# US 2019/0317138 A1 · Enhanced Circuit and Method for Detecting Hazardous Foreign Voltages on Conductors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0317138 A1 - Document ID: US20190317138A1 - Status: Published application - Kind: A1 - Application number: 15/963,593 - Filed: 2018-04-26 - Published: 2019-10-17 - Earliest claimed: 2018-04-13 - Assignees: Power Solutions, Inc. - Applicants: Power Solutions, Inc. - Inventors: Mel Thrasher; Brandon Thrasher - Web page: https://patentgrep.com/patent/US20190317138A1 ## CPC - G01R 19/155: Indicating the presence of voltage - G01R 1/06788: {Hand-held or hand-manipulated probes, e.g. for oscilloscopes or for portable test instruments (end pieces terminating in a probe H01R11/18)} - G01R 15/16: using capacitive devices - G01R 19/16561: {in hand-held circuit testers (see also G01R19/155)} - G01R 19/16576: {comparing DC or AC voltage with one threshold (G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533 and G01R19/1659 take precedence)} - G01R 19/2513: {Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging} - G01R 19/2516: {Modular arrangements for computer based systems; using personal computers (PC's), e.g. "virtual instruments"} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A method of detecting the presence of a hazardous foreign voltage on a conductor includes the steps of sensing an electric field in the vicinity of the conductor with a first non-contact conductive sensor and sensing the electric field in the vicinity of the conductor with a second non-contact conductive sensor spaced a predetermined distance from the first non-contact conductive sensor. The difference between the electric field sensed by the first conductive sensor and the electric field sensed by the second conductive sensor is determined. The first conductive sensor preferably is shaped as a truncated spheroid. If the difference is less than a predetermined threshold, the sensed electric field is ignored as being induced by a distant source. If the difference is greater than a predetermined threshold, the electric field sensed by the first and second conductive sensors is considered to be indicative of the presence of a foreign voltage on the conductor. In that event, at least one alarm is activated as an alert to the presence of a foreign voltage on the conductor. ## Claims ### Claim 1 A method of detecting the presence of a hazardous alternating current foreign voltage on a conductor, the method comprising the steps of: (a) sensing an alternating electric field in the vicinity of the conductor with a first non-contact conductive sensor having a generally truncated spheroidal shape; (b) sensing the alternating electric field in the vicinity of the conductor with a second non-contact conductive sensor spaced a predetermined distance from the first non-contact conductive sensor and being shaped as a sleeve; (c) generating an alternating difference signal that is proportional to the difference between the alternating electric field sensed by the first conductive sensor and the alternating electric field sensed by the second conductive sensor; (d) if the alternating difference signal generated in step (c) exhibits a peak that is less than a predetermined threshold, considering the electric filed sensed by the first and second conductive sensors not to be indicative of the presence of a foreign voltage on the conductor and ignoring the difference signal generated in step (c); (e) if the alternating difference signal generated in step (c) exhibits a peak that is greater than a predetermined threshold, considering the electric field sensed by the first and second conductive sensors to be indicative of the presence of a foreign voltage on the conductor; and (f) activating at least one alarm if the presence of a foreign voltage on the conductor is indicated in step (e). ### Claim 2 (depends on 1) The method of claim 1 wherein the predetermined distance in step (b) is between about 80 mils and about 120 mils. ### Claim 3 (depends on 2) The method of claim 2 wherein the predetermined distance in step (b) is 100 mils. ### Claim 4 (depends on 1) The method of claim 1 further comprising determining a frequency of the difference signal generated in step (c) and ignoring difference signals below a predetermined threshold frequency. ### Claim 5 (depends on 4) The method of claim 4 wherein the predetermined frequency is about 35 hertz. ### Claim 6 (depends on 1) The method of claim 1 further comprising filtering the alternating difference signal generated in step (c) with a low pass filter to remove components of the alternating difference signal above a predetermined frequency. ### Claim 7 (depends on 6) The method of claim 6 wherein the predetermined frequency corresponds to radio wave and microwave frequencies. ### Claim 8 (depends on 1) The method of claim 1 wherein step (d) comprises repeatedly sampling the difference signal, storing the highest value sampled, storing a zero crossing value sampled, and subtracting the highest value from the zero crossing value to determine the peak of the difference signal. ### Claim 9 (depends on 8) The method of claim 8 wherein the zero crossing value is determined when a sample of the difference signal falls below a predetermined threshold. ### Claim 10 (depends on 9) The method of claim 9 wherein the predetermined threshold is about 4. ### Claim 11 (depends on 1) The method of claim 1 wherein step (f) comprises activating a bar graph indicator to display the approximate magnitude of the sensed alternating foreign voltage. ### Claim 12 (depends on 11) The method of claim 11 wherein the bar graph indicator is an LED bar graph. ### Claim 13 (depends on 12) The method of claim 12 wherein step (f) comprises activating an audible alarm. ### Claim 14 (depends on 13) The method of claim 13 wherein step (f) comprises activating a tactile alarm. ### Claim 15 (depends on 1) An electronic circuit configured to carry out the method of claim 1. ### Claim 16 (depends on 1, 15) The electronic circuit of claim 15 wherein the circuit includes a microprocessor programmed to carry out the steps of claim 1. ### Claim 17 (depends on 16) The electronic circuit of claim 16 wherein the circuit includes an instrument amplifier configured to generate the difference signal and at least one operational amplifier configured to low pass filter the difference signal before the signal is presented to the microprocessor for analysis. ### Claim 18 (depends on 15) The electronic circuit of claim 15 wherein the first sensor has a hemispherical shape with a truncated end adjacent the second senor with the distance D between the truncated of the first sensor and the second sensor is between 80 mils and 120 mils. ### Claim 19 (depends on 18) The electronic circuit of claim 18 wherein the distance D is 100 mils.