Issue 10 and Volume 24.

MOTOR GENERATORS FOR CHICAGO’S FIRE ALARM SYSTEM. Chicago, Ill., where the Gamewell fire alarm system is installed, has a closed circuit system—as is usual in all large cities. By that is meant a circuit through which a small amount of current is kept constantly flowing—one on which the alarm boxes are placed in series, and where the momentary opening of the circuit by a street signal box causes the fire alarm signals to be turned in. In order to insure absolute reliability and constancy of the current supply, storage batteries were substituted for the gravity batteries. In order also to make provision for the supply of the fire alarm circuits while the batteries are being charged, a set of motor generators has been put in, adapted for running from c no-volt circuit. Each one of these motor generators is a 110-volt motor connected directly by means of a flexible coupling…

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