Thevenin generator - For a given load, it is possible to consider the power supply as a voltage generator, referred to as a Thevenin generator, made up of a perfect voltage Uo generator, in series with an internal impedance Zs - n Uo is the voltage measured across the load terminals, given that the load is to be disconnected (load terminals forming an open circuit), n Zs is the equivalent impedance as seen from the load terminals (again considered an open circuit), obtained by short-circuiting the upstream voltage generator(s).
Backup time - Time during which the UPS can supply the rated load with nominal-quality power while the mains are down. This time depends on the battery and the efficiency of the UPS. Typical backup ranges from five minutes to several hours.
Intermittent Test - A test during which a battery is subjected to alternate periods of discharge and rest according to a specified discharge regime.
Specific Energy - The ratio of the energy output of a cell or battery to its weight (Wh/kg). This term is used interchangeably with gravimetric energy density.
Constant Current Discharge - A battery discharge regime whereby the current drawn during the discharge remains constant.
Charger - Device associated with the rectifier and used to supply the battery with the electrical power (DC current) required to recharge and/or float charge the battery, thus ensuring the rated backup time.
COS phi - A measure of the phase shift between the current wave and the voltage wave observed at the terminals of a load supplied with AC power at a given frequency.
