The correct operation of surge arresters under lightning and switching transient conditions requires that grounding be effective at high frequencies as well as at power system frequency. Effective high frequency grounding also limits the electrocution risk to substation personnel due to transient ground potential rise. This article assesses the performance of high frequency electrodes at typical lightning impulse current magnitudes. The enhancement of such electrodes by addition of bonded horizontal arms in cross and star arrangement is also investigated. The effective impulse resistances for electrodes having lengths up to 4.8 m are calculated over a range of impulse current magnitudes at the same location. The results obtained indicate that, for low impulse current magnitudes, the preionization electrode's resistance ( R ₁ ) falls with increasing rod length, a behavior reflected in the measured dc resistance. The presence of horizontal enhancement was found to reduce R ₁ in all cases. The occurrence of soil ionization in the immediate vicinity of the electrode resulted in a reduced postionization resistance ( R ₂ ) at higher currents, tending toward a common asymptotic value independent of both the length of the rod and the presence of electrode enhancements. The observed behavior is supported by numerical simulation of electric field and current density distributions, indicating that the high current performance of a grounding rod is heavily influenced by soil ionization and breakdown in high-field regions at the electrode extremities.

中文翻译：

---

常规和增强棒接地电极的雷电流性能

避雷器在雷击和开关瞬态条件下的正确操作要求接地在高频和电力系统频率下有效。有效的高频接地还限制了由于瞬时接地电位升高而给变电站人员带来的触电风险。本文评估了高频电极在典型雷电冲击电流幅度下的性能。还研究了通过添加交叉和星形排列的粘合水平臂来增强这种电极。长度达 4.8 m 的电极的有效脉冲电阻是在同一位置的脉冲电流幅度范围内计算的。获得的结果表明，对于低脉冲电流幅值，预电离电极的电阻 ( R ₁ ) 随着杆长度的增加而下降，这种行为反映在测得的直流电阻中。发现水平增强的存在可以减少R ₁在所有情况下。在电极附近发生土壤电离导致定位电阻降低（ R ₂ ) 在更高的电流下，趋向于一个共同的渐近值，与杆的长度和电极增强的存在无关。观察到的行为得到电场和电流密度分布的数值模拟的支持，表明接地棒的高电流性能受到电极末端高场区域土壤电离和击穿的严重影响。