# US 9,753,059 B2 · Detection of geomagnetically-induced currents with power line-mounted devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,753,059 B2 - Document ID: US9753059B2 - Status: Granted - Kind: B2 - Application number: 14/940,910 - Filed: 2015-11-13 - Published: 2016-03-10 - Granted: 2017-09-05 - Earliest claimed: 2014-02-07 - Assignees: Smart Wires Inc. - Applicants: Smart Wires Inc. - Inventors: Frank Kreikebaum; Paul Phillipsen; Stuart E. Ross; Yuli Starodubtsev - Web page: https://patentgrep.com/patent/US9753059B2 ## CPC - G01R 19/0092: {Measuring current only} - G01R 15/202: {using Hall-effect devices (Hall elements in arrangements for measuring electrical power G01R21/08)} - G01R 15/207: {Constructional details independent of the type of device used} - G01R 21/08: by using galvanomagnetic-effect devices, e.g. Hall-effect devices - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A device for use in a power transmission system to sense GICs. The device may be a part of a reactance-injecting device on a power line, it may be a standalone device, or it may be a part of another type of device. The device may include a sensor to sense magnetic fields (e.g., a Hall effect sensor). The sensor may be positioned in the air gap of a magnetic core formed concentrically around the power line. The signal from the sensor may be converted to a digital signal and separately processed to determine the magnitude of the AC current and the magnitude of the DC (or quasi-DC) current. If the output signal of another A/C current sensor is available, that output signal may be used to adjust/calibrate the determined magnitude of the DC current. The sensor may communicate with other devices in a network to provide GIC information. ## Claims ### Claim 1 A device for monitoring geomagnetically-induced currents in a power transmission line, comprising: a magnetic core disposed about a power transmission line, the core being configured to provide an air gap therein, wherein with the exception of the air gap, the magnetic core completely surrounds the power transmission line; a magnetic sensor positioned in the air gap to sense magnetic fields and produce an output signal representative of the magnetic fields; a signal processing unit that receives the output signal and determines the magnitude of a geomagnetically-induced current in the power transmission line therefrom; and an injecting unit for injecting reactance into the power transmission line. ### Claim 2 (depends on 1) A device as claimed in claim 1, further including an upper housing and a lower housing that are configured for placement around the power transmission line and for attachment to each other to contain the core, sensor, and signal processing unit therein. ### Claim 3 (depends on 1) A device as claimed in claim 1, wherein the core includes at least two separate core portions. ### Claim 4 (depends on 1) A device as claimed in claim 1, wherein the core includes at least three separate core portions. ### Claim 5 (depends on 4) A device as claimed in claim 4, wherein one of the three separate core portions is configured to extend approximately 180 degrees around the power transmission line. ### Claim 6 (depends on 4) A device as claimed in claim 4, wherein two of the three separate core portions are each configured to extend only approximately 90 degrees around the power transmission line. ### Claim 7 (depends on 1) A device as claimed in claim 1, wherein the signal processing unit processes signals at or near DC with a DC processing portion. ### Claim 8 (depends on 7) A device as claimed in claim 7, wherein the DC processing portion includes a low pass filter. ### Claim 9 (depends on 7) A device as claimed in claim 7, wherein the DC processing portion includes a unit for determining the mean of the signals and providing a DC component signal representative thereof. ### Claim 10 (depends on 1) A device as claimed in claim 1, wherein the signal processing unit separately processes AC signals and signals at or near DC with an AC processing portion and a DC processing portion, respectively. ### Claim 11 (depends on 10) A device as claimed in claim 10, wherein the AC processing portion includes a unit for determining the RMS value of the signal and providing an AC component signal representative thereof. ### Claim 12 (depends on 10) A device as claimed in claim 10, wherein the AC processing portion includes a high pass filter. ### Claim 13 (depends on 12) A device as claimed in claim 12, wherein the AC processing portion includes a unit for determining the RMS value of the signal and providing an AC component signal representative thereof. ### Claim 14 (depends on 13) A device as claimed in claim 13, wherein the AC processing portion includes a ratio-determining unit that determines the ratio of a reference signal to the AC component signal and produces a ratio signal representative thereof. ### Claim 15 (depends on 14) A device as claimed in claim 14, wherein the reference signal is determined externally by a different AC current monitor. ### Claim 16 (depends on 1) A device as claimed in claim 1, wherein the signal processing unit separately processes AC signals and signals at or near DC with an AC processing portion and a DC processing portion, respectively; wherein the DC processing portion includes a unit for determining the mean of the signals and providing a DC component signal representative thereof; wherein the AC processing portion includes a unit for determining the RMS value of the signal and providing an AC component signal representative thereof; wherein the AC processing portion includes a ratio-determining unit that determines the ratio of a reference signal to the AC component signal and produces a ratio signal representative thereof; and wherein the signal processing unit includes a multiplier unit that multiplies the DC component signal by the ratio signal. ### Claim 17 (depends on 1) A device as claimed in claim 1, wherein the signal processing unit determines a DC component and an AC component; and wherein the AC component is compared to a reference signal representative of an external measurement of the AC current in the power transmission line and, based on the comparison, the DC component is adjusted in proportion thereto. ### Claim 18 (depends on 1) A device as defined in claim 1, wherein the device includes a transmitter and an antenna for communicating geomagnetically-induced current information to an external device. ### Claim 19 (depends on 18) A device as defined in claim 18, wherein the external device includes a receiver for receiving information related to geomagnetically-induced currents. ### Claim 20 (depends on 1) A device as defined in claim 1, wherein the device includes a current transformer for drawing current off of the power transmission line to provide operating power to the device. ### Claim 21 (depends on 1) A device as defined in claim 1, wherein the magnetic sensor includes a Hall effect sensor. ### Claim 22 (depends on 21) A device as defined in claim 21, wherein the output signal from the sensor is an analog signal and the device includes an analog-to-digital (A/D) converter. ### Claim 23 (depends on 22) A device as defined in claim 22, wherein the analog signal is provided from the sensor to the A/D converter via a twisted pair of wires. ### Claim 24 (depends on 1) A device as defined in claim 1, wherein the injecting unit includes a coil placed relative to the power transmission line in order to inject the reactance therein. ### Claim 25 (depends on 1) A device as claimed in claim 1, wherein the magnetic sensor is electrically connected only to the signal processing unit. ### Claim 26 (depends on 25) A device as claimed in claim 25, wherein the magnetic sensor is thus electrically isolated from ground. ### Claim 27 A device for monitoring geomagnetically-induced currents in a power transmission line, comprising: a magnetic core disposed about a power transmission line, the core being configured to provide an air gap therein, wherein with the exception of the air gap, the magnetic core completely surrounds the power transmission line; a magnetic sensor positioned in the air gap to sense magnetic fields and produce an output signal representative of the magnetic fields; and a signal processing unit that receives the output signal and determines the magnitude of a geomagnetically-induced current in the power transmission line therefrom; wherein the magnetic sensor is electrically connected only to the signal processing unit and thus electrically isolated from ground. ### Claim 28 (depends on 27) A device as claimed in claim 27, further including an upper housing and a lower housing that are configured for placement around the power transmission line and for attachment to each other to contain the core, sensor, and signal processing unit therein. ### Claim 29 (depends on 27) A device as claimed in claim 27, wherein the core includes at least two separate core portions. ### Claim 30 (depends on 27) A device as claimed in claim 27, wherein the core includes at least three separate core portions. ### Claim 31 (depends on 30) A device as claimed in claim 30, wherein one of the three separate core portions is configured to extend approximately 180 degrees around the power transmission line. ### Claim 32 (depends on 30) A device as claimed in claim 30, wherein two of the three separate core portions are each configured to extend only approximately 90 degrees around the power transmission line. ### Claim 33 (depends on 27) A device as claimed in claim 27, wherein the signal processing unit determines a DC component and an AC component; and wherein the AC component is compared to a reference signal representative of an external measurement of the AC current in the power transmission line and, based on the comparison, the DC component is adjusted in proportion thereto. ### Claim 34 (depends on 27) A device as defined in claim 27, wherein the device includes a current transformer for drawing current off of the power transmission line to provide operating power to the device.