Motion picture handbook; a guide for managers and operators of motion picture theatres ([c1916])

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360 MOTION PICTURE HANDBOOK Page 351. On the face of the front casting is a hand-wheel which operates a single-pole knife switch, located on the I * | opposite side of the casting. When I I I I this switch is thrown so that its finger II j points toward "high" you are getting II j the maximum amperage, approxiII jjf mately 65. When it points to "me 3?r""T^feA»Hfc^ I dium" you are getting a medium amperage, and when it points to "low" you are getting the lowest amperage the transformer will supply. The inductor is designed for a maximum of 65 amperes on "high," 54 on '"medium," and 45 on "low" when used on 110 or 220 volts, it being, of course, understood that you cannot use 110 volt inductor on 220, or a 220 on 110. In other words, you must have an inductor suitable to the voltage of your supply; also it must be Figure 1/1. suitable to the cycle of the current you use, though the inductor may be used on voltage ranging 10 per cent below to 10 per cent, above that for which it is rated, but in one case there will be a corresponding increase, and in the other a decrease in its rated amperage. The inductor is designed for a maximum temperature rise of 50 degrees Fahrenheit above the surrounding atmosphere, and ordinarily its temperature will not exceed 30 degrees in excess of the surrounding air. It occupies 12 x 14 inches floor space, is 19 inc'hes high, and weighs approximately 100 pounds. Its efficiency rating will compare favorably with other machines of its kind. THE HALLBERG ECONOMIZER The "Hallberg" A. C. to A. C. economizer is nothing more or less than a transformer of the semi-constant current type, specially designed for use in moving picture projection arc circuits, taking A. C. at line voltage and delivering A. C. at .arc voltage. "Semi-constant" means that it will receive supply at a fixed potential, but will deliver at the arc practically steady amperage flow, regardless, within reasonable limits, of the length of the arc. The device consists of a continuous, rectangular core, on one leg of which is wound a primary coil, and on the opposite