IEEE 485-1997 pdf download IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications
3. Definitions
The following definitions apply specifically to this recommended practice. For other definitions, see IEEFStd 100-1996.2
3.1 battery duty cycle: The loads a battery is expected to supply for specified time periods
3.2 cell size: The rated capacity of a lead-acid cell or the number of positive plates in a cell
3.3 equalizing charge: A prolonged charge, at a rate higher than the normal float voltage, to correct anyinequalities of voltage and specific gravity that may have developed between the cells during service.
3.4 full float operation: Operation of a dc system with the battery, battery charger, and load all connected inparallel and with the battery charger supplying the normal dc load plus any charging current required by thebattery. (The battery will deliver current only when the load exceeds the charger output.)
3.5 period: An interval of time in the battery duty cycle during which the load is assumed to be constant forpurposes of cell sizing calculations.
3.6 rated capacity (lead-acid): The capacity assigned to a cell by its manufacturer for a given dischargerate, at a specified electrolyte temperature and specific gravity, to a given end-of-discharge voltage
3.7 valve-regulated lead-acid (VRLA) cell: A lead-acid cell that is sealed with the exception of a valve thatopens to the atmosphere when the internal gas pressure in the cell exceeds atmospheric pressure by a preselected amount.VRLA cells provide a means for recombination of internally generated oxygen and thesuppression of hydrogen gas evolution to limit water consumption.
3.8 vented battery: A battery in which the products of electrolysis and evaporation are allowed to escapereely to the atmosphere. These batteries are commonly referred to as “flooded””
4. Defining loads
4.1 General considerations
The duty cycle imposed on the battery by any of the conditions described herein will depend on the dcsystem design and the requireents of the installation. The battery must supply the dc power requirementswhen the following conditions occur:
aLoad on the dc system exceeds the maximum output of the battery charger:6)Output of the battery charger is interrupted;
cAC power is lost (may result in a greater de power demand than b) above].
The most severe of these conditions, in terms of battery load and duration, should be used to determine thebattery size for the installation.
4.2 Load classication
The individual dc loads supplied by the battery during the duty cycle may be classied as continuous or noncontinuous. Noncontinuous loads lasting 1 min or less are designated “momentary loads” and should be given special consideration (see 4.2.3).
IEEE 48-1997 pdf download
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