power system overvoltages due to switching, lightning and other disturbances are the main problem for designers of the power transformers. once some frequencies of the incoming surges match with some of the natural frequencies of transformer winding, the resonance phenomenon is expected in transformer winding. the resonant overvoltages may destroy the insulation between turns and cause to insul...

The consequences of zinc oxide (ZnO), Aluminum oxide ( 3 2O Al ) and Titanium oxide (TiO2) on tree growth have been comprehensively investigated in this paper. Zinc oxide (ZnO), II-VI compound semiconductor, is used in varistors in power insulation life. Due to its excellent electrical properties such as nonlinearity of current-voltage (I-V) characteristics, high fast-transient response and hig...

The housing of zinc oxide lightning arresters are playing major role for discharging the lightning surges. Previously porcelain and silicon rubber housings were mainly used depending on the atmospheric conditions but in practice a lot of problems are faced with these housing. Hence this paper presenting the ZnO blocks performance characterizes with different dielectrics such as air, transformer...

This paper presents impulse tests results on a zinc oxide (ZnO) surge arrester connected to four ground electrodes, with its resistance values ranging from 17 ? 104 ?. It has been noted that when in series various values, the voltage–current characteristics of are far one tested using common grounding, which is standard measurement method described IEC 60060-1. clarifies relationship between el...

Abstract When lightning intrudes into the over-voltage in 500 kV substation, wave will be introduced substation along line, which seriously affect insulation level of equipment. In this paper, firstly, working principle, characteristics, and current simulation ZnO arrester are described. Then, electromagnetic transient program (EMTP-ATP) used a GIS carried out research to over-voltage, specific...

Data on characteristics of metal-oxide surge arresters indicates that for fast front surges, those with rise times less than 8μs, the peak of the voltage wave occurs before the peak of the current wave and the residual voltage across the arrester increases as the time to crest of the arrester discharge current decreases. Several models have been proposed to simulate this frequency-dependent cha...

Metal oxide surge arresters (ZNO) are used widely in power system to protect equipments from over voltages. Non uniform potential distribution leads to the depressed service life and low safe reliability, so grading ring is applied on HV surge arrester order to uniform the electric field distribution. One of the problems of arresters is leakage current in power frequency that different paramet...

Metal oxide surge arrester accurate modeling and its parameter identification are very important for insulation coordination studies, arrester allocation and system reliability. Since quality and reliability of lightning performance studies can be improved with the more efficient representation of the arresters´ dynamic behavior. In this paper, Big Bang – Big Crunch and Hybrid Big Bang – Big Cr...

metal oxide surge arrester accurate modeling and its parameter identification are very important for insulation coordination studies, arrester allocation and system reliability. since quality and reliability of lightning performance studies can be improved with the more efficient representation of the arresters´ dynamic behavior. in this paper, big bang – big crunch and hybrid big bang – big cr...

The aim of this study is to propose simple and reliable techniques to assess the condition of metal oxide arrester based on the dielectric response techniques. A number of modern electrical diagnostics for Metal Oxide Surge Arrester (MOSA) are discussed in this paper. The techniques included return voltage, decay voltage and polarisation/depolarisation current measurement. The single and multip...