AC ammeter
Date: circa 1900
Inventory Number: 1997-1-0326
Classification: Ammeter
Subject:
Maker: Weston Electrical Instrument Corporation (founded 1888)
Cultural Region:
Place of Origin:
Dimensions:
20 × 20.5 × 9.3 cm (7 7/8 × 8 1/16 × 3 11/16 in.)
Description:
An ammeter consisting of a wooden box with an arc-shaped window containing a scale that goes from 0 to 15 amperes. The scale is nonlinear with the intervals between amps longer as one moves up the scale. Over the scale moves a pointer held by two aluminum wires that originate at a moving vane at the center of a mechanism composed of a metal tape coil and a hair spring. (Normally hidden from view by the box). There is a reflecting band under the scale.
The box has two electrical connectors on top, and it has a leather strap on its right side.
The box has two electrical connectors on top, and it has a leather strap on its right side.
Signedplaque: MADE BY THE / WESTON ELECTRICAL INSTRUMENT CORP / NEWARK, N.J. / U.S.A. / PATENTED / JAN [illegible] 95, MAR 25 98, OCT 3[5?] 98 / OTHER PATENTS PENDING / MODEL 155 / No. 65945
Inscribedbelow scale: AMPERES A.C. / AMPERES FOR FULL SCALE=15
below screw: CORRECTION
written with black ink over green background: E 1981 / N(U?).S.G. / STOCK
below screw: CORRECTION
written with black ink over green background: E 1981 / N(U?).S.G. / STOCK
FunctionThis is an ammeter for AC current. It most likely works by deflection of its needle by a magnetic field generated at a coil through which the current to be measured passes.