中文摘要：

为了研究二次施压下XLPE电缆中电树枝的生长特性，采用短电缆金属针缺陷试验装置，研究XLPE电缆在12kV作用下生长的电树枝受二次施压（15kV）作用后新树枝的生长特性。研究结果发现，受二次施压电压和升压速度的影响，XLPE电缆绝缘层中会出现一种奇特的“丛一枝”状电树枝。且二次施压下．生长出的新树枝具有引发时间短、生长速度快、放电通道窄等特点。结果表明．二次施压对XLPE电缆中电树枝的二次弓l发和生长有较大影响，是加速电缆老化和击穿的重要因素。

英文摘要：

In order to understand the secondary growth characteristic of electrical trees in XLPE cables, we adopted the needle defects testing device to simulate partial discharge （PD） of XLPE cables, and to investigate the growth characteristic of the primary electrical trees under 15 kV secondary voltage. The primary electrical trees were originally formed under 12 kV. The results show that in the insulating layer of the XLPE cable strange ＂bush-branch＂ shape electrical trees appear due to the effects of secondary voltage and voltage increasing speed, and the new electrical trees exhibit such characteristics as short initiation time, fast growth rate and narrow discharge channel. Analysis demonstrates that the bush is initiated by first voltage, the branch is initiated by secondary voltage, and the growth of branch follows electric field direction with obvious discharge channel. Secondary voltage imposes significant influence on the secondary growth of electrical trees in XLPE cables, which is the main factor to accelerate cable aging and breakdown.