电缆本体中空间电荷的测量与特性

Space Charge Measurement and Characteristics in the Actual Cable

交联聚乙烯(XLPE)电力电缆本体中的空间电荷在其绝缘的老化和击穿过程中扮演着重要角色,因此研究电缆本体绝缘中空间电荷的分布具有重要的意义。研制了一套电缆本体空间电荷电声脉冲法的测量装置,通过升流器实现了电缆线芯温度的控制,模拟了电缆在实际运行过程中线芯的温度随流通电流的大小而变化的状态。利用该套装置研究了常温和不同线芯温度下电缆本体中空间电荷的分布特性。研究发现:电缆本体中的空间电荷随着加压时间的增加而增多,随着温度的升高而减少且上电极与下电极之间的时间差随之增加。短路处理可以消除绝缘中空间电荷,但消除过程缓慢且不彻底。

The space charge in the actual cross-linked polyethylene(XLPE) cable plays an important role in aging and breakdown of insulation. So it is important to research the distribution of space charge in cable's insulation. In this paper a new space charge measurement device is developed, which can be used for actual cable based on the principle of pulsed electro-acoustic method(PEA). The temperature of cable core is controlled with current-lifting device to simulate the cable operation state that the temperature of cable core varied with the magnitude of the current flowing. The distribution characteristics of space charge in cable under normal temperature and different temperature are analyzed with above measurement device. Test results show that the space charge in cable increases with the rise of applying DC voltage time, and decreases with rise of the temperature of cable, and also the time difference between top electrode and ground electrode increases with the rise of the temperature of cable. The space charge in insulation can be eliminated after a short circuit. However, the process of elimination is slow and space charge cannot be completely eliminated.