DESC:Field of the Invention
The present invention relates generally to grounding resistance measurement and monitoring systems for energized electrical installations, and more particularly to a controlled DC excitation-based earth resistance measurement system employing stabilized sampling techniques for monitoring grounding integrity.
Background of the Invention

Grounding systems serve as a critical safety mechanism in electrical power distribution infrastructure. In transformer installations and other energized electrical equipment, proper grounding enables dissipation of fault currents, protection against lightning surges, reliable operation of protective relays, reduction of hazardous touch and step voltages, and prevention of equipment insulation breakdown. The integrity of grounding systems therefore directly affects operational safety, equipment reliability, and continuity of electrical service.
Utilities and infrastructure operators conventionally assess earth resistance of transformer grounding systems using portable earth resistance testing equipment. Such measurements are typically performed manually at scheduled intervals, for example once every several months. However, grounding conditions may vary significantly between measurement intervals due to corrosion of grounding electrodes, loosening of grounding connections, conductor breakage, theft of earthing conductors, soil drying, moisture variation, and seasonal environmental changes. Consequently, periodic testing may fail to detect progressive or sudden grounding degradation in a timely manner.
Many conventional earth resistance measurement techniques employ alternating current (AC)-based excitation methods, including fall-of-potential testing arrangements and clamp-based measurement systems. AC-based approaches may be preferred in conventional systems because alternating excitation reduces persistent electrochemical charge accumulation at the electrode-soil interface and supports transformer-based inductive measurement techniques. However, in practical grounding environments, surrounding soil and grounding structures may exhibit capacitive and inductive characteristics, causing AC-based measurements to include reactive impedance components in addition to the resistive grounding component. As a result, measured values may reflect composite impedance behavior rather than accurately representing grounding resistance.
Further, AC-based measurements may be adversely affected by electromagnetic interference, stray currents, harmonics, switching transients, and ambient electrical noise commonly present in energized transformer environments. Clamp-based AC measurement arrangements may additionally estimate loop impedance rather than directly characterizing the resistive condition of a grounding path. Such factors may reduce measurement stability and reliability, particularly in continuously energized field installations.
Although direct current (DC)-based measurement approaches may theoretically reduce reactive impedance effects associated with AC excitation, simple DC excitation presents its own technical limitations. When DC current is continuously or repeatedly applied between grounding electrodes in conductive soil environments, electrochemical phenomena may arise at the electrode-soil interface, including charge accumulation, ionic polarization, electrode polarization, and electrolysis-related effects. These phenomena may introduce time-dependent drift in measured voltage and current values even when the physical grounding condition remains unchanged.
In addition, prolonged unidirectional DC excitation may contribute to localized electrode degradation, accelerated corrosion, material deposition, or alteration of interface conductivity, thereby adversely affecting measurement repeatability and potentially influencing the long-term condition of measurement electrodes or connected grounding structures. Accordingly, simplistic DC injection techniques may not reliably provide stable and repeatable grounding resistance estimation in energized operational environments.
Environmental factors such as temperature variation, humidity, soil moisture content, soil composition, and seasonal conditions may further influence measured grounding resistance values. Variations attributable to environmental conditions may be difficult to distinguish from actual grounding degradation, thereby increasing the likelihood of inaccurate interpretation or false abnormality detection.
Conventional approaches also generally lack continuous or near real-time monitoring capability. Without persistent visibility into grounding system health, operators may be unable to identify developing grounding faults before such conditions result in unsafe voltage conditions, transformer damage, equipment failure, or service interruption. Further, absence of historical measurement data may limit predictive maintenance planning and asset health analysis.
Accordingly, there exists a need for improved grounding resistance measurement systems and methods capable of providing stable and reliable determination of grounding integrity in energized electrical installations while reducing limitations associated with conventional AC-based measurement techniques and simplistic DC excitation approaches.

Objective of the Invention

The principal objective of the present invention is to provide an improved grounding resistance measurement and monitoring system for energized electrical installations, capable of enabling effective evaluation of grounding integrity under operational conditions.
Another objective of the present invention is to provide a solution for reliable assessment of grounding integrity associated with power distribution equipment, particularly in installations where grounding performance directly influences operational safety and equipment protection.
Another objective of the present invention is to overcome drawbacks and technical limitations associated with conventional grounding measurement approaches, including AC-based measurement techniques and simplistic DC-based excitation methods.
Another objective of the present invention is to facilitate continuous or periodic monitoring of grounding system health without reliance on repeated manual inspection or conventional field-based testing procedures.
Another objective of the present invention is to enable timely identification of grounding degradation, abnormal grounding conditions, or progressive deterioration, thereby supporting predictive maintenance and improved asset management of electrical infrastructure.
A further objective of the present invention is to enhance operational safety, improve equipment reliability, and promote continuity of electrical service through effective monitoring and evaluation of grounding system condition.

Summary of the Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
The present invention addresses technical limitations associated with conventional grounding resistance measurement techniques used for monitoring grounding integrity of energized electrical installations. Existing AC-based grounding measurement approaches are affected by reactive impedance contributions arising from inductive and capacitive characteristics of the grounding environment, resulting in measurements that do not accurately represent the true resistive component of the grounding path. Known DC-based measurement approaches may also suffer from instability caused by transient response behavior, electrode polarization effects, electrochemical interface behavior, and time-dependent measurement drift, thereby reducing reliability and repeatability of grounding resistance determination.
Further, environmental factors including temperature, humidity, soil moisture, and related site conditions may significantly influence grounding resistance behavior, making it difficult to distinguish between resistance variation caused by environmental fluctuations and resistance variation caused by actual grounding degradation. Conventional manual testing approaches also fail to provide continuous visibility into grounding condition, thereby delaying detection of abnormal grounding conditions and limiting predictive maintenance capability.
To address the foregoing technical problems, the present invention provides a grounding resistance measurement and monitoring system configured to determine grounding resistance of an energized electrical installation using controlled direct current excitation applied between grounding nodes associated with the installation. The system employs polarity-controlled excitation in which the applied excitation may be selectively reversed between a first grounding node and a second grounding node to enable bidirectional grounding response evaluation.
The system includes sensing circuitry configured to measure one or more electrical parameters associated with the applied excitation signal and a processing unit configured to determine a grounding resistance value based on the measured electrical parameters. In certain implementations, the processing unit is configured to determine the grounding resistance value after identifying a substantially stable measurement condition following excitation application, thereby reducing the influence of transient response behavior and improving reliability of resistance determination. The grounding resistance may be determined based on voltage and current measurements associated with the applied excitation signal.
In certain aspects, excitation may be applied in controlled time intervals separated by non-measurement intervals to reduce transient interference between successive excitation operations. Grounding resistance determination may be based on measurements obtained during excitation in forward and reversed polarity conditions, thereby reducing directional bias, minimizing interface-dependent measurement effects, and improving consistency of grounding resistance evaluation.
The system may further include one or more environmental sensing modules configured to detect environmental conditions associated with the energized electrical installation, wherein the determined grounding resistance value may be compensated or normalized based on detected environmental conditions to improve interpretation of grounding behavior.
The system may further include abnormality detection functionality configured to identify grounding degradation based on threshold comparison, trend analysis, baseline comparison, or rate-of-change analysis of determined grounding resistance values. Abnormal conditions including corrosion, grounding conductor degradation, grounding disconnection, earthing strip failure, loose grounding connections, surge-induced damage, theft of grounding conductors, or related grounding integrity faults may thereby be detected.
The system may further include communication functionality for transmitting grounding condition data, diagnostic information, alert information, or abnormality data to a remote monitoring platform, including supervisory monitoring infrastructure, cloud-based monitoring platforms, utility monitoring systems, or equivalent remote monitoring arrangements. Measurement records may also be stored locally for historical analysis, diagnostic review, and predictive maintenance applications.
The present invention also provides a method for monitoring grounding integrity of an energized electrical installation, the method including applying a controlled DC excitation signal between grounding nodes associated with the installation, selectively reversing polarity of the excitation signal, measuring one or more electrical parameters associated with the applied excitation, determining whether the measured electrical parameters satisfy a substantially stable measurement condition, determining a grounding resistance value based on the measured electrical parameters, and evaluating grounding integrity based on the determined grounding resistance value.
Accordingly, the present invention provides an improved grounding resistance measurement and monitoring solution capable of enabling reliable grounding resistance determination, continuous or interval-based grounding condition monitoring, abnormality detection, and predictive maintenance support for energized electrical installations.
The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this invention and are not restrictive.

Brief description of the drawings

The figures described below depict various aspects of the system and methods disclosed herein. It should be understood that each figure depicts an embodiment of a particular aspect of the disclosed system and methods, and that each of the figures is intended to accord with a possible embodiment thereof. Further, wherever possible, the following description refers to the reference numerals included in the following figures, in which features depicted in multiple figures are designated with consistent reference numerals.
FIG.1 illustrates an overall grounding resistance measurement and monitoring system architecture (100) for monitoring grounding integrity of an energized electrical installation, according to one embodiment of the present invention.
FIG.2 illustrates a bidirectional DC excitation and polarity reversal architecture for grounding resistance measurement between grounding nodes associated with the energized electrical installation (200), according to another embodiment of the present invention.
FIG.3 illustrates a measurement timing and stabilized sampling sequence (300) for controlled bidirectional grounding resistance determination and post-processing evaluation, according to another embodiment of the present invention.
FIG.4 illustrates a method for monitoring grounding integrity (400) of an energized electrical installation, according to another embodiment of the present invention.
Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present invention.
Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

Detailed Description of the Invention

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.
By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic is intended to provide.
Figures discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions, in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element.
The present invention provides a grounding resistance measurement and monitoring system configured for monitoring grounding integrity of an energized electrical installation.
The system may determine grounding resistance based on measured voltage and current associated with a controlled DC excitation signal applied between grounding nodes of the energized electrical installation.
The system includes a controlled DC excitation module configured to apply an excitation signal between a first grounding node and a second grounding node associated with an energized electrical installation. The controlled DC excitation module may include a regulated direct current excitation source configured to generate a controlled electrical stimulus for evaluation of a grounding path associated with the energized electrical installation.
The first grounding node may correspond to a transformer earth connection, equipment grounding point, grounding conductor connection, grounding electrode interface, or another grounding connection associated with the energized electrical installation. The second grounding node may correspond to a neutral earth connection, ground reference point, secondary grounding electrode, or another grounded reference connection.
The system further includes a polarity reversal module configured to selectively reverse polarity of the excitation signal between the first grounding node and the second grounding node. The polarity reversal module may include relay switching circuitry, semiconductor switching arrangements, bidirectional switching logic, H-bridge circuitry, or equivalent polarity control arrangements configured to reverse the direction of current flow through the grounding path.
The system further includes a sensing module configured to measure one or more electrical parameters associated with the applied excitation signal. The one or more electrical parameters may include voltage response, current response, voltage drop across the grounding path, excitation current magnitude, derived resistance-related parameters, or equivalent measurable electrical characteristics associated with the grounding system.
The system further includes a processing unit operatively coupled to the sensing module and configured to determine a grounding resistance value based on the measured electrical parameters. The processing unit may include a microcontroller, processor, embedded computing circuitry, programmable logic, digital signal processing circuitry, or equivalent computational architecture configured to process acquired measurement data.
The processing unit is further configured to evaluate grounding integrity based on the determined grounding resistance value. Grounding integrity evaluation may include threshold comparison, baseline comparison, trend analysis, abnormality detection, rate-of-change evaluation, or diagnostic assessment for identifying degradation of the grounding system.
In certain implementations, the grounding resistance measurement and monitoring system may further include protection circuitry, stabilization determination functionality, environmental compensation functionality, abnormality detection functionality, communication functionality, data storage functionality, and remote monitoring capability.
Figure 1 illustrates an overall grounding resistance measurement and monitoring system architecture (100) for monitoring grounding integrity of an energized electrical installation, according to the present invention.
The grounding resistance measurement and monitoring system (100) is configured for deployment in association with an electrical installation (105) such as a power distribution transformer, ring main unit, substation equipment, industrial electrical equipment, or other grounded electrical infrastructure where continuous or interval-based monitoring of grounding condition is required. The system enables grounding assessment while the electrical installation (105) remains energized and operational, thereby allowing measurement under actual operating conditions without dependence on shutdown-based testing procedures.
As illustrated, the electrical installation (105) includes a first grounding node (110) and a second grounding node (120). The first grounding node (110) may correspond to a transformer earth connection, equipment body grounding point, grounding conductor connection, or associated grounding electrode connection. The second grounding node (120) may correspond to a neutral earth connection, reference grounding point, neutral grounding conductor, or another electrically grounded reference node. A conductive grounding path exists between the first grounding node (110) and the second grounding node (120) through surrounding soil, grounding conductors, grounding electrodes, connectors, and associated grounding infrastructure.
The grounding resistance measurement and monitoring system (100) includes a protection/isolation module (115) electrically coupled to the energized electrical installation (105). The protection/isolation module (115) protects measurement circuitry from disturbances present in energized electrical environments. Such disturbances may include surge currents, overvoltage conditions, lightning-induced transients, switching disturbances, fault-induced electrical stress, or abnormal voltage conditions. The protection/isolation module (115) may include galvanic isolation circuitry, surge suppression devices, transient protection devices, overvoltage limiting circuitry, current limiting arrangements, fault isolation components, or combinations thereof.
The output of the protection/isolation module (115) is coupled to a controlled DC excitation module (125). The controlled DC excitation module (125) is configured to generate a controlled excitation signal for grounding resistance measurement. The excitation source may be implemented as a programmable DC voltage source, regulated DC current source, pulse-controlled excitation circuit, programmable excitation generator, or equivalent controlled excitation arrangement. The controlled DC excitation may be applied continuously, periodically, or within defined measurement intervals depending on measurement requirements.
The controlled DC excitation module (125) is operatively coupled to a polarity reversal module (130). The polarity reversal module (130) is configured to selectively reverse the polarity of the excitation signal applied between the first grounding node (110) and the second grounding node (120). The polarity reversal module (130) may be implemented using relay switching arrangements, semiconductor switching networks, bidirectional switching circuitry, H-bridge switching architecture, solid-state switching elements, or equivalent polarity control arrangements. The polarity reversal functionality allows excitation current to be driven through the grounding path in opposite directions during separate measurement operations.
During operation, the controlled DC excitation module (125) generates a controlled excitation signal, and the polarity reversal module (130) selectively applies the excitation signal between the first grounding node (110) and the second grounding node (120) in a forward polarity condition or a reversed polarity condition, thereby causing current flow through the grounding path. Since the measurement employs controlled direct current excitation, reactive impedance effects commonly associated with AC-based measurement methods are substantially avoided, thereby enabling determination of the resistive component of the grounding path.
In a first measurement cycle, the polarity reversal module (130) may apply the excitation signal in a forward polarity condition such that current flows from the first grounding node (110) toward the second grounding node (120). In a subsequent measurement cycle, the polarity reversal module (130) may reverse the excitation polarity such that current flows from the second grounding node (120) toward the first grounding node (110). Measurements obtained under both polarity conditions may be processed for determination and validation of grounding resistance.
A voltage/current sensing module (135) is provided downstream of the polarity reversal module (130). The voltage/current sensing module (135) is configured to measure one or more electrical parameters associated with the applied excitation signal. A voltage sensing portion detects voltage response associated with the grounding path, while a current sensing portion detects current response resulting from the applied excitation. The sensing module (135) may include shunt-based sensing circuits, current sensing resistors, Hall-effect sensors, instrumentation amplifiers, isolated sensing arrangements, differential sensing circuitry, or equivalent measurement components.
Measured electrical parameters from the voltage/current sensing module (135) are supplied to a signal acquisition module (140), which may include analog-to-digital conversion circuitry. The signal acquisition module (140) acquires analog measurement signals and converts the signals into digital measurement data for subsequent processing. Signal conditioning circuitry may also be associated with the signal acquisition module (140) for amplification, scaling, filtering, offset correction, or noise reduction.
Digital measurement data acquired through the signal acquisition module (140) is supplied to a processing unit/controller (145), which performs measurement analysis and grounding condition evaluation. The processing unit/controller (145) may comprise a microcontroller, embedded processor, digital signal processor, programmable controller, computing module, or equivalent control circuitry.
The processing unit/controller (145) includes a stabilization determination module (150) configured to identify a suitable measurement condition for reliable grounding resistance determination. Immediately following excitation application, switching transitions, or polarity reversal, transient electrical behavior may occur due to charging effects, switching disturbances, soil interface response, electrode polarization effects, electrochemical stabilization effects, or other transient phenomena. The stabilization determination module (150) rejects unstable measurement conditions and determines when the measurement response reaches a substantially stable condition suitable for resistance evaluation. Stability may be identified using elapsed timing criteria, voltage stabilization behavior, current stabilization behavior, derivative analysis, resistance convergence monitoring, rate-of-change evaluation, or equivalent stabilization assessment techniques.
The processing unit/controller (145) further includes a ground resistance determination module (155) configured to determine grounding resistance using acquired electrical measurements. Grounding resistance may be determined using measured voltage and current values according to resistance determination principles such as voltage-to-current ratio evaluation. In one implementation, grounding resistance may be determined according to Ohm's Law:
R = V / I
where R represents grounding resistance, V represents measured voltage associated with the grounding path, and I represents measured excitation current through the grounding path.
Accordingly, by measuring the voltage response and current response associated with the controlled DC excitation, the ground resistance determination module (155) determines the effective grounding resistance corresponding to the conductive grounding path between the grounding nodes.
Where bidirectional excitation is employed, the ground resistance determination module (155) may process measurements obtained during forward and reverse excitation cycles. Measurements obtained under both polarity conditions may be combined, validated, compared, averaged, or subjected to consistency evaluation to improve measurement reliability, reduce directional bias effects, compensate for grounding interface asymmetries, and support more accurate grounding resistance determination.
An environmental sensing module (160) is associated with the processing unit/controller (145) for detecting environmental conditions that may influence grounding behavior. Environmental parameters detected by the environmental sensing module (160) may include temperature, humidity, soil moisture, rainfall conditions, seasonal variations, ambient environmental conditions, or related environmental variables affecting soil conductivity and grounding resistance.
An environmental compensation module (165) is associated with the processing unit/controller (145) for compensating or normalizing resistance measurements based on environmental conditions detected by the environmental sensing module (160). Variations in soil moisture, temperature, humidity, and related environmental factors may influence grounding resistance measurements even in the absence of structural degradation in the grounding system. The environmental compensation module (165) reduces environmentally induced variability to improve interpretation of actual grounding health.
The processing unit/controller (145) further includes an abnormality detection module (170) configured to evaluate grounding condition based on measured resistance behavior. The abnormality detection module (170) may perform threshold comparison, trend analysis, baseline comparison, rate-of-change analysis, anomaly detection, or related diagnostic evaluation.
In some implementations, the abnormality detection module (170) may identify degradation of the grounding system based on changes in measured grounding resistance over time. For example, where a grounding resistance value previously measured at approximately 1.5 ohms subsequently increases to approximately 12 ohms, the abnormality detection module (170) may determine that a significant deterioration event has occurred within the grounding path. Such resistance increase may indicate progressive degradation of grounding performance and may trigger generation of maintenance alerts, inspection requests, or fault notifications.
In certain implementations, abnormality determination may be performed relative to a baseline grounding resistance value established during installation, commissioning, or a previous healthy operating condition. An alert condition may be generated when the determined grounding resistance exceeds a predefined threshold, exceeds the baseline value by a predetermined percentage, or exhibits a rate of increase exceeding a predefined trend criterion.
Detected abnormal conditions may include corrosion of grounding electrodes, corrosion of earthing strips, degradation of grounding conductors, breakage of earthing strips, disconnection of grounding conductors, theft of grounding conductors, surge-induced grounding damage, open-circuit conditions, loose grounding connections, reduction in soil conductivity due to dry soil conditions, or other grounding-related faults.
For example, a gradual increase in grounding resistance over an extended period may be associated with corrosion of grounding electrodes, corrosion of earthing strips, or degradation of grounding conductors. A sudden increase in grounding resistance may indicate breakage of an earthing strip, disconnection of a grounding conductor, theft of a grounding conductor, or loosening of a grounding connection. An increase in grounding resistance correlated with environmental measurements may indicate reduced soil conductivity resulting from dry soil conditions. In certain cases, grounding resistance may increase following lightning events, surge events, or fault-current discharge events, thereby indicating possible grounding system damage requiring inspection.
A communication module (175) is coupled to the processing unit/controller (145) for transmission of measurement information, diagnostic information, grounding condition data, abnormality information, or alert notifications to external systems. The communication module (175) may support serial communication, Ethernet communication, cellular communication, radio-frequency communication, wireless telemetry, low-power wide-area communication, industrial communication protocols, supervisory monitoring interfaces, or equivalent wired or wireless communication mechanisms.
The communication module (175) communicates with a remote monitoring platform (180), which may comprise a supervisory control and data acquisition (SCADA) platform, cloud-based monitoring infrastructure, utility monitoring center, transformer monitoring platform, or equivalent remote monitoring system.
The remote monitoring platform (180) may provide real-time visibility into grounding condition, alarm and notification handling, historical trend analysis, predictive maintenance support, report generation, centralized asset monitoring, and system analytics.
In certain implementations, when an abnormal grounding condition is identified, the system may generate maintenance recommendations based on the detected degradation pattern. The maintenance recommendations may include inspection of grounding electrodes, verification of earthing strip continuity, confirmation of grounding conductor integrity, tightening of grounding connections, replacement of damaged grounding components, or soil condition assessment.
Measurement data, diagnostic results, alert events, timestamped historical records, and configuration information may also be stored locally in memory associated with the grounding resistance measurement and monitoring system (100) and synchronized with remote infrastructure when communication connectivity is available.
Accordingly, FIG. 1 illustrates an integrated system architecture through which grounding resistance of an energized electrical installation (105) is measured, processed, evaluated, and monitored using controlled DC excitation, polarity-controlled measurement operation, stabilized measurement processing, environmental compensation, abnormality detection, and remote monitoring functionality.
Figure 2 illustrates a bidirectional DC excitation architecture (200) employed in the grounding resistance measurement and monitoring system for selectively applying controlled DC excitation in opposite polarity directions between grounding nodes, thereby enabling grounding resistance determination based on measurements obtained under forward and reverse excitation conditions.
As illustrated in the upper portion of FIG. 2, the bidirectional DC excitation architecture (200) includes a first grounding node (205) and a second grounding node (210) associated with an energized electrical installation. The first grounding node (205) corresponds to a grounding connection associated with the monitored electrical installation, while the second grounding node (210) corresponds to a grounded reference connection. A conductive grounding path exists between the first grounding node (205) and the second grounding node (210) through grounding conductors, electrode interfaces, soil conduction paths, connectors, and associated grounding infrastructure.
The first grounding node (205) and the second grounding node (210) are electrically coupled to a protection/isolation module (215). The protection/isolation module (215) protects the measurement architecture from disturbances associated with energized installations, including surge voltages, transient electrical events, lightning-induced disturbances, overvoltage conditions, fault currents, switching transients, and related abnormal electrical conditions.
The protection/isolation module (215) may include one or more surge suppression devices, transient voltage protection devices, current limiting circuitry, galvanic isolation circuitry, fault interruption arrangements, overvoltage protection elements, or equivalent protective circuitry configured to protect measurement electronics during operation in energized electrical environments.
The output of the protection/isolation module (215) is coupled to a controlled DC excitation module (220). The controlled DC excitation module (220) is configured to generate a controlled direct current excitation signal for grounding resistance measurement. The excitation signal serves as a controlled electrical stimulus applied across the grounding path for resistance evaluation. The controlled DC excitation module (220) may be implemented as a regulated DC voltage source, regulated DC current source, programmable excitation source, pulse-controlled excitation circuit, or equivalent controlled excitation arrangement.
The controlled DC excitation module (220) is operatively coupled to a polarity reversal module (225). The polarity reversal module (225) is configured to selectively reverse the effective polarity of the excitation signal applied between the first grounding node (205) and the second grounding node (210). The polarity reversal module (225) may be implemented using relay switching arrangements, semiconductor switching circuitry, bidirectional switching logic, H-bridge switching networks, solid-state switching devices, or equivalent polarity control arrangements capable of reversing excitation direction through the grounding path.
Electrical response resulting from the applied excitation is measured by a voltage/current sensing module (230). The voltage/current sensing module (230) detects electrical parameters associated with the grounding response, including voltage response and current flow resulting from excitation through the grounding path.
Measured electrical response from the voltage/current sensing module (230) is supplied to a signal acquisition module (235), which may include analog-to-digital conversion circuitry for acquiring analog measurement signals and converting the signals into digital measurement data suitable for computational analysis.
Digital measurement data is then supplied to a processing unit/controller (240) configured to perform resistance determination, signal validation, response analysis, and grounding condition assessment.
The lower portion of FIG. 2 illustrates bidirectional excitation operation performed using the polarity reversal architecture.
During forward excitation mode (245), the controlled DC excitation is applied with a first polarity orientation between the grounding nodes. As illustrated, the forward excitation arrangement includes a first grounding node (250) corresponding to transformer earth and a second grounding node (255) corresponding to neutral earth or ground reference.
In this operational state, a DC excitation source (260) applies excitation such that the first grounding node (250) is associated with positive excitation polarity and the second grounding node (255) is associated with negative excitation polarity. As represented by the directional current indication (265), excitation current flows from the first grounding node (250) toward the second grounding node (255) through the grounding path.
Electrical response generated during forward excitation is measured through the sensing and acquisition architecture for subsequent processing.
During reverse excitation mode (270), the polarity reversal module (225) changes the effective polarity of the controlled DC excitation.
As illustrated, the reverse excitation arrangement includes a first grounding node (275) corresponding to transformer earth and a second grounding node (280) corresponding to neutral earth or ground reference.
In this operational state, the DC excitation source (285) applies reversed polarity excitation such that the second grounding node (280) is associated with positive excitation polarity while the first grounding node (275) is associated with negative excitation polarity. As represented by the directional current indication (290), excitation current flows from the second grounding node (280) toward the first grounding node (275) through the grounding path.
Electrical response generated during reverse excitation is similarly measured for subsequent analysis.
The bidirectional excitation architecture (200) enables grounding response evaluation under both current flow directions rather than relying solely on a single unidirectional excitation condition.
This bidirectional measurement approach is advantageous because practical grounding systems may exhibit directional asymmetry arising from electrode interface behavior, contact resistance variation, soil conduction non-uniformity, localized degradation, connector conditions, electrochemical interface effects, or installation-specific grounding characteristics. A resistance determination based solely on a single excitation direction may therefore be influenced by directional bias or localized interface effects.
By acquiring measurements under both forward excitation mode (245) and reverse excitation mode (270), the processing unit/controller (240) may perform comparative evaluation, consistency validation, averaging, directional bias reduction, or equivalent bidirectional resistance determination processing.
Bidirectional excitation also assists in reducing distortion associated with interface-dependent electrochemical behavior that may otherwise influence single-direction DC measurements. Reversing excitation direction reduces the likelihood that persistent directional electrochemical effects dominate the measured response.
Repeated excitation in a single polarity direction may promote accumulation of electrochemical charge at electrode-soil interfaces, thereby introducing polarization-dependent measurement drift. Selective reversal of excitation polarity redistributes accumulated interface charge and reduces persistent directional electrochemical imbalance, thereby improving repeatability and consistency of grounding resistance determination.
Accordingly, FIG. 2 illustrates the bidirectional excitation architecture (200) through which polarity-controlled DC excitation is selectively applied across the grounding path to enable forward and reverse measurement acquisition for grounding resistance determination.
Figure 3 illustrates a measurement timing and stabilized sampling architecture (300) employed by the grounding resistance measurement and monitoring system for obtaining reliable grounding resistance measurements under energized operating conditions. The figure particularly illustrates a controlled sequential measurement process involving bidirectional excitation, a defined non-measurement interval, post-processing operations, and continuous monitoring functions.
As illustrated, the measurement process receives grounding inputs (305) corresponding to grounding connections associated with the monitored electrical installation, including a first grounding node and a second grounding node through which grounding response is evaluated.
The measurement process is governed by a control and timing manager (310) configured to coordinate operational timing associated with excitation application, excitation interruption, polarity transition, measurement sequencing, and sequence repetition. The control and timing manager (310) may be implemented using firmware executed by a processing unit, programmable timing logic, embedded sequencing circuitry, control software, or equivalent timing management architecture.
The grounding inputs (305) are electrically associated with a protection / isolation module (315), which protects the measurement architecture from surge conditions, transient disturbances, overvoltage events, fault-induced electrical stress, and abnormal electrical conditions associated with energized installations.
The central portion of FIG. 3 illustrates a measurement sequence (320) representing one complete measurement cycle.
The measurement sequence (320) includes Phase 1 forward excitation (325), during which controlled DC excitation is applied in a forward polarity orientation between the grounding nodes. During this phase, excitation current flows through the grounding path in a first directional condition, thereby allowing electrical response associated with the grounding path to be evaluated.
Following initiation of forward excitation, the grounding response may initially exhibit transient electrical behavior arising from switching disturbances, electrode interface charging, soil conduction stabilization, charge redistribution, capacitive settling effects, electrochemical response, and other time-dependent effects. The measurement system therefore allows the response to progress toward a sufficiently stable condition suitable for reliable resistance evaluation.
During the transient interval, measured electrical parameters may vary with time due to capacitive charging effects, electrode-soil interface polarization, charge redistribution, and transient conduction behavior within the grounding medium. Accordingly, the processing unit may assess temporal variation of the measured electrical parameters to determine whether a substantially stable measurement condition has been achieved.
In one implementation, stabilization may be identified based on a rate-of-change condition in which the variation of measured resistance with respect to time approaches zero, represented as:
dR/dt ˜ 0
where R represents the determined grounding resistance value and t represents elapsed time during the measurement interval.
When the rate of change falls below a predefined threshold, the measurement condition may be treated as substantially stable for reliable grounding resistance determination.
In certain implementations, the measured grounding response may be modeled as a time-dependent resistance function represented as:
R(t) = Rtrue + Rtransient(t)
where Rtrue represents the actual resistive component of the grounding path and Rtransient(t) represents transient error contributions arising from switching response, capacitive effects, electrochemical interface behavior, or polarization effects.
As time progresses and transient contributions diminish, the measured response approaches the true grounding resistance value, thereby improving measurement reliability.
The measurement sequence (320) further includes an interval / dead time (330) during which excitation is intentionally interrupted.
The interval / dead time (330) serves as a controlled excitation-off period between directional excitation phases. Interruption of excitation allows residual transient effects associated with the preceding excitation phase to decay before initiation of the subsequent measurement phase. The interval / dead time (330) also reduces overlap between forward excitation behavior and reverse excitation behavior, thereby minimizing transitional measurement contamination. Additionally, interruption of excitation assists in reducing persistent electrochemical interface effects that may otherwise continue influencing subsequent measurements if polarity reversal occurs immediately without temporal separation.
Following completion of the interval / dead time (330), the measurement sequence enters Phase 2 reverse excitation (335), during which the controlled DC excitation is applied in reverse polarity orientation.
During reverse excitation (335), current flows through the grounding path in a direction opposite to that of forward excitation. This phase enables acquisition of grounding response measurements under a second directional excitation condition.
As with the forward excitation phase, the reverse excitation response may initially exhibit transient electrical behavior arising from switching transitions, interface response, charge redistribution, soil stabilization effects, and related time-dependent phenomena. Measurement acquisition is therefore performed after the response becomes sufficiently stable for reliable evaluation.
Accordingly, the measurement sequence (320) establishes a bidirectional timed excitation architecture in which forward excitation and reverse excitation are separated by a controlled temporal interval to improve measurement reliability.
Following completion of the bidirectional excitation sequence, the system performs post-processing and decision functions (340).
A combine forward and reverse measurements stage (345) receives measurement results obtained during the forward excitation phase and reverse excitation phase. These measurement results may be subjected to comparative validation, consistency evaluation, averaging, directional bias reduction, transient error rejection, or equivalent bidirectional measurement assessment.
Following measurement combination, a grounding resistance determination stage (350) determines a grounding resistance value representative of the grounding condition associated with the monitored installation.
The determined grounding resistance value may be supplied to an environmental compensation stage (355), which compensates or normalizes the resistance value based on environmental conditions that may influence grounding behavior, including temperature, humidity, soil moisture, or related environmental parameters affecting soil conductivity.
In certain implementations, environmental normalization may be performed using a compensation relationship in which the determined grounding resistance value is adjusted relative to one or more reference environmental conditions, including reference temperature, reference humidity, or reference soil moisture conditions. An example normalized resistance relationship may be expressed as:
Rnormalized = f(Rmeasured, T, H, M)
where Rnormalized represents normalized grounding resistance, Rmeasured represents measured grounding resistance, T represents temperature, H represents humidity, and M represents soil moisture.
The compensation function may be predetermined, calibrated, empirically derived, or adaptively updated based on installation-specific behavior.
Following environmental compensation, the processed resistance information is supplied to an abnormality detection stage (360) configured to evaluate grounding condition using threshold comparison, trend analysis, rate-of-change analysis, baseline comparison, anomaly detection, or related diagnostic evaluation.
Detected abnormalities may include corrosion, degradation of grounding conductors, grounding disconnection, earthing strip failure, theft of grounding conductors, soil dryness effects, surge-induced damage, open-circuit conditions, loose grounding connections, or other grounding integrity faults.
Abnormality determination may be based on absolute threshold exceedance, deviation from a stored baseline resistance value, rate-of-change evaluation across successive measurement cycles, trend analysis over historical measurement intervals, or combinations thereof.
Processed measurement data may be supplied to a data storage stage (365), where timestamped measurement values, processed resistance values, diagnostic status information, environmental parameters, alert events, and associated operational records may be stored for historical analysis and predictive maintenance purposes.
Measurement and diagnostic information may then be supplied to a communication module (370) configured to transmit operational information, alerts, diagnostic data, and measurement information to external monitoring infrastructure.
The communication module (370) communicates with a remote monitoring system (375), which may comprise a supervisory control and data acquisition platform, cloud monitoring infrastructure, utility monitoring center, transformer monitoring platform, or equivalent centralized monitoring architecture.
The remote monitoring system (375) may provide real-time monitoring, alarm management, historical trend analysis, predictive maintenance support, centralized infrastructure visibility, analytics generation, and reporting functions.
FIG. 3 further illustrates repeated execution of the measurement sequence (320) under control of the control and timing manager (310). The complete sequence may be executed periodically, continuously, at configurable intervals, upon occurrence of triggering events, or according to operator-defined measurement schedules.
Repeated execution of the measurement sequence enables continuous or interval-based monitoring of grounding integrity while maintaining controlled timing separation between directional measurement operations, because measurement acquisition is coordinated with controlled excitation timing and stable measurement intervals, asynchronous electrical disturbances including ambient electromagnetic noise, stray currents, switching disturbances, and transient electrical interference may be substantially reduced in influence compared to uncontrolled measurement acquisition.
Accordingly, FIG. 3 illustrates the controlled timing architecture (300) through which bidirectional excitation sequencing, transient isolation, grounding resistance determination, post-processing evaluation, abnormality detection, data management, communication, and remote monitoring are coordinated for grounding integrity monitoring.
Figure 4 illustrates a method (400) for monitoring grounding integrity of an energized electrical installation using controlled DC excitation-based grounding resistance measurement. The illustrated method represents an operational sequence through which grounding resistance may be determined and evaluated for identifying grounding degradation, abnormal grounding conditions, or deterioration in grounding system performance.
The method begins at step (405), wherein a controlled DC excitation signal is applied between a first grounding node and a second grounding node associated with the energized electrical installation.
The energized electrical installation may comprise a power distribution transformer, ring main unit, substation equipment, industrial electrical infrastructure, or other grounded electrical equipment requiring grounding integrity monitoring. The first grounding node may correspond to a transformer earth connection, equipment grounding point, grounding conductor connection, grounding electrode interface, or other grounding connection associated with the electrical installation. The second grounding node may correspond to a neutral earth connection, ground reference point, secondary grounding electrode, or another grounded reference connection.
Application of the controlled DC excitation signal establishes a conductive current path through the grounding system between the first grounding node and the second grounding node. The controlled DC excitation signal may be generated by a controlled excitation circuit configured to provide regulated voltage-controlled excitation, current-controlled excitation, pulse-controlled excitation, interval-based excitation, or equivalent controlled excitation suitable for grounding resistance determination.
The use of direct current excitation enables evaluation of the resistive component of the grounding path while substantially avoiding reactive impedance contributions commonly associated with AC-based measurement methods.
At step (410), the method includes measuring one or more electrical parameters associated with the applied excitation signal.
Measured electrical parameters may include voltage response, current response, voltage drop across the grounding path, excitation current magnitude, derived resistance-related response values, or equivalent measurable electrical characteristics associated with the grounding path. Measurement may be performed using voltage sensing circuitry, current sensing circuitry, analog front-end circuitry, signal conditioning arrangements, analog-to-digital conversion stages, or equivalent acquisition architecture.
One or more measurements may be acquired during the initial excitation condition, and sampled electrical values may be filtered, validated, or otherwise processed for subsequent analysis.
At step (415), the method includes reversing polarity of the controlled DC excitation signal between the first grounding node and the second grounding node.
Polarity reversal changes the effective direction of current flow through the grounding path. In a first operational condition, the first grounding node may be associated with a first excitation polarity while the second grounding node is associated with an opposite excitation polarity. Following polarity reversal, the polarity relationship between the grounding nodes is reversed, thereby causing current flow through the grounding path in an opposite direction.
Bidirectional excitation improves measurement reliability by allowing evaluation of grounding response under both current flow directions. Practical grounding systems may exhibit directional response variations due to contact resistance variation, soil non-uniformity, connector conditions, localized degradation, grounding interface effects, electrochemical response behavior, or installation-specific grounding characteristics. Measurement under both excitation directions therefore reduces directional bias and improves reliability of grounding resistance determination.
At step (420), the method includes measuring one or more electrical parameters associated with the reversed excitation signal.
Following polarity reversal, electrical response generated under the reversed excitation condition is measured to obtain additional measurement data corresponding to the opposite current flow direction through the grounding path. Measurements obtained during the reversed excitation condition may similarly include voltage response, current response, derived resistance-related values, or equivalent measurable electrical parameters associated with the grounding path.
At step (425), the method includes determining whether the measured electrical parameters satisfy a substantially stable measurement condition.
Immediately following excitation application or polarity reversal, transient response behavior may occur due to switching effects, capacitive settling, charge redistribution, electrochemical interface behavior, soil response stabilization, or other time-dependent disturbances. Accordingly, grounding resistance determination is deferred until the measured electrical parameters satisfy a substantially stable measurement condition suitable for reliable evaluation.
Determination of the substantially stable measurement condition may be based on elapsed timing criteria, voltage stabilization behavior, current stabilization behavior, rate-of-change analysis, resistance convergence behavior, or equivalent stabilization assessment techniques.
Where the measured electrical parameters do not satisfy the substantially stable measurement condition, the method may defer grounding resistance determination, continue sampling, repeat excitation, discard unstable measurements, or reinitiate the measurement cycle until a reliable measurement condition is achieved.
At step (430), the method includes determining a grounding resistance value based on the measured electrical parameters.
Grounding resistance determination may be performed based on electrical parameters measured under the initial excitation condition and the reversed excitation condition. Measurements obtained under both excitation directions may be combined, validated, compared, averaged, or otherwise processed to determine a representative grounding resistance value.
Grounding resistance determination may further include rejection of invalid measurements, filtering of transient disturbances, consistency verification, threshold validation, repeated measurement execution, or equivalent processing where unreliable measurement data is detected.
In certain implementations, the determined grounding resistance value may be compensated or normalized based on environmental parameters affecting grounding behavior.
At step (435), the method includes evaluating grounding integrity based on the determined grounding resistance value.
Grounding integrity evaluation may include comparison of the determined grounding resistance against threshold values, baseline values, historical measurements, trend behavior, or rate-of-change criteria.
The evaluation process may identify abnormal grounding conditions including corrosion of grounding electrodes, earthing strip degradation, grounding conductor breakage, theft of grounding conductors, soil dryness-induced resistance increase, surge-induced grounding damage, loose grounding connections, open-circuit conditions, or other grounding integrity abnormalities.
For example, where successive measurement cycles indicate a progressive increase in grounding resistance from a previously established baseline value, the method may determine that degradation of the grounding system has occurred. The degradation may be associated with corrosion of grounding electrodes, deterioration of earthing strips, degradation of grounding conductors, loosening of grounding connections, reduction in soil conductivity, surge-induced damage, or physical removal of grounding components. In response to such determination, the method may generate alerts, maintenance notifications, or diagnostic reports for corrective action.
Grounding integrity evaluation may further include classification of abnormal conditions based on measurement behavior, temporal trends, threshold exceedance characteristics, environmental correlation analysis, or equivalent diagnostic criteria.
Where abnormal grounding conditions are identified, the method may further include generation of alert notifications, storage of diagnostic information, communication of abnormality data to remote monitoring systems, and initiation of maintenance response workflows.
The method (400) may be repeated continuously, periodically, at scheduled intervals, upon operator request, or in response to detected electrical events requiring grounding reassessment.
Accordingly, FIG. 4 illustrates an operational method (400) through which controlled bidirectional DC excitation, bidirectional electrical parameter measurement, stability validation, grounding resistance determination, and grounding integrity evaluation are performed for monitoring grounding systems associated with energized electrical installations. ,CLAIMS:We claim:
1. A grounding resistance measurement and monitoring system, the system comprising:
a controlled DC excitation module configured to apply an excitation signal between a first grounding node and a second grounding node associated with an energized electrical installation;
a polarity reversal module configured to selectively reverse polarity of the excitation signal between the first grounding node and the second grounding node;
a sensing module configured to measure one or more electrical parameters associated with the applied excitation signal;
a processing unit operatively coupled to the sensing module and configured to:
determine a grounding resistance value based on the measured electrical parameters; and
evaluate grounding integrity based on the determined grounding resistance value.

2. The system as claimed in claim 1, wherein the controlled DC excitation module is configured to apply the excitation signal in one or more controlled time intervals separated by one or more non-measurement intervals.

3. The system as claimed in claim 1, wherein the processing unit is configured to determine the grounding resistance value after identifying a substantially stable measurement condition following application of the excitation signal.

4. The system as claimed in claim 3, wherein the processing unit is configured to identify the substantially stable measurement condition based on a rate of change of one or more measured electrical parameters and/or a derived resistance parameter.

5. The system as claimed in claim 1, wherein the processing unit is configured to determine the grounding resistance value based on measurements obtained during excitation in a first polarity condition and a reversed polarity condition, including comparative validation, averaging, or consistency evaluation of the measurements.

6. The system as claimed in claim 1, further comprising one or more environmental sensing modules configured to detect environmental conditions associated with the energized electrical installation, wherein the processing unit is configured to compensate or normalize the determined grounding resistance value based on the detected environmental conditions.

7. The system as claimed in claim 1, further comprising an abnormality detection module configured to identify grounding degradation based on threshold comparison, trend analysis, baseline comparison, or rate-of-change analysis of the determined grounding resistance value.

8. The system as claimed in claim 1, further comprising a communication module configured to transmit grounding condition data, abnormality information, diagnostic data, or alert information to a remote monitoring system.

9. The system as claimed in claim 1, further comprising a protection and/or isolation module configured to provide electrical isolation, current limiting, surge protection, overvoltage protection, or fault isolation for safe operation of the system.

10. A method for monitoring grounding integrity of an energized electrical installation, the method comprising:
applying a controlled DC excitation signal between a first grounding node and a second grounding node associated with the energized electrical installation;
measuring one or more electrical parameters associated with the applied excitation signal;
reversing polarity of the controlled DC excitation signal between the first grounding node and the second grounding node;
measuring one or more electrical parameters associated with the reversed excitation signal;
determining whether the measured electrical parameters satisfy a substantially stable measurement condition;
determining a grounding resistance value based on the measured electrical parameters associated with the applied excitation signal and the reversed excitation signal, upon determining that the substantially stable measurement condition is satisfied; and
evaluating grounding integrity based on the determined grounding resistance value.