10.4.An electrical device providing an interface between the mains power supply and sensitive loads (computer systems, instrumentation, etc). The UPS supplies sinusoidal a.c. power free of disturbances and within strict amplitude and frequency tolerances. It is generally made up of a rectifier/charger and an inverter together with a battery for backup power in the event of a mains failure with virtually no time lag.

In general UPS system shall be provided for sensitive electronic equipments like computers, printers, fire alarm panel, public address system equipment, access control panel, EPABX, etc with the following provisions:

1. a) Provisions of isolation transformers shall be provided where the capacity exceeds 5 kVA.
2. b) UPS shall have dedicated neutral earthing system.
3. c) Adequate rating of protective devices such as MCB, MCCB, fuses, ELCB, etc, shall be provided at both incoming and outgoing sides.
4. d) UPS room shall be provided with adequate ventilation and/or air conditioning as per requirement.