Pulse Current - A periodic current drain of higher than normal drain rates.
Output (rated) - Apparent power Pn that the UPS can deliver under given load conditions (power factor = 0.8).
Nominal Voltage - The characteristic operating voltage or rated voltage of a battery.
Internal Resistance (IR) - The opposition exhibited by a circuit element to the flow of direct current (d.c.). In a cell, the internal resistance is the sum of the ionic and electronic resistances of the cell components.
Hertz - The standard unit of frequency. A frequency of one complete cycle per second is a frequency of one hertz.
Constant Power Discharge - A battery discharge regime whereby the current during the discharge increases as the battery voltage decreases.
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).