uninterruptible power system


Also found in: Acronyms.

uninterruptible power system

[¦ən¦in·tə′rəp·tə·bəl ′pau̇·ər ‚sis·təm]
(electricity)
A system that provides protection against primary alternating-current power failure and variations in power-line frequency and voltage. Abbreviated UPS.

Uninterruptible power system

A system that provides protection against commercial power failure and variations in voltage and frequency. Uninterruptible power systems (UPS) have a wide variety of applications where unpredictable changes in commercial power will adversely affect equipment. This equipment may include computer installations, telephone exchanges, communications networks, motor and sequencing controls, electronic cash registers, hospital intensive care units, and a host of others. The uninterruptible power system may be used on-line between the commercial power and the sensitive load to provide transient free well-regulated power, or off-line and switched in only when commercial power fails.

There are three basic types of uninterruptible power system. These are, in order of complexity, the rotary power source, the standby power source, and the solid-state uninterruptible power system.

The rotary power source consists of a battery-driven dc motor that is mechanically connected to an ac generator. The battery is kept in a charged state by a battery charger that is connected to the commercial power line. In the event of a commercial power failure, the battery powers the dc motor which mechanically drives the ac generator. The sensitive load draws its power from the ac generator and operates through the outage.

The standby power source consists of a battery connected to a dc-to-ac static inverter. The inverter provides ac power for the sensitive load through a switch. A battery charger, once again, keeps the battery on full charge. Normally, the load operates directly from the commercial power line. In the event of commercial power failure, the switch transfers the sensitive load to the output of the inverter.

The solid-state uninterruptible power system has a general configuration much like that of the standby power system with one important exception. The sensitive load operates continually from the output of the static inverter. This means that all variations on the commercial power lines are cleaned and regulated through the output of the uninterruptible power system. A commercial power line, known as a bypass, is provided around the uninterruptible power system through a switch. Should the uninterruptible power system fail at some point, the commercial power is automatically transferred to the sensitive load through the switch. This scheme is known as an on-line automatic reverse-transfer uninterruptible power system.

An uninterruptible power system consists of four major subsystems: a method to put energy into a storage system, a battery charger; an energy storage system, the battery; a system to convert the stored energy into a usable form, the static inverter; and a circuit that electrically connects the sensitive load to either the output of the uninterruptible power system or to the commercial power line, the transfer switch. The position of the transfer switch is controlled by a monitor circuit. Generally the switch in an uninterruptible power system is a high-speed solid-state device that can transfer the load from one ac source to another with little or no break in power. See Electric power systems, Electric switch

uninterruptible power system

An electric power system which provides continuity of power, to the apparatus or appliances being served, without discernible interruption upon failure of the normal power supply.
References in periodicals archive ?
Major Points from Table of Contents for China Uninterruptible Power System (UPS) Industry Report, 2014-2017
Uninterruptible power systems protect computers and data from costly damage that can occur as the result of commonly experienced power-quality problems such as brownouts, surges and spikes.
8 /PRNewswire/ -- Powerware Corporation announced today an innovative new addition to its line of uninterruptible power systems (UPSs) - the Powerware 9125.
April 14 /PRNewswire/ -- Powerware(R) Corporation unveiled today the latest addition to its line of Powerware uninterruptible power systems (UPSs) -- the Powerware 3115.
He begins with the basics of AC power systems, including their elements and architecture, moving to power generation systems, the power factor, including correction techniques, power transformers, capacitors, semiconductors, rectifier and filter circuits, power electronics, origins of AC line disturbances, power disturbance characterization, protection methods, the motor-generator set, uninterruptible power systems, power conditioning devices, transient suppression (including at the circuit level and in facility wiring), grounding (practices, tower elements and system design in the facility), standby power systems, designing for tolerance of faults, energy efficiency, safety and protection systems.
Officials, however, point out that improved lithium-ion batteries have application in cell phone towers, autos, emergency equipment and uninterruptible power systems.
FORTY-FIVE jobs are being created following the acquisition of part of an established company specialising in uninterruptible power systems.
Invensys Powerware has announced the availability of the Powerware 9320, the latest in its line of industry-leading uninterruptible power systems (UPSs).
an award-winning manufacturer of on-line uninterruptible power systems (UPS), ac line regulators and voltage and frequency converters for mission-critical applications, moved into a new facility in Irwindale, California.
The ePDUs provide advanced metering, monitoring and management capabilities and complement uninterruptible power systems, distributing power to up to 45 receptacles per ePDU.
Invensys Powerware has introduced the Powerware 9350 family of high- end uninterruptible power systems (UPS), designed to provide continuous clean power for financial, medical, data center and networking, communications, and technology-based manufacturing applications.