Electrical Trees and Their Growth in Silicone Rubber at Various Voltage Frequencies

Abstract

Abstract:The insulation property at high voltage frequencies has become a tough challenge with the rapid development of high-voltage and high-frequency power electronics. In this paper, the electrical treeing behavior of silicone rubber (SIR) is examined and determined at various voltage frequencies, ranging from 50 Hz to 130 kHz. The results show that the initiation voltage of electrical trees decreased by 27.9% monotonically, and they became denser when the voltage frequency increased. A bubble-shaped deterioration phenomenon was observed when the voltage frequency exceeded 100 kHz. We analyze the typical treeing growth pattern at 50 Hz (including pine-like treeing growth and bush-like treeing growth) and the bubble-growing pattern at 130 kHz. Bubbles grew exponentially within several seconds. Moreover, bubble cavities were detected in electrical tree channels at 50 Hz. Combined with the bubble-growing characteristics at 130 kHz, a potential growing model for electrical trees and bubbles in SIR is proposed to explain the growing patterns at various voltage frequencies.

Insulation Materials and Systems for Power Electronics Modules: A Review Identifying Challenges and Future Research Needs

“…To the best of our knowledge, the maximum frequency studied for electrical treeing degradation in the literature only reaches 130 kHz [42] and this was for silicone rubber (a solid dielectric) and not for silicone gel. It was observed that electrical trees tend to be denser and larger with rising frequency; when the frequency exceeds 100 kHz, bubble breakdown occurs in a very short time, as shown in Figure 7.…”

Electrical Tree Initiation and Growth in Silicone Rubber under Combined DC-Pulse Voltage

“…When the traditional tree generated from the bubble, its volume obviously decreased. It can be assumed that in the bubble stage, there is a lot of gas inside it [41] and the different probabilities of bubble tree can be explained by the inception mechanism shown in Figure 11. There may be some small cavities near the needle tip for two reasons: (1) the high Maxwell compressive force caused by the prestressing DC; or (2) different thermal expansion of SIR and needle tip [34].…”

Partial Discharge Simulation and Detection in 750V DC XLPE Cables

“…Partial discharge (PD) is a phenomenon which occurs when there is an electrical discharge within a localized area as stated in IEC 60270 [3]. These internal arcs promote the breakdown of insulation, forming electrical trees [4,5]. Once the electrical tree has threaded sufficiently deep, it will exposed the copper conductor to the environment, resulting in a cable failure and risk of current leakage to the tunnel platform [6].…”