Some Explanations About the Chaos in the Selection of EGLA for 10 kV AC Lines
In order to clarify the current industry blindly increase the rated voltage value and compression residual voltage value of the series varistor unit of EGLA,confuse the power frequency wet withstand volt-age requirements after the SVU failure,and use the disconnector in conjunction with the EGLA.It is ex-plained in the way of theoretical analysis combined with experimental demonstration:Firstly,the rated voltage of a typical 10 kV externally gapped line arrester of 13 kV can meet the safety requirements of the arrester itself.Blindly increasing the rated voltage cannot significantly improve the surge arrester's ability to withstand high current impulse,and will also affect the coordination with the gap performance.Sec-ondly,the residual voltage value of a typical 10 kV externally gapped line arrester of 40 kV can fully meet the lightning protection requirements of the line,and which has a large margin.It is meaningless to in-crease the residual voltage requirement value.Thirdly,the EGLA power frequency wet withstand voltage requirement value should not be lower than 1.2 times the highest power frequency overvoltage of the sys-tem when the body of the SVU fails.It is not simple to apply the expression "1.2 times the rated volt-age"to calculate.Fourthly,it is unscientific to try to achieve "double insurance"with the disconnector on the EGLA.The series gap of the line arrester has realized the isolation function under the condition of the SVU fault,and the power frequency freewheeling current of the arrester can also be interrupted within half a cycle,and there is no short-circuit current and its duration of the disconnector action.Arbitrarily connecting the disconnector in series with the line arrester will occupy the resources of the transmission corridor,increase the line lightning protection cost,and increase the line operation and maintenance bur-den.
EGLArated voltageresidual voltagepower frequency withstand voltage
万方数据
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