IEEE 485-2010 pdf download

IEEE 485-2010 pdf download.IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications
4.2.3 Momentary loads
Momentary loads can occur one or more times during the duty cycle but are of short duration, not exceeding 1 minute at any occurrence. Although momentary loads may exist for only a fraction of a second, it is common practice to consider each load will last for a full minute because the battery voltage drop after several seconds often determines the battery’s 1 minute rating. When several momentary loads occur within the same 1 minute period and a discrete sequence cannot be established, the load for the 1 minute period should be assumed to be the sum of all momentary loads occurring within that minute. If a discrete sequence can be established, the load for the period should be assumed to be the maximum load at any instant. Sizing for a load lasting only a fraction of a second, based on the battery’s 1 minute performance rating, results in a conservatively sized battery. Consult the battery manufacturer for ratings of discharge durations less than 1 minute. Typical momentary loads are as follows:
a) Switchgear operations
b) Motor-driven valve operations (stroke time <1 minute)
c) Isolating switch operations
d) Field flashing of generators
e) Motor starting currents
f) Inrush currents
4.2.4 Other considerations The preceding lists of typical loads are not a full catalog of the dc loads at any one installation. The loads applied to the battery are normally categorized as constant power, constant resistance, or constant current. However, for sizing purposes, the loads are treated as constant power or constant current. The designer should review each system carefully to be sure all possible loads and their variations are included (see Annex B). If the loads are solely constant power loads, sizing as described in Annex E is appropriate and may simplify the sizing process.
4.3 Duty cycle diagram A duty cycle diagram showing the total load at any time during the cycle is an aid in the analysis of the duty cycle. To prepare such a diagram, all loads (expressed in either current or power) expected during the cycle are tabulated along with their anticipated inception and shutdown times. The total time span of the duty cycle is determined by the requirements of the installation.
4.3.1 Defined loads Loads whose inception and shutdown times are known are plotted on the diagram as they would occur. If the inception time is known, but the shutdown time is indefinite, it should be assumed that the load will continue through the remainder of the duty cycle.
4.3.2 Random loads Loads that occur at random should be shown at the most critical time of the duty cycle in order to simulate the worst-case load on the battery. These may be noncontinuous or momentary loads as described in 4.2.2 and 4.2.3. To determine the most critical time, it is necessary to size the battery without the random load(s) and to identify the section of the duty cycle that controls battery size. Then the random load(s) should be superimposed on the end of that controlling section as shown in Figure 1 (see 6.3.4).
5. Cell selection This clause summarizes some factors that should be considered in selecting a cell design for a particular application. Various cell designs have different charge, discharge, and aging characteristics. Refer to IEEE Std 1184 TM -2006, Annex D of this document, and vendor literature for a discussion of cell characteristics.
The following factors should be considered in the selection of the cell:
a) Physical characteristics, such as dimensions and weight of the cells, container material, intercellconnectors, and terminals
b) Planned life of the installation and expected service life of the cell
c) Frequency and depth of discharge
d) Ambient temperature (Note that sustained high ambient temperatures result in reduced battery life. See IEEE Std 484 TM -2002 and IEEE Std 1187 TM -2002.)
e) Charging characteristics
f) Maintenance requirements
g) Cell orientation requirements
h) Ventilation requirements
i) Seismic characteristics
j) Spill management.IEEE 485 pdf download.IEEE 485-2010 pdf download