Power source (safety) - Power source for loads defined as critical by applicable safety regulations. This supply must not be affected by a mains failure and is generally separate from other supplies.
Micro-outage (or micro-interruption) - Total loss in the supply of power for 10 ms.
Bypass (manual) - Manually-operated switch used to supply the load via direct connection to utility power during servicing of the UPS system.
IR Drop - A voltage drop associated with the electrical resistance (R) of a battery or current flow (I). The voltage drop is the product of the current (in amperes) and the resistance (in ohms).
Cutoff Voltage (also see End Voltage) - The battery voltage at which the discharge is terminated. The cutoff voltage is specified by the battery manufacturer and is generally a function of discharge rate.
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.
Top-Up Charge - A low rate charge following the main charge, designed to ensure maximum capacity.
