# US 12,224,576 B2 · Protection circuitry for a downhole measurement tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,576 B2 - Document ID: US12224576B2 - Status: Granted - Kind: B2 - Application number: 18/180,641 - Filed: 2023-03-08 - Published: 2024-09-12 - Granted: 2025-02-11 - Earliest claimed: 2023-03-08 - Assignees: ChampionX LLC - Applicants: ChampionX LLC - Inventors: Robert J. Schapper - Web page: https://patentgrep.com/patent/US12224576B2 ## CPC - H02H 7/08: for dynamo-electric motors - E21B 17/028: {Electrical or electro-magnetic connections} - E21B 43/128: {Adaptation of pump systems with down-hole electric drives} - E21B 47/017: Protecting measuring instruments - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Systems and methods corresponding to a downhole measurement tool to balance fault current in a protective inductor are disclosed herein. A triggerable network is provided which keeps an alternating current balanced in a protective choke during a phase-to-ground fault condition in a power cable or a downhole motor of an electrical submersible pump. The triggerable network causes a conducting of current during negative polarity voltage portion(s) of the phase-to-ground fault condition via a silicon-controlled rectifier having an anode and a cathode on a path of current conduction for the negative polarity voltage during the phase-to-ground fault condition and one or more Zener diodes, where an ending cathode of the one or more Zener diodes is coupled to a gate of the silicon-controlled rectifier and an ending anode of the one or more Zener diodes is coupled to the anode of the silicon-controlled rectifier. ## Claims ### Claim 1 A downhole system capable of balancing an alternating current between a power cable or a downhole motor of an electrical submersible pump and a downhole measurement tool during a phase-to-ground fault condition, the downhole system comprising: an electrical connection between a Y-point of the downhole motor of the electrical submersible pump and the downhole measurement tool; and a triggerable network that selectively conducts during an application of a negative polarity voltage to the downhole measurement tool during the phase-to-ground fault condition, the triggerable network comprising: a silicon-controlled rectifier having an anode and a cathode on a first path of current conduction for the negative polarity voltage during the phase-to-ground fault condition; and one or more first Zener diodes, wherein an ending anode of the one or more first Zener diodes is coupled to a gate of the silicon-controlled rectifier and an ending cathode of the first one or more Zener diodes is coupled to the anode of the silicon-controlled rectifier. ### Claim 2 (depends on 1) The downhole system capable of claim 1, wherein the one or more first Zener diodes comprises a plurality of Zener diodes coupled in series. ### Claim 3 (depends on 1) The downhole system capable of claim 1, wherein a trigger current for the silicon-controlled rectifier at the gate of the silicon-controlled rectifier occurs through the one or more first Zener diodes during the application of the negative polarity voltage. ### Claim 4 (depends on 3) The downhole system capable of claim 3, wherein the trigger current occurs based on a magnitude of the negative polarity voltage. ### Claim 5 (depends on 1) The downhole system capable of claim 1, further comprising a diode providing a second path of current conduction for a positive polarity voltage during the phase-to-ground fault condition and one or more second Zener diodes configured to limit a magnitude of the positive polarity voltage. ### Claim 6 (depends on 5) The downhole system capable of claim 5, wherein the one or more second Zener diodes comprises a plurality of Zener diodes coupled in series. ### Claim 7 (depends on 1) The downhole system capable of claim 1, further comprising an inductor coupled to the Y-point of the downhole motor of the electrical submersible pump and the downhole measurement tool, the inductor being of a selected inductance for filtering alternating current ripple voltage from the downhole motor of the electrical submersible pump to the downhole measurement tool, wherein: the anode of the silicon-controlled rectifier is coupled to a ground; and the cathode of the silicon-controlled rectifier is coupled to the inductor. ### Claim 8 (depends on 1) The downhole system capable of claim 1, wherein the triggerable network further comprises a blocking diode, and wherein the ending anode of the one or more first Zener diodes and the gate of the silicon-controlled rectifier are coupled through the blocking diode. ### Claim 9 A downhole measurement tool having circuitry capable of balancing an alternating current during a phase-to-ground fault condition, the downhole measurement tool capable of being coupled to a Y-point of a three-phase downhole motor of an electrical submersible pump, the circuitry of the downhole measurement tool comprising: a triggerable network that selectively conducts during an application of a negative polarity voltage to the downhole measurement tool, the triggerable network comprising: a silicon-controlled rectifier having an anode and a cathode on a first path of current conduction for the negative polarity voltage during the phase-to-ground fault condition; and one or more first Zener diodes, wherein an ending anode of the one or more first Zener diodes is coupled to a gate of the silicon-controlled rectifier and an ending cathode of the first one or more Zener diodes is coupled to the anode of the silicon-controlled rectifier; and an inductor commutating circuit to limit a magnitude of a positive polarity voltage during the phase to-ground fault condition. ### Claim 10 (depends on 9) The downhole measurement tool of claim 9, wherein the one or more first Zener diodes comprises a plurality of Zener diodes coupled in series. ### Claim 11 (depends on 9) The downhole measurement tool of claim 9, wherein a trigger current for the silicon-controlled rectifier at the gate of the silicon-controlled rectifier occurs through the one or more first Zener diodes during the application of the negative polarity voltage. ### Claim 12 (depends on 11) The downhole measurement tool of claim 11, wherein the trigger current occurs based on a magnitude of the negative polarity voltage. ### Claim 13 (depends on 9) The downhole measurement tool of claim 9, wherein the inductor commutating circuit comprises a diode providing a second path of current conduction for the positive polarity voltage during the phase-to-ground fault condition and one or more second Zener diodes. ### Claim 14 (depends on 13) The downhole measurement tool of claim 13, wherein the one or more second Zener diodes comprises a plurality of Zener diodes coupled in series. ### Claim 15 (depends on 9) The downhole measurement tool of claim 9, further comprising an inductor coupled to the Y-point of the downhole motor of the electrical submersible pump and the downhole measurement tool, the inductor being of a selected inductance for filtering alternating current ripple voltage from the downhole motor of the electrical submersible pump to the downhole measurement tool, wherein: the anode of the silicon-controlled rectifier is coupled to a ground; and the cathode of the silicon-controlled rectifier is coupled to the inductor. ### Claim 16 (depends on 9) The downhole measurement tool of claim 9, wherein the triggerable network further comprises a blocking diode, and wherein the ending anode of the one or more first Zener diodes and the gate of the silicon-controlled rectifier are coupled through the blocking diode. ### Claim 17 A method of balancing a phase-to-ground fault condition between a power cable or a three-phase downhole motor of an electrical submersible pump and a downhole measurement tool, the method comprising: coupling a Y-point of the downhole motor of the electrical submersible pump to the downhole measurement tool; selectively conducting through a triggerable network during an application of a negative polarity voltage to the downhole measurement tool during the phase-to ground fault condition, wherein the triggerable network comprises: a silicon-controlled rectifier having an anode and a cathode on a first path of current conduction for the negative polarity voltage during the phase-to-ground fault condition; and one or more first Zener diodes, wherein an ending anode of the one or more first Zener diodes is coupled to a gate of the silicon-controlled rectifier and an ending cathode of the first one or more Zener diodes is coupled to the anode of the silicon-controlled rectifier; and providing a second path of current conduction for a positive polarity voltage during the phase-to-ground fault condition. ### Claim 18 (depends on 17) The method of claim 17, wherein the one or more first Zener diodes comprises a plurality of Zener diodes coupled in series. ### Claim 19 (depends on 17) The method of claim 17, wherein a trigger current for the silicon-controlled rectifier at the gate of the silicon-controlled rectifier occurs through the one or more first Zener diodes during the application of the negative polarity voltage. ### Claim 20 (depends on 19) The method of claim 19, wherein the trigger current occurs based on a magnitude of the negative polarity voltage. ### Claim 21 (depends on 17) The method of claim 17, wherein the second path of current conduction for the positive polarity voltage comprises a diode and one or more second Zener diodes configured to limit a magnitude of the positive polarity voltage. ### Claim 22 (depends on 21) The method of claim 21, wherein the one or more second Zener diodes comprises a plurality of Zener diodes coupled in series. ### Claim 23 (depends on 21) The method of claim 21, wherein: the Y-point of the downhole motor of the electrical submersible pump is coupled to the downhole measurement tool through an inductor of a selected inductance for filtering alternating current ripple voltage from the downhole motor of the electrical submersible pump to the downhole measurement tool; the anode of the silicon-controlled rectifier is coupled to a ground; and the cathode of the silicon-controlled rectifier is coupled to the inductor. ### Claim 24 (depends on 21) The method of claim 21, wherein the triggerable network further comprises a blocking diode, and wherein the ending anode of the one or more first Zener diodes and the gate of the silicon-controlled rectifier are coupled through the blocking diode.