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.
UPS (parallel without redundancy) - A UPS made up of several (n) parallel-connected UPS units with equal output ratings (P) and each equipped with its battery, for large loads. The total output is equal to the number of units multiplied by their individual output (n x P). In this configuration, no UPS unit is redundant.
Battery or Pack - Two or more electrochemical cells electrically interconnected in an appropriate series/parallel arrangement to provide the required operating voltage and current levels. Under common usage, the term "battery" is often also applied to a single cell.
Micro-outage (or micro-interruption) - Total loss in the supply of power for 10 ms.
Electrolyte - The medium which provides the ion transport mechanism between the positive and negative electrodes of a cell.
Earthing system TN - Earthing system in which the exposed conductive parts are interconnected and connected to the neutral. The neutral is connected to the earth. The installation must be de-energized immediately in the event of an insulation fault.
Safety installation - Installation supplying electrical equipment which may have a direct effect on the safety of users and must therefore remain energized even in the event of a mains failure. In general, characteristics concerning the power supply and conditions for transfer to the safety source for such electrical equipment are covered by applicable regulations.
