Inverter (off-line or stand-by) - UPS configuration in which the inverter is parallel-mounted to the load supply line and backs up the mains. This configuration offers a substantial cost reduction but is applicable only to low outputs, under 3 kVA, because it results in an interruption lasting up to 10 ms during transfer and does not filter inrush currents.
Protection index (IP) - Index indicating the capacity of an electrical device to resist environment conditions. It is made up of three digits (e.g. IP 205), each corresponding to a type of environmental risk. The higher the number, the greater the capacity to resist. First digit (0 to 6) - capacity to resist penetration by solid objects. Second digit (0 to 7) - capacity to resist penetration by liquids. Third digit (0, 1, 2, 3, 5, 7, 9) - mechanical strength.
Coulomb - The amount of electricity transported by a current of one ampere flowing for one second.
Tolerance in % - Limit for allowable variations for a given quantity, expressed as a percent of the rated value.
Gassing - The evolution of gas from one or more of the electrodes in a cell. Gassing commonly results from local action (self-discharge) or from the electrolysis of water in the electrolyte during charging.
Bobbin - A cylindrical cell design utilizing an internal cylindrical electrode, and an external electrode arranged as a sleeve inside the cell container.
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).