Westinghouse style 35246 Precision Ammeter
date: label: date made
content: 1908
name: label: maker
content: Westinghouse Electric and Manufacturing Company
notes: label: Description (Brief)
content: This instrument consists of a precision ammeter of 50 ampere capacity enclosed in a polished mahogany container in a leather case, marked Westinghouse Elec. & Mfg. Co., Pittsburgh, Pa., Serial #45536. " This is a torsion head spring controlled ammeter consisting essentially of a Kelvin balance type of system with two moving coils each acting between a pair of fixed coils. The electrodynamic force between two sets of coils carrying the current is balanced against a spring controlled by a torsion head which moves over a graduated dial. For precision purposes it was necessary to make corrections throughout the scale by means of a calibration curve for the reason that Hook’s Law of the spring torque against deflection is not perfect. For the same reason as for the Siemens instrument, currents which are not steady are difficult to measure. Matches catalog #313275.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
creditLine: label: Credit Line
content: from Weston Electrical Instrument Corp., thru John H. Miller
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.313276
label: accession number
content: 181342
label: catalog number
content: 313276
objectType: label: Object Name
content: Ammeter
label: Other Terms
content: Ammeter; Measuring Devices
physicalDescription: label: Physical Description
content: metal (overall material)
label: Measurements
content: overall: 8 1/2 in x 10 1/2 in x 9 in; 21.59 cm x 26.67 cm x 22.86 cm