Static Resistance Measurements Research Articles

Intelligent Failure Diagnosis for Gas Circuit Breakers Based on Dynamic Resistance Measurements

Moving and fixed main and arc contacts used in circuit breakers (CBs) are prone to erosion with time and usage. Static resistance measurement and dynamic resistance measurement (DRM) are well-known noninvasive methods for the condition assessment of the contacts. Practically, the implementation of various failures on contacts of the CB is so difficult due to their placement in a high-pressure interruption chamber. This paper investigates the impacts of common failure modes such as erosion, disconnection, and misalignment of contacts on DRM profile through 3-D multiphysical simulation of the interruption chamber in the finite-element analysis software COMSOL. The model has been verified against experiments conducted on a 24-kV, SF6 CB with a high-resolution scope. The measured profiles indicate that DRM exhibits specific behavior with respect to each failure, e.g., the arc contact erosion leads to a change in the commutation point in DRM. The results have been organized into an intelligent failure diagnosis algorithm based on a set of DRM-based features. In the end, the performance of the proposed algorithm which could be suitable for smart grids is evaluated in the case of an experiment.

Analysis of alternative parameters of dynamic resistance measurement in high voltage circuit breakers

Throughout its lifetime, high-voltage circuit breaker (HVCB) contacts suffer from inevitable degradation processes, especially during the formation of electric arcs. Highly degraded contacts can reduce the current interruption capacity and increase the chances of operational faults, which might lead to considerable financial losses. Therefore, the use of efficient evaluating techniques is a key factor to achieve systems reliability. The dynamic resistance measurement (DRM) is a technique that can be used to evaluate the degradation level of HVCB' contacts. It stands out from the usual technique, static resistance measurement, by allowing the assessment of both the main contacts and the arcing contacts (ACs). Usually, the mean resistance or the area under the DRM curve is used to estimate the AC degradation. However, DRM is a non-standardised technique and there are no specified parameters to evaluate the real wear conditions. Therefore, an analysis of alternative parameters extractible from the DRM technique is presented in this study, such as amplitude and variance of the DRM curve. The results attest the possible use of more than one parameter for the continuous evaluation of HVCB ACs, characterising the DRM as a more complete and precise diagnosis tool.

The role of electrical anisotropy and effective conducting thickness in understanding and interpreting static resistance measurements in CFRP composite laminates

This study is focused on (i) the experimental characterization of the anisotropic electrical resistivity of carbon fiber reinforced polymer (CFRP) composites and (ii) the development and experimental validation of predictive finite element (FE) models of the electrical response in CFRP laminates based on the concept of the effective conducting thickness. Two experimental methods have been developed to characterize the anisotropic electrical resistivities in three principle directions for the CFRP composite laminates using a direct current source. One method utilizes a traditional 6-probe resistance scheme and the alternative point-type 4-probe method is based on a handheld probe device similar to the JIS K7194 standard for homogenous plastics. An extensive experimental study has been conducted to characterize the anisotropic electrical resistivities of 16-ply unidirectional and 16-ply symmetric cross-ply IM7/977-2 and 32-ply unidirectional IM7/977-3 composites using the developed methods. Exploiting the concept of the effective conducting thickness, which describes the effective depth of current penetration through the thickness of an electrically anisotropic material, a unique methodology is developed for constructing FE models of these highly anisotropic CFRP materials. The concept of effective conducting thickness was identified as a critical component in achieving accuracy of the FE results as well as recovery of experimental resistivity from the alternative point-type 4-probe method. The FE models have been validated using the experimental results on the CFRP specimens of varying layup and thickness, and the techniques developed in this work may lead to advancements in non-destructive techniques in the areas of electrical characterization and damage sensing.

Influence of pre-pulse in spot weld bonding of three-sheet steel stack-up

This paper presents a study on the influence of pre-pulse process by spot weld bonding of asymmetric three-sheet steel stack-ups. Two types of stack-ups were examined, consisting a combination of low carbon steel (DX51—1.0226) and ultra-high-strength steel (22MnB5—1.5528). Weld bonding of asymmetric stack-ups results in particular challenges. By using standard parameters, the effective welding current range is reduced. This is primarily due to the increased contact resistance caused by the adhesive application and the associated change in process behavior. The use of adjusted parameters has made it possible to increase process stability and thus the welding current range. The selected pre-pulse allows the conditioning of the adhesive-bonded stack-ups. In addition to the evaluation of the specific welding current ranges, investigations were also carried out using static resistance measurement and on-line measurement to evaluate the electrical energy during welding.

Novel high‐frequency‐based diagnostic approach for main contact assessment of high‐voltage circuit breakers

Maintenance and repair of circuit breakers (CBs) due to their protective role in the power systems is the centre of attention and assessing their condition is tremendously important. The interruption chamber of the CBs including main contacts is highly subjected to erosion over time due to friction, and excessive heat produced by an arc during the interruption of the currents. This study presents a new high-frequency (HF) non-intrusive diagnostic technique for the deterioration of contacts used in high-voltage CBs. The most striking result to emerge from the investigations is that the resonance frequency highly relies on the condition of contacts. The proposed approach is implemented in Computer Simulation Technology Studio Suite software and compared with the measured data obtained through the static resistance measurement. In addition, a HF model based on the transmission line theory has been developed for the interruption chamber of CBs. The comparison of the obtained results via a novel HF-based approach with the experimental data validates the feasibility and accuracy of this approach in analysing the ablation of contacts used in the interruption chamber of CBs.

Corrections to low-frequency resistance measurements of self-heated metal microstructures

The resistance of self-heated mesoscopic structures has been used for some time as a way to prove the characteristics of electrons and phonons in these systems. In this paper, the authors consider the differences between low-frequency dynamic and static resistance measurements of mesoscopic systems in the steady state. They present a general description of these non-equilibrium experiments, and discuss the connection to an integration procedure used to determine the differences between the two methods of resistance measurements. The authors have applied the analysis to electron-heating experiments and have shown that the difference between the static and dynamic resistance depends on the electron-phonon coupling and the acoustic coupling appropriate for the mesoscopic structure.

Electrical resistance as an indicator of fatigue

The dependence of the electrical resistance on strain and fatigue was analyzed for the case of electrical interconnections subjected to a sinusoidal strain. Measurements of the resistance change at the drive frequency and at twice the drive frequency provided greater sensitivity than static resistance measurements. Equations were developed to model the electrical resistance to second order in the strain. The resistance change gives a direct measure of the interconnect strain. The amplitude of the resistance change at twice the drive frequency was found to increase rapidly with fatigue. The ratio of the resistance change at twice the drive frequency to the change at the drive frequency was approximately 20% at low cycle fatigue failure. The ratio was suggested as a fatigue indicator for reliability analyses or for accelerated testing.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Characterization of self-heating effects in a superconducting bolometer with the superfluid helium film

The static and dynamic response characteristics of a thin-film aluminum superconducting transition-edge bolometer are presented with particular attention paid to self-heating effects. Criteria are developed for correct operation of the bolometer for heat-pulse detection and ’’in situ’’ tests are presented to meet these criteria in a given experimental arrangement. The use of the superfluid helium film near its onset transition and the propagation of Third sound waves within this film are shown to aid greatly the characterization of the bolometer response. The results indicate that in order to guarantee correct bolometer response both heat-pulse and static resistance measurements must be compared.