General Electric current indicator

Description (Brief):

This ammeter consists of a black, glass top case. Marked: "Current Indicator / No. 8792 / Capacity 600 Amperes / Patented Oct. 22. 1889 / .General Electric Co. / Thomson-Houston System". This type ammeter was patented in 1889, developed by the Thomson-Houston Co., Lynn, Mass.; however, this particular modal was made at a later date by the General Electric Co. after it was formed by the merging of the Thomson-Houston Co. and others, [in 1892]. The current to be measured passes through a single turn conductor in which is pivoted eccentrically a soft iron movement controlled by gravity. As a result of the eccentricity, the current tends to rotate the iron piece into a position nearer to the conductor, which produces a scale deflection as a measure of the current. In all ammeters of this general ┬Ětype it was necessary to bring the entire current to be measured to the switchboard and into the instrument, regardless of its magnitude . This necessity was eliminated and a great saving of copper effected, when the heavy current shunt was developed by Dr. Edward Weston and used with his permanent magnet movable coil type instrument.

Date Made: ca 1893

Maker: General Electric Company

Location: Currently not on view

See more items in: Work and Industry: Electricity


Exhibition Location:

Credit Line: from Weston Electrical Instrument Corp., thru John H. Miller

Data Source: National Museum of American History

Id Number: EM.313278Catalog Number: 313278Accession Number: 181342

Object Name: AmmeterOther Terms: Ammeter; Measuring Devices

Physical Description: wood, glass (case material)Measurements: overall: 4 1/4 in x 15 in x 11 in; 10.795 cm x 38.1 cm x 27.94 cm


Record Id: nmah_710147

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.