FAQs - Rackmount UPS

Information on rackmount UPS systems including U height and depth sizes, battery trays, slides and accessories used in server rack installations.

When you select a rackmounted UPS it is important to ensure that the depth of the uninterruptible power supply is smaller than the internal depth of the rack and that there is at least 100-200mm for cable bend radius and access to the UPS outlet sockets or hardwired terminals.

A server rack UPS system is an uninterruptible power supply designed to be installed within a 19inch server rack or cabinet. The rack UPS will typically attach to slide out rails or may be placed onto a suitable supporting shelf within the serve rack. A UPS may be classed as a rack mount UPS or a dual system. A dual server rack UPS can be installed as a rack mount UPS or turned 90degrees to stand as a tower UPS. In the tower format, stabilising feet are normally attached. Care should be take when selecting a server rack UPS to make sure that its depth is less than the depth of the server rack into which it is to be placed. A 500mm deep rack mount UPS will require an 800mm deep server rack or cabinet.

There are weight and heat output issues to consider when rack mounting a UPS system and the best position is in the base or lower middle section of the server rack. At height in an otherwise empty server rack there is an issue of the rack becoming top-heavy. Heat also rises and the UPS system will output some heat internal to the server rack. It is also important to ensure the batteries are within a 20-25˚C ambient to prevent them being damaged by excessive heat; this will degrade their working life.

A rackmount UPS may include a built-in battery or require an external battery pack which can be housed in a rack mountable tray or a metal cabinet. If there is space within the server rack then it can make sense to install the battery tray internally underneath the UPS system. If there is little or no internal space then the battery pack will need to be placed external to the server rack and supplied as a floor standing battery cabinet. This applies to small power ratings and short duration runtimes.

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