IEEE 1115-2014 pdf free.IEEE Recommended Practice for Sizing Nickel-Cadmium Batteries for Stationary Applications.
Noncontinuous loads for starting emergency generators, lire pumps. and other equipment powered by internal-combustion engines represent a special sizing case for which the recommended procedures in this document are not well suited. Annex D covers an industry-standard method for sizing nickel-cadmium batteries for engine-starting duties.
4.2.4 Other considerations
The lists of typical loads appearing in 4.2.2 and 4.2.3 are not a full catalog of the dc loads at any particular installation. Loads applied to the battery are normally typed as constant power. constant resistance, or constant currcnt. However, for sizing purposcs. 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 11).
4.3 Duty cycle diagram
4.3.1 General
A duty cycle diagram showing 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 as either powcr or current cxpcctcd 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.
4.3.2 Known loads
Loads that have inception and shutdown times that are known are plotted on the duty cycle 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 rcmaindcr of the duty cycle.
4.3.3 Random loads
Noncontinuous 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. 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 I (see also 6.5.5).IEEE 1115 pdf free download.