Frequency Variation - A change in frequency of more than 3 Hz.
Parallel - Term used to describe the interconnection of cells or batteries in which all the like terminals are connected together. Results in increased capacity.
Bypass (manual) - Manually-operated switch used to supply the load via direct connection to utility power during servicing of the UPS system.
High Voltage Spike - Rapid voltage peak up to 6000 volts with a duration of 100mS to 1/2 cycle.
Memory Effect - A phenomenon in which a cell or battery operated in successive cycles to the same, but less than full, depth of discharge temporarily loses the rest of its capacity at normal voltage levels.
Earthing system IT - Earthing system in which the neutral is isolated from the earth or connected to the earth via a high impedance and the various exposed conductive parts are connected to the earth via individual earthing circuits. An alarm must signal the appearance of a first insulation fault. The installation must be de-energized immediately in the event of a second insulation fault.
Nominal Voltage - The characteristic operating voltage or rated voltage of a battery.
