CHAPTER XLV
STORAGE BATTERY SYSTEMS
Storage batteries are used for many purposes, such as to supply current for electric vehicles, gas engine ignition, lighting, and in connection with power stations and distribution work.
The latter is an important field, the storage battery being used in connection with the power station for the following purposes:
1. To carry the peak load, during hours of maximum demand;
2. To carry the entire load during hours of minimum demand, or for a short time in case of emergency;
3. To act as an equalizer;
4. For regulation of load and voltage;
5. As compensation for feeder drop;
6. As a preventive against shut downs.
In almost every electric lighting plant there are long periods during the day and late at night when the number of lamps lighted is so small that it may not pay to run the generating machinery. In such cases, storage batteries may usually be used to advantage to aid in carrying the maximum load and to supply the entire current at minimum load as illustrated in [fig. 1,179]. In other words, batteries are substituted for a certain portion of the machinery plant or are used in place of the latter.
Ques. What provision must be made in power plants when storage batteries are not used?
Ans. The capacity of the generating machinery must be sufficient for the heaviest overloads which may occur, and it must be operated continuously for 24 hours a day in the majority of central stations supplying current for lighting and power.
Ques. What results are obtained with this method of working?
Ans. The engines working under very variable loads, not only operate at low efficiency, but are continually subjected to severe mechanical strains.