Power factor (l) - Ratio between the active power P supplied to a load and the apparent power S supplied to said load by an AC power supply.
Fuse - Device used for cutting off an electrical current in the event of an abusive condition.
Charge - The conversion of electrical energy, provided in the form of electrical current from an external source, to restore the chemical energy in a cell or battery.
Midpoint Voltage - The voltage of a battery midway in the discharge between the start of the discharge and the end voltage.
Voltage Delay - Time delay for a battery to deliver the required operating voltage after it is placed under load.
Filter (phase-shift) - Filter used to reduce, if necessary, the overall distortion due to the current harmonics injected into the mains upstream of a UPS by its rectifier-charger. Filtering is superior to that of a traditional filter of the L or C type.
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).