Alternating Current - An electrical current that reverses direction    continually  – in the UK it is 50cycles a second

The temperature of the environment around a UPS power supply

Unit of measurement of electrical current

The length of time a UPS can provide AC power to a load, when normal AC mains is disconnected. Sometimes known as the ‘Run Time’

Automatic Voltage Regulation - an electronic stabiliser that ensures that the output voltage does not vary more than 10% in the case of 20% variations

Total loss of electrical power

A reduction of AC mains voltage, usually happens when demand exceeds capacity

Electricity expressed in amperes (amps), known as an intensity of electricity

An electrical current that flows on one direction (positive to negative)

A short duration in voltage decrease

The process of converting incoming AC power to DC, for conditioning and battery charging, then re-converting it into clean AC to supply the critical load. This process completely recreates the power flowing through an on-line UPS to remove all irregularities and provide pure, frequency-regulated sine wave output at all times

Ratio of total output power to input power is expressed as a percentage, usually specified at full load and nominal voltage input

Electronic circuit that only allows certain frequencies to pass

A device that produces an AC output from a DC input

Supplies load with a true sine wave. More cleaner than AC mains sine wave

Current that can flow between the live AC wire and Earth (ground)

Corrects power inequalities within a suppression range as well as providing temporary battery back-up if the power fails

The equipment or device(s) connected to the output of the UPS

Monitors the power supply and provides temporary battery power if the quality of the supply moves outside an acceptable level, or if there is a power cut

Uses double conversion technology to condition and regenerate the power supply at all times, correcting all irregularities to provide perfect sine wave AC power to the load. Online UPS systems are amongst the most advanced available and in the event of mains overvoltage or failure the UPS continues to supply the load from its battery with no transfer delay. Provided the mains power disturbance duration is less than the battery autonomy, the event remains invisible to the load

Ratio of true power versus apparent power

The length of time a UPS can provide AC Power to a load, when normal AC mains is disconnected, Sometimes known as the ‘Autonomy’

A short drop in voltage. When this occurs the load is supplied with a clean and stable sine wave from the UPS rectifier that converts AC into DC in order to charge the batteries and to supply the inverter, so that there is no disruption to the load

An ideal waveform with a smooth arcing alternating waveform, all products using AC power are designed for use with sine wave output

An abnormally high voltage that occurs briefly, usually after AC mains fails and then comes back on suddenly

The amount of time it takes for a Line Interactive UPS to sense AC mains power failure and to switch to battery power and inverter. This is measured in milliseconds.

If present on the AC mains, the UPS filters these out with a clean and stable sine wave before reaching the load

An electronic power supply that provides AC power to equipment when normal AC mains power fails

A measure of energy carried by the charge, voltage is sometimes described as the push or force of the electricity. In the UK, the AC mains voltage is 240Volts

The initial time it takes for the inverters on on-line high tier UPS’s to stabilise and to achieve optimum performance of specifications and before switching on heavy loads. Recommended for UPS’s 2kVA and above.  Warm-up time usually is about 20 seconds