Rectifiers Replace Power Chargers
A change has been made in the fire and police alarm systems of Indianapolis, Ind., which has greatly increased its efficiency.
Thirty new General Electric copper oxide rectifiers have been installed at fire alarm headquarters. The copper oxide rectifiers are supplied with 3-phase alternating current, each phase operating ten rectifiers. The three bulbs mounted at the top of the panel board are connected, one to each phase. In the event of one, two or three phases failing, the light or lights will go out.
Besides this protection, each rectifier is connected to another small bulb at the top of the panel board. There are thirty of these small bulbs in all, one for each rectifier. If the current supply should be cut off from any individual rectifier, the small bulb connected to that particular rectifier will light and a relay will cause the buzzer at the top of the panel to sound a warning.
Before these copper oxide rectifiers were installed, the batteries were charged from direct current power lines requiring resistors to step down the voltage. Two sets of batteries had to be used—one working while the other was being charged. With the new installation, duplicate sets of batteries are eliminated.
The Indianapolis installation is in charge of Thomas T. Haefling, Superintendent of Police and Fire Alarm Systems.