交流电压下典型平板油纸绝缘结构油流带电特性

Flow Electrification Characteristics of Typical Plane Oil-Pressboard Insulation under AC Voltage

为研究交流电压作用下油纸绝缘的油流带电特性,在实验室搭建了典型平板电极结构的油纸绝缘模型,利用密闭油循环系统开展了油流带电的试验研究,并探讨了交流电压作用下冲流电流与外施电压幅值及温度之间的关系。试验结果表明:无外施电压作用时,油纸绝缘冲流电流特性与温度及油流速度有关,低温下冲流电流随流速的增加呈线性增加;高温下冲流电流与流速呈幂函数的关系。在外施交流电压作用下冲流电流大小与外施电压的幅值有关,当交流电压幅值较低时冲流电流变化较小,而当外施电压幅值提升超过一定值后冲流电流随电压幅值升高而明显增大。温度对冲流电流有较大的影响,随温度的增加冲流电流呈指数增加,且流速较高时温度对冲流电流值影响更加明显。对试验结果的理论分析表明:外施交流电压下油流带电程度的提高应归因于纸中离子迁移对界面处电荷产生速度的促进;温度通过影响油纸绝缘中离子迁移和扩散速度以及电场分布而影响油流带电特性。

To investigate the flow electrification characteristics of oil-paper insulation under AC voltage, a typical plane oil-pressboard insulation structure was built in laboratory. Experiment study on flow electrification was carried out with the closed oil circulating system, and the relationships were also discussed among streaming current, the voltage amplitude and temperature under AC voltage. The results show that the flow electrification characteristics of oil-paper insulation are related to the temperature and flow velocity in the absence of an external energizing voltage. The streaming current increases linearly with flow velocity at low temperature. At high temperature, the streaming current and flow velocity have the relationship of power function. The streaming current is associated with the amplitude of the applied voltage under AC voltage. The streaming current changes little if the amplitude of AC voltage applied on the oil-paper insulation is low. After the applied voltage amplitude rises to a certain value, the streaming current increases obviously with the voltage amplitude. Temperature has great influence on streaming current. That is, the streaming current increases exponentially with the increase of temperature, and the influence of the temperature is even more obvious under high velocity. The theoretical analysis demonstrate that the increase of charging tendency under AC voltage can be attributed to the enhancement of charge generation speed at oil-paper interface by ions migration in the paper. The temperature influences the flow electrification characteristics through affecting the ions migration, diffusion speed, and the electric field distribution.