electrostatic voltmeter
Inventory Number2012-1-0042
ClassificationVoltmeter
Subject
Maker
Rawson Electrical Instrument Company
1918 - 1968
Cultural Region
Place of Origin
Place of Use
Dimensions16.5 × 19.5 × 18.8 cm (6 1/2 × 7 11/16 × 7 3/8 in.)
Material
DescriptionSquare walnut case with flat leather handle and hinged lid.
Inside is the instrument, with a bakelite casing. Fan-shaped window at bottom of the panel, with the Rawson standard pointer (with a double, o-shaped section over the mirror) with a reflective band under the scale.
Tripple scale, top sclae non-linear , 0-120 volts, middle linear scale written in 0-600 volts, bottom linear scale 0-1200 volts.
Above the scale on left is button labeled “ZERO CHECK” Raised cylindrical piece with "CLAMP" dial, arrow on “CLAMP “ dial and labeled underneath “UNCLAMP BEFORE APPLYING VOLTAGE”. On right side are two black capped binding post, upper one labeled “120” lower on labeled “COMMON” and “LOW”.
Inside is the instrument, with a bakelite casing. Fan-shaped window at bottom of the panel, with the Rawson standard pointer (with a double, o-shaped section over the mirror) with a reflective band under the scale.
Tripple scale, top sclae non-linear , 0-120 volts, middle linear scale written in 0-600 volts, bottom linear scale 0-1200 volts.
Above the scale on left is button labeled “ZERO CHECK” Raised cylindrical piece with "CLAMP" dial, arrow on “CLAMP “ dial and labeled underneath “UNCLAMP BEFORE APPLYING VOLTAGE”. On right side are two black capped binding post, upper one labeled “120” lower on labeled “COMMON” and “LOW”.
Signedprinted on face of meter: (left) TYPE 508 / No. 4332 / (right) PATENTED / MAY 15, 1923 / APRIL 15, 1924 / MAR. 3, 1925 / OTHERS PENDING / MAY 15, 1928 / RAWSON ELECTRICAL INSTRUMENT CO., INC. / CAMBRIDGE, MASS. / ELECTROSTATIC VOLTMETER
FunctionA voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit.
An electrostatic voltmeter is one in which the voltage to be measured is applied between fixed and movable metal vanes; the resulting electrostatic force deflects the movable vane against the tension of a spring.
An electrostatic voltmeter is one in which the voltage to be measured is applied between fixed and movable metal vanes; the resulting electrostatic force deflects the movable vane against the tension of a spring.
Weston Electrical Instrument Corporation
Date: 1920-1930
Accessories: standardization card from the A.S. Mancib Co.
Object number: WJ0951
Weston Electrical Instrument Corporation
Date: 1900-1930
Accessories: standardization certificate on inner surface of lid
Object number: 1997-1-1183
Weston Electrical Instrument Corporation
Date: circa 1913
Object number: 1997-1-0328
