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).
Switching Transients - Rapid voltage peak up to 20,000 volts with a duration of 10mS to 100mS.
Load (linear) - Load for which voltage form and current form are similar. Voltage and current are related by Ohm's law U(t) = Z x I(t).
Distortion (individual) - Ratio between the rms value of an nth order harmonic and the rms value of the fundamental.
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 Resistance Discharge - A battery discharge regime whereby the resistance of the equipment load remains constant throughout discharge.
Output (rated) - Apparent power Pn that the UPS can deliver under given load conditions (power factor = 0.8).