UL 1778 Uninterruptible Power Systems

standard by Underwriters Laboratories, 03/14/2003

Full Description

These requirements cover uninterruptible power supplies (UPS) rated 600 volts or less ac or dc that are intended for installation in accordance with the National Electrical Code, NFPA 70. During normal operation, the UPS allows the primary or normal power source to deliver ac power to the protected load through either the power conversion portion of the UPS or a bypass source. The power conversion portion of the UPS consists of a rectifier, an inverter, or both. During periods of power fluctuations, or power outages, or both, the connected load receives ac power from the battery supply and power conversion portion of the UPS.

Products that are used with UPS and that are covered by this standard include:Remote battery supply cabinets with or without batteriesRemote status panelsBypass switchesMaintenance bypass switchesRectifier, power conversion units, or bothPower distribution panelsA battery supply (see ) used with a UPS covered by this standard may consist of any of the following described in (a) - (c):

1.A battery supply that is integral with the UPS. The batteries may or may not be furnished with the UPS. 2.A battery supply that is contained in a remote cabinet. For a cord-and-plug-connected UPS having an ac input rating of 20 amperes or less and 125 volts ac maximum, the battery supply is furnished with the UPS. For all other UPS intended for use with a remote battery and cabinet assembly, the battery supply may or may not be furnished with the UPS. 3.A battery supply that is contained in a separate battery room. This type of battery supply may or may not be furnished with the UPS.

These requirements cover static type UPS - not rotary type UPS.

Uninterruptible power supplies for use in health care facilities are covered by these requirements in addition to the applicable requirements in the Standard for Electric Medical and Dental Equipment, UL 544.