Page:Popular Science Monthly Volume 90.djvu/87

 A Miniature Power- Plant for the Home

��All the essential elements of a great commercial supply plant are incorporated in simplified form

��A COMPLETE power-plant supplying a home with all the electricity it needs is in reality a miniature power- house hke that used to supply electricity to thousands of homes. It must contain all the essential elements of such a'power-house but on a smaller and simplified scale.

Still, a gasoline-engine and a dynamo are not simple things. Formerly, only a skilled electrician and mechanic was able to run his own plant without trouble. With the further development of the individual electric-plant, however, it has finally been made practically automatic in operation and so simple that a child can operate it.

One of the first things simplified was the gas-engine. It is now automatically oiled. Because it has a self-starter, it is started by the mere ,

closing of a °''"°^^ switch. The next improve- ment was the combining of the engine and dynamo into one apparatus. Formerly they were separate machines con- nected by a long belt. Now they are mounted on the same shaft. Lastly stor- age-batteries are now used, which not only

enable a man to run his engine-dynamo set during the odd times he is at lei- sure, but have greatly reduced the cost of producing the electricity.

The storage -batteries serve the purpose of storing the electricity until the time when it will be wanted, in much the same way as a reservoir -tores water. After they have been filled, the batteries will hold enough electricity to last for four or five days of service. When they are empty, it is necessary only to start up the engine and dynamo again. The engine drives the dynamo and when it revolves, just

���as when the great dynamos oi a large power- house revolve, electricity is produced. The dynamo then feeds the electricity into the storage-batteries to be again stored until wanted. It has been made easy to tell when the batteries are empty ; for at such a time an instrument on the switch-board which is mounted on the top of the dynamo, points to the word "empty."

When running normally, the plant can light fifteen sixteen-candlepower lamps, or it can run two small motors of one-sixth horsepower each. It can do this continu- ously for eight hours. If it is desired to use them longer, it is necessary only to close the switch of the self-starter of the engine- dynamo set. The plant can also be used to light thirty-two lamps, or fifteen lamps and two motors, by start- ing up the engine- dynamo set and run- ning it continuously. The cost of gaso- line for the engine is only twenty- five cents a day. When natural-gas can be used in the engine, this cost is still further reduced to eight cents a day.

��Oil-less bearing

����Above: Cross-section of the simplified engine-dynamc se^ Below : The set complete, with the batteries

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