IEEE 946-2004 pdf download IEEE Recommended Practice for the Design of DC Auxiliary Power Systems for Generating Stations
3. Definitions
For the purposes of this recommended practice, the following terms and definitions apply. TheAuthoritative Dictionary of IEEE Standards (B27 should be referenced for terms not defined in thisclause.
3.1 battery capacity: The amp-hours available in an installed battery as measured by test. This ismeasured, normally after an equalize charge, by a performance or modified performance test. The batterycapacity may be larger or smaller than the rated capacity and is expressed as a per cent of rated capacity fora given duration. For lead acid batteries, this is due to degradation of the grid, connections, welds, pelletinterface to the grid, crystal surface contact interface of the lead oxides, wet surface interface between thelead oxide and the electrolyte, electrolyte specific gravity, and transport resistance of the hydrogen andoxygen between the positive and negative plates. Since the factors which affect battery performance arevaried. the measured battery capacity at a long duration may differ from the measured capacity at a shortduration.
3.2 battery rated capacity: The rated amp-hours available in a battery at 100% charge. This is establishedvia “$or fan curves by a manufacturer’s test of a limited sample of cells using the interconnectinghardware supplied with the standard installation. The rated amp-hours may differ as a function of thedischarge duration, long duration discharges typically utilizes the available material more effectively.NOTE-See IEEE Std 485 for an example of the manufacturer’s sizing curves.3.3 battery state of charge: A factor between 0 and 100. It establishes the available amp-hours bymultiplying the state of charge times the battery capacity times the battery rated capacity for a specifieddischarge duration. The battery state of charge reflects the conversion or restoration of lead sulfate to leadoxide after a discharge.
4.General
4.1 Description and operation
All power generating stations require dc auxiliary power systems to operate those dc components that mustbe available should a loss of ac power occur. Some examples of such components are auxiliary motorscircuit breakers, relays, solenoids, and inverters. The dc source(s) may be one common battery for bothpower and control or two separate batteries: one for power and another for control and instrumentation.Separate batteries are recommended for special services such as for engine (cranking) starting.
IEEE 946-2004 pdf download
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