Insulation Reinforcement for Cable Connector of CRH2 Electric Multiple Unit Under Standard Lightning Impulse Voltage

In order to improve the insulation capacity of cable connector (Cc) in the high voltage equipment box (Hveb), this article proposes an optimization scheme that does not change the size of the Hveb and the structure of Cc fittings. In this article, the change in the impulse voltage withstand value of Cc after installing insulating sheath was verified by the lightning impulse flashover test. Based on the finite-element software and the structure of Cc fittings, a special shaped shielding ring (Sr) was designed to adjust the partial area where the electric field intensity are concentrated. Besides, the optimal parameters of the Sr under different working conditions were determined by the orthogonal design. Finally, utilizing ultraviolet (UV) imaging technology and image processing method, the discharge intensity of Cc fittings were characterized. The results demonstrate that with the combination of insulation measures, the impulse voltage withstand value of Cc can be increased from 155 to 235 kV. The maximum electric field strength on the surface of bolts and metal electrode can be reduced by 57.8% and 72%; UV discharge facular area had an exponential relationship with the applied voltage, the initial discharge voltage of Cc can increase by 243% after installing the Sr.