Bypass (manual) - Manually-operated switch used to supply the load via direct connection to utility power during servicing of the UPS system.
Polarity - In electricity, the condition of being positive or negative.
Depth of Discharge - The ratio of the quantity of electricity (usually in ampere-hours) removed from a battery to its rated capacity.
Blackout - A zero voltage condition lasting for more than two cycles. Same as a power failure
Overcharge - The forcing of current through a cell after all the active material has been converted to the charged state, that is, continued charging after reaching 100 percent state-of-charge.
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.
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.
