2U panel, which has a nominal height of 3.50" could also be solely 3.44" high [3.50" – (2 x 0.03") = 3.44"].
Particular person power provides are typically mounted inside rack-mounted enclosures that require integral power. In these instances, the power provide must be a bit shorter than the tools’s general height to permit for the highest and backside covers. So a 1U high enclosure-mountable power provide must be shorter than 1.75-inches; a 2U enclosure-mountable provide must be shorter than 3.5-inches, and so forth (see Picture #2).
Since we nonetheless stay in an English and Metric measurement world, listed here are a few useful conversion elements: 1 inch = 25.4 millimeters (mm), 1 mm = 0.03937 inch
As a facet note, Lambda ran a intelligent advert marketing campaign that those that perceive what “1U” or “2U” actually means would recognize. Here's a copy of that advert, which hopefully you'll discover humorous.