# US 8,786,273 B2 · System and method for improving accuracy of high voltage phasing voltmeters > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,273 B2 - Document ID: US8786273B2 - Status: Granted - Kind: B2 - Application number: 12/888,589 - Filed: 2010-09-23 - Published: 2012-03-29 - Granted: 2014-07-22 - Earliest claimed: 2010-09-23 - Assignees: Honeywell International Inc. - Applicants: Adishesa Cs; Anil Nagpal - Inventors: Adishesa Cs; Anil Nagpal - Web page: https://patentgrep.com/patent/US8786273B2 ## CPC - G01R 15/16: using capacitive devices - G01R 1/06777: {High voltage probes} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A high voltage phasing voltmeter comprises first and second probes. Each probe comprises an insulated handheld shield supporting an electrode for contacting a high voltage electrical conductor. The electrode is connected in series with a resistor and a capacitor. A meter comprises a housing enclosing an electrical circuit for measuring phasing voltage. The electrical circuit comprises an input circuit for connection to the first and second probes and an amplifier connected between the input circuit and a display. The amplifier measures voltage across the electrodes to provide an indication on the display. ## Claims ### Claim 1 A high voltage phasing voltmeter comprising: first and second probes, each comprising an insulated handheld shield supporting an electrode for contacting a high voltage electrical conductor, the electrode being connected in series with a resistor and a capacitor; and a meter comprising a housing enclosing an electrical circuit for measuring phasing voltage, the electrical circuit comprising an input circuit for connection to the first and second probes, the input circuit comprising a biasing circuit, and an amplifier connected between the input circuit and a display, the amplifier comprising an active compensation circuit with high common mode rejection to eliminate common mode parasitic noise effects and developing an output representing voltage difference between the first and second probes to provide an indication on the display. ### Claim 2 (depends on 1) The high voltage phasing voltmeter of claim 1 wherein each shield comprises an elongate tube and wherein an inner surface of each tube included a conductive coating. ### Claim 3 (depends on 2) The high voltage phasing voltmeter of claim 2 wherein the conductive coating is electrically connected to a meter ground circuit. ### Claim 4 (depends on 1) The high voltage phasing voltmeter of claim 1 wherein the housing is integral with the handheld shield for one of the probes. ### Claim 5 (depends on 4) The high voltage phasing voltmeter of claim 4 further comprising a cable electrically connected between the electrical circuit and the other of the probes. ### Claim 6 (depends on 1) The high voltage phasing voltmeter of claim 1 wherein the amplifier comprises a common mode rejection differential input amplifier. ### Claim 7 (depends on 6) The high voltage phasing voltmeter of claim 6 wherein the amplifier has unity gain. ### Claim 8 (depends on 1) The high voltage phasing voltmeter of claim 1 wherein the electrical circuit comprises a range selection circuit between the amplifier and the display. ### Claim 9 (depends on 8) The high voltage phasing voltmeter of claim 8 wherein the range selection circuit comprises a variable gain amplifier circuit. ### Claim 10 (depends on 1) The high voltage phasing voltmeter of claim 1 wherein the electrical circuit comprises a battery powered circuit. ### Claim 11 A high voltage portable phasing voltmeter comprising: a first probe comprising an elongate insulated shield having a handle portion at one end, an electrode extending from a distal end of the shield for contacting a high voltage electrical conductor, and a high impedance circuit in the shield comprising a resistor and a capacitor connected in series with the electrode; a second probe comprising an elongate insulated shield having a handle portion at one end, an electrode extending from a distal end of the shield for contacting a high voltage electrical conductor, and a high impedance circuit in the shield comprising a resistor and a capacitor connected in series with the electrode; and a meter comprising a housing enclosing an electrical circuit for measuring phasing voltage, the electrical circuit comprising an input circuit, for connection to the first and second probe high impedance circuits, the input circuit comprising a biasing circuit, and an amplifier connected between the input circuit and a display, the amplifier comprising an active compensation circuit with high common mode rejection to eliminate common mode parasitic noise effects and developing an output representing voltage difference between the first and second probes measuring voltage across the electrodes to provide an indication on the display. ### Claim 12 (depends on 11) The high voltage phasing voltmeter of claim 11 wherein each shield comprises an elongate tube and wherein an inner surface of each tube included a conductive coating. ### Claim 13 (depends on 12) The high voltage phasing voltmeter of claim 12 wherein the conductive coating is electrically connected to a meter ground circuit. ### Claim 14 (depends on 11) The high voltage phasing voltmeter of claim 11 wherein the housing is integral with the handle portion of the first probe. ### Claim 15 (depends on 14) The high voltage phasing voltmeter of claim 14 further comprising a cable electrically connected between the electrical circuit and the second probe. ### Claim 16 (depends on 11) The high voltage phasing voltmeter of claim 11 wherein the amplifier comprises an amplifier with high common mode rejection ratio. ### Claim 17 (depends on 16) The high voltage phasing voltmeter of claim 16 wherein the amplifier has unity gain. ### Claim 18 (depends on 11) The high voltage phasing voltmeter of claim 11 wherein the electrical circuit comprises a range selection circuit between the amplifier and the display. ### Claim 19 (depends on 18) The high voltage phasing voltmeter of claim 18 wherein the range selection circuit comprises a variable gain amplifier circuit. ### Claim 20 (depends on 11) The high voltage phasing voltmeter of claim 11 wherein the electrical circuit comprises a battery powered circuit.