ZnO Surge Arresters Research Articles

Influence of impulse corona discharge on discharge time lag of a surge arrester with a spark gap

ZnO surge arrester with a spark gap is used for reducing electrical failures in power distribution systems of Japan. The high responsiveness, the low residual voltage, and the stable operating voltage are required for the arresters. However, the discharge time lag generally occurs in a spark gap. In this study, measurements of V-t characteristics and observations of optical emissions from impulse corona discharges generated at a newly designed small step edge on an inclined plane of each electrode were carried out. The small step edge made the discharge time lag and the standard deviation small. Based on the results, we indicated that the impulse corona discharge improves the discharge time lag of the sparkover.

Thermal FEM Analysis of Surge Arresters During HVdc Current Interruption Validated by Experiments

This paper deals with the development of an accurate finite-element model of an arrester to investigate the electrothermal and mechanical stress during dc current interruption. The comprehensive analysis performed on a ZnO surge arrester is supported by experiments during high-voltage dc circuit breaker current interruption. The performed experimental analysis comprises three sequential 26 kV/10 kA direct current interruption tests carried out within a period of one hour. The dynamic temperature and current distribution of the surge arrester columns during current interruption are measured. The finite-element simulation results are in good agreement with the test results. The influence of the surge arrester temperature on the current distribution among the surge arrester columns is analyzed. The impact of the surge arrester temperature on ZnO electrical characteristics and mechanical stress inside the surge arrester are also investigated. The surge arrester finite-element model can be used with full success for parameter optimization of the surge arresters to prevent possible failures when dc circuit breakers performed multiple interruptions in short period of time.

Various Methods for Measurement of Resistive Leakage Current of Metal Oxide Surge Arrester

Metal Oxide Surge Arrester (MOSA) does not require any ordinary maintenance. But MOSA is get affected from ageing due to the effect of discharging impulse currents, uneven heating and internal partial discharges. A leading cause of deterioration is ingress of moisture. The degradation of MOSA also correlated with the ageing level of the arrester. This is called degradation under surge. The ageing level with the degradation of MO surge arrester or the leakage current of the surge arrester is related to each other. The leakage current is directly proportional to the ageing level. If the ageing level is raise, the leakage current also will increase. So, various methods for determination of the condition of ZnO surge arrester by means of measurement of the arrester leakage current are discussed. A MSCM method, which is based on leakage current of the surge arrester presented. The measuring instrument Leakage Current Monitor is also discussed.

Towards the prospection of an optimal thermal response of ZnO surge arrester in HV power system

In order to understand the thermal and electrical properties of surge arrester under standard climatic conditions, it would be useful to evaluate the heating progression in its different elements. These are constituted of heterogeneous materials, which have physical and electrical nonlinear properties along the surge arrester. Temperature predicting solutions for zinc oxide ceramic blocks provide fundamental elements of the electrothermal material characteristics in view of the lifetime estimation. Electrothermal phenomenon analysis of surge arresters is based on empirically-determined parameter models, using finite element method (FEM) simulated on COMSOL Multiphysics software which is a more precise approach compared to the existing models. In this paper, the behavioural model has been developed to study the surge arresters in both cases: the steady state and overvoltage state (lightning). Previous published works validate the first simulation results. This work is therefore extended to consider other operating states, which illustrate the dependence of the type of surge on the amplitudes and durations of electrothermal phenomena.

Development of a Model for Calculation of Energy Absorbed by a ZnO Surge Arrester During Transients

Several models were successfully developed to reproduce the dynamic behavior of ZnO surge arrester, but the accuracy and reliability of these models are only evaluated for residual voltage calculations. This paper presents a model developed with the specific goal of achieving reliable and accurate modeling of the energy absorbed by a ZnO surge arrester during impulsive transients. To develop and test the model, an experimental database was built, composed of responses of ZnO varistors to current impulses. The database contains the response of varistors of different classes and manufacturers, subjected to current impulses with different waveforms and amplitudes. Then, using system identification techniques, a mathematical model was proposed and validated. The proposed model was successfully tested on the same circumstances that traditional models are used and its performance was compared with the most relevant existing ZnO model. The results indicate that the developed model is an overall valid model for ZnO surge arresters and that energy calculations performed with it are more accurate and reliable.

Study on the thermal behaviour and non‐linear coefficient of the 10 kV ZnO surge arrester

The thermal behaviour of the surge arrester is vital to assess its operational condition. The surge arrester usually shows a process of temperature rising during a long-term operation, particularly after subjecting to a surge. Therefore, the research on the temperature characteristics of ZnO arresters contributes to achieve the goal of the performance changes of the ZnO arresters over different temperatures. In this study, based on four types of ZnO arresters from different factories, the variation of the volt–ampere curve, DC characteristic parameters and non-linear coefficient of the whole ZnO arrester at different temperatures were analysed. The relationship between the temperature and non-linear coefficients was obtained through the method of the extraction of the non-linear coefficients. Through the multiple impulse current tests, the temperature of the arrester was well calculated by measuring the corresponding volt–ampere curve, and the relationship between the surface temperature and V–I characteristics of the arrester is verified by the impulse test results. The obtained results provide a new idea for the application of the surface temperature of the arrester in the performance monitoring of the arrester.

Thermal behaviour analysis in a porcelain‐housed ZnO surge arrester by computer simulations and thermography

In this article, an analysis of heat transfer in a porcelain-housed ZnO surge arrester is presented. Due to the fact that ZnO-based surge arresters are key components for protection and reliability of electrical systems, it is necessary to seek techniques to assure correct assessment. In porcelain-housed arresters, the air gap leads to an increased thermal resistance between the ambient and the varistor column. Consequently, a thermal analysis must consider convection and radiation heat transfer mechanisms, besides heat conduction. This study proposes the use of computational simulations in combination with thermography as a tool for a temperature-based estimation of the varistor state. For the analysis, temperature rise tests were performed in a 69-kV ceramic-housed arrester to measure material emissivity and produce data to fit the simulated response. Furthermore, the thermal response of the surge arresters subject to an impulsive energy input was evaluated. The simulations allow to relate varistors temperature and housing temperature with regard to a specified amount of dissipated power. The obtained results show that the used technique can be an effective method for arrester monitoring and may allow to define assessing criteria for a porcelain-housed arrester based on housing temperature measurements.

Optimisation of zinc oxide surge arrester design using gravitational search algorithm and imperialist competitive algorithm

Reducing electric field stress near the energised end of surge arresters is very important because it may increase the lifetime of the highly stressed ZnO column in vicinity of the high voltage electrode. Most of previous works were based on manufacturers’ procedures and trial and error method to improve the surge arrester designs. In this work, optimisation of ZnO surge arrester design models using Gravitational Search Algorithm (GSA) and Imperialist Competitive Algorithm (ICA) is proposed. The surge arrester models were developed using finite element analysis (FEA) and used to determine the electric field distribution. The optimisation methods were used to determine the arrester design parameters which yield the minimum electric field stress surrounding the energized end of the surge arresters. GSA is less complex since it requires only two parameters to be adjusted i.e. mass and velocity while ICA demonstrates faster convergence and better achievement of global optimum. The performance of the proposed methods was then compared with the manufacturer’s test data and previously developed methods.

Prediction of ZnO Surge Arrester Degradation Based on Temperature and Leakage Current Properties

Temperature and leakage current on the ZnO arrester are interrelated with each other. In low conduction region, voltage-current characteristics of ZnO surge arrester are highly dependent on temperature. The leakage current will increase as the temperature increases and experience thermal runaway when the temperature exceeds the acceptable limit. This phenomenon is associated with the increase of resistive leakage current due to degradation. Therefore the temperature and leakage current are good indicator to evaluate the condition of ZnO arrester. This paper proposed the degradation prediction of ZnO surge arrester by analyzed the temperature and leakage current. The 132 kV station type ZnO surge arrester was employed. Temperature profile of ZnO arrester was obtained using thermal camera. The leakage current was measured simultaneous with the temperature measurement to attain the leakage current at the actual temperature. The results shows the leakage current continue increasing by increasing the temperature. Keywords : Resistive leakage current, temperature, degradation, prediction, zinc oxide surge arrester

新幹線き電用避雷器の多頻度動作と新しい動作カウンターの提案

新幹線き電用避雷器の多頻度動作と新しい動作カウンターの提案

Development of a Detection Device For Deteriorated ZnO Surge Arresters at AC Traction Substations

Development of a Detection Device For Deteriorated ZnO Surge Arresters at AC Traction Substations

Estimation of Critical Resistive Leakage Current of polymer housed ZnO surge arrester by electro-thermal modelling

In this study, a MATLAB/Simulink software based electro-thermal model of the polymer housed, gapless, 60kV ZnO surge arrester is used for estimating the ‘ Critical Resistive Leakage Current (CRLC)’. The electrical model is obtained by conducting experiments on a representative ZnO element at various voltages and temperatures which yields voltage–current–temperature (V–I–T) and power loss–voltage–temperature (P–V–T) characteristics. The thermal model represents the thermal properties of the arrester components as an electrical analogous circuit made of resistance & capacitance. The power loss calculated by the electrical model is the input to the thermal model. The electrical and thermal models run for numerous iterations until the arrester goes to thermal runaway or until it reaches a stable element operating temperature. The electro-thermal model is used to determine the two intersection points (stable operating point and the thermal instability point) of the power input and heat loss curves. The authors have proposed a new criteria based on detection of occurrence of the highest segmental slope inbetween the lower stable operating point and upper instability point on the power input curve (P–V–T characteristics) to estimate the CRLC. In order to sensitise the maintenance personnel about the level of deterioration and imminent failure of the arrester in the near future a warning in the form of the Observation Current (OBCUR) is also proposed. The easy to follow procedures for estimating the CRLC and OBCUR and the results obtained for two different arresters (of two different manufacturers) are presented in this paper.

Analysis of Leakage Current on 11kV Zinc Oxide Surge Arrester Using Finite Element Method

Leakage current is known to be directly related to the degree of degradation of arrester. Leakage current is commonly flow across arrester under non-conducting condition. In this work, a two-dimensional (2D) axial-symmetrical 11kV surge arrester model was developed and used to simulate the leakage current under normal condition. The influence of insulator shed widths, housing materials and sizes of ZnO in an 11kV ZnO surge arrester design on its leakage current was studied using finite element method (FEM) software, which is COMSOL Multiphysics. The simulation results show that leakage current is mostly affected by the sizes of the ZnO and material of the housing. From this work, an understanding on the leakage current behaviors in a ZnO surge arrester can be enhanced. This study may also help in improving the design of surge arresters in reducing leakage current.

Effect of Ambient Temperature Zinc Oxide Surge Arrester Condition Monitoring

Various methods have been developed to monitor surge arrester condition and predict the probable interruption which can be caused by the failure of surge arresters. This paper aims to carry out experimental and simulation work to find the relationship between the aging level, arrester surface temperature and ambient temperature. COMSOL simulation software was used for the modeling of 120kV rated gapless ZnO surge arresters. It is observed from both the simulation analysis and experimental data that the leakage current and temperature increase as a consequence of an increase in the applied voltage across the arrester. The thermal profile of the ZnO surge arrester changes depending on the aging level and the ambient temperature. The surface temperature simulation results compare well with the experimental results, for the case of varying aging levels.

Thermal Image and Leakage Current Diagnostic as a Tool for Testing and Condition Monitoring of ZnO Surge Arrester

This paper presents a study proposing a method to assess the condition of metal-oxide surge arresters. Thermal data using thermal imaging as well as the leakage current third harmonic component were used as tools to investigate the surge arrester aging condition. Artificial Neural Network was employed to classify surge arrester condition with the temperature profile, ambient temperature and humidity as inputs and third harmonic leakage current as target. The results indicated a strong relationship between the thermal profile and leakage current of the surge arrester. This finding suggests the viability of this method in condition monitoring of surge arrester.

Diagnostic of silicon carbide surge arresters using leakage current measurements

Nowadays, the zinc oxide surge arresters (ZnO) are widely used in power systems, however, a large number of silicon carbide surge arresters (SiC) are still in service in the utilities. On the other hand, it is not possible to replace all SiC surge arresters in a short time period, being necessary to review the maintenance program taking into account the surge arresters that are more degraded. In this context, a research project was established between the University of São Paulo and the electrical utility CTEEP, aiming the investigation of its SiC surge arresters. This work shows that the leakage current measurement, a common diagnostic method for the ZnO surge arresters, can provide useful information related to the condition of the SiC surge arresters. Analysis of amplitude and distortion of the leakage current, also considering thermovision measurements, result in better evaluation of the SiC surge arresters.

The Creative, Originative, and Useful Progress of Surge Arresters and Insulation Coordination for AC 66–1100 kV Power Systems Described in the IEEJ Technical Report No. 1132

AbstractIt is essential to prove that the technology of metal (zinc) oxide surge arresters born in Japan is very creative, originative, and useful to insulation coordination for power systems. Surge arresters investigating R&D Committee of Japan have summarized ‘power technology of Japan through the experience of developments and applications of surge arresters—AC 3.3–1100 kV and HVDC 125–600 kV power systems’. This technical report No. 1132 describes lightning phenomena, manufacturing of ZnO elements, surge arresters and insulation coordination for AC 3.3–550 kV, 800 kV, 1100 kV substations, 22–500 kV transmission lines, power cables, HVDC 125–DC 600 kV systems, 6.6–33 kV distribution lines, 100–200 V surge protective devices, and maintenance methods. This paper describes that the creative, originative and useful progress of metal (zinc) oxide surge arresters contributes drastically to the insulation coordination for AC 66–1100 kV power systems. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Analysis of thermal and electrical properties of ZnO arrester block

Voltage–current characteristics of ZnO surge arresters are highly dependent on temperature in the low-conduction region. ZnO surge arresters experience thermal runaway when the temperature exceeds the acceptable limit. This phenomenon is associated with the increase of resistive leakage current due to degradation. This paper presents the thermal and electrical characteristics of ZnO arrester blocks under the power frequency AC operating voltages. The leakage currents of ZnO arrester blocks were measured over a period of the time. The temperature profiles of ZnO arrester blocks were observed by the infrared camera. The degradation and the thermal runaway of the ZnO arrester blocks are closely related to the temperature limit which determines the heat generation and dissipation. As the leakage current was 0.5 mA, the amount of heat generation is lower than that of heat dissipation. So temperature of the ZnO arrester blocks was rarely changed. On the other hand, as the leakage current was 0.7 and 1 mA, the amount of heat generation was greater than that of the heat dissipation. The temperature of ZnO arrester blocks gradually increases and the test specimen experiences thermal runaway. At that time the temperature located at the center of ZnO arrester blocks string was higher compared to that of ZnO block at both edges.

Measurement of the resistive leakage current in surge arresters under artificial rain test and impulse voltage subjection

Surge arresters are installed on transmission and distribution lines and in substations between phase and earth in order to improve the lightning performance and reduce the failure rates. High-energy stresses and housing deterioration are the main factors of degradation and damage of surge arresters. Thus, there is need for testing and monitoring the electrical network's arresters, in order to verify their good condition and their ability to effectively protect the lines. The most common method used, is the measurement of the arresters' total leakage current (with the isolation of the resistive part), which is an indicator of the arrester's condition, since every change, deterioration or damage leads to an increase of the resistive leakage current. In the current work, the total leakage current of two 20 kV ZnO surge arresters without gaps is measured and the resistive component for three different cases (brand new arresters, measurements under artificial rain and measurements after impulse voltage subjection) is computed. The analysis of the produced results can be useful in correct diagnosis of arresters' condition and in more effective schedule maintenance, since any recorded high-resistive currents do not necessarily result arrester's repair or replacement.

뇌임펄스전류에 의한 ZnO 피뢰기의 열화특성

이 논문은 뇌임펄스전류의 입사에 따른 ZnO 피뢰기의 열화 특성에 대하여 기술하였다. 뇌서지에 의한 ZnO 피뢰기의 열화특성을 분석하기 위해 시료 ZnO 피뢰기에 8/20[㎲], 2.5[㎄]의 표준뇌임펄스전류를 인가하였다. 뇌임펄스 전류를 인가한 것과 인가하지 않은 ZnO 피뢰기에 흐르는 상용주파수 AC 및 DC 누설전류를 측정하였다. 그 결과 임펄스전류의 인가횟수가 증가함에 따라 누설전류는 증가하였고 AC전압에서 누설전류의 비대칭성은 뚜렷하게 나타났다. 뇌임펄스전류를 인가하지 않은 ZnO 피뢰기의 ZnO 입자는 균일한데 반해 뇌임펄스전류를 인가한 ZnO 피뢰기의 ZnO 입자는 불균일하게 변형되었다. 또한 뇌임펄스전류 인가에 따른 Bi<SUB>2</SUB>O<SUB>3</SUB>의 감소가 입계층의 결핍을 발생시키며 입계층의 결핍에 의한 전류의 집중이 ZnO 피뢰기 소자의 비선형 특성의 열화에 대한 중요한 요인으로 작용한 것으로 밝혀졌다.