绝缘堆为PTS装置的核心部件之一，其工作性能很大程度上决定了PTS装置整机的运行状态。在前期整机调试的基础上，对PTS装置绝缘堆的工作性能进行了介绍与初步分析。基于真空沿面闪络的统计学经验公式和瞬态电磁波分析方法，对实验中出现的两种典型异常电压波形的原因进行了探讨，初步验证了环间闪络引起的瞬态电磁波在绝缘堆内部不同介质中传输、衰减与合成的规律。实验表明，在最高2 MV的工作电压下近30发的实验中，绝缘堆未出现贯穿性闪络现象。在实验中也观测到，随着发次的累积，绝缘堆的环间闪络会在随机分布的基础上呈现一定的系统性偏差。

No whole-stack flashover has been observed under the working voltage of about 2 MV in the PTS vacuum insulator stack, because of the uniform voltage distributions on different insulator rings, the effects of azimuthal transit-time and multi-stage structure. In this paper, two typical abnormal voltage waveforms are interpreted to be caused by the different flashover locations. The experimental results preliminarily validate the rules of transmission, attenuation and composition of transient electromagnetic waves in different mediums, caused by flashover. The stochastic occurrence of flashover presents a certain extent systemic discrepancy in two modules along with the increasing of experiment time, due to deposits accumulation on the surface of the insulator rings.