Description

This demand indicator consists of a hinged, key-shaped cast iron case. The top part of the case has “Wright Demand Indicator / General Electric Schenectady USA” embossed on it. The bottom part of the case is thinner than the top, and has a glass window through which a glass tube set in front of a sheet with graduation marks. Opening the instrument reveals two glass reservoirs that connect to the u-shaped glass tube within (only one legs of the tube is visible in the window). There is a metal band around one of the tubes, and this is in turn connected to the porcelain-insulated terminals on either side of the instrument.

This demand indicator registered the maximum ampere demand in an electrical circuit. This one was used in the Allstator Machine Company in Hamilton, Ohio.