Charge Injection Characteristics of Semi-Conductive Composites with Carbon Black-Polymer for HVDC Cable.

Yanhui Wei,Guochang Li,Mingyue Liu,Chuncheng Hao,Wang Han,Qingquan Lei

doi:10.3390/polym11071134

Yanhui Wei, Guochang Li + Show 4 more

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https://doi.org/10.3390/polym11071134

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Abstract

Semi-conductive composites composed of carbon black-polymer play an important role in uniform electric field in high voltage direct current (HVDC) cable. They also affect space charge behaviors in the insulation material. However, the charge injection characteristics of semi-conductive composites are not detailed. In this work, the electrode structure of ‘Semi-conductive composites- Insulation material- Metal bottom’ (S-I-M) is proposed, and the currents formed by injected charges from semi-conductive composites are characterized by the thermally stimulated depolarization current (TSDC) method. Further, the experimental results based on the structure of S-I-M are compared with the traditional electrode structure of M-I-M (Metal upper electrode- Insulation material- Metal bottom electrode) and the simplified cable electrode structure of MS-I-M (Metal upper electrode-Semi-conductive electrode- Insulation material- Metal bottom electrode), respectively. The experimental results show that the semi-conductive composite plays an important role in the charge injection process and it presents a different tendency under different compound modes of temperature and electric field. For the low electric field (E ≤ 5 kV/mm) and the low temperature (T ≤ 50 °C), the current caused by the accumulated charges follows the rule, IS > IMS > IM. For the low electric field and high temperature (T > 50 °C), the current caused by the injected charges follows the rule, IMS > IM > IS. This phenomenon is closely related to the interface characterization and contact barrier.

Highlights

The semi-conductive layer is an essential component of high voltage direct current (HVDC) cables and plays an important role in the uniform electric field and makes the conductor wire core and the insulation layer connect tightly [1,2,3,4,5,6,7]
The conclusions are drawn as follows: (1) For the low electric field (E ≤ 5 kV/mm) and the low temperature (T ≤ 50 ◦ C), the current caused by the injected charges follows the rule, IS > IMS > IM
For semi-conductive composites, the charges can be injected to the insulation material because of countless tiny conducting spheres, which can cause the interface electric field distortion between semi-conductive composites and the insulation material, resulting in the lower interface barrier

Summary

Introduction

The semi-conductive layer is an essential component of high voltage direct current (HVDC) cables and plays an important role in the uniform electric field and makes the conductor wire core and the insulation layer connect tightly [1,2,3,4,5,6,7]. Space charge accumulation in the insulation layer is one of the key factors that threaten the safe operation of the HVDC cable, which can cause local electric field distortion, resulting in the degradation or breakdown of the insulation material. The semi-conductive layer is located between the conductor wire core and the insulation layer. As the electron transport path from the conductor to the insulation material, it affects space charge accumulation in the insulation. It is important to thoroughly understand the charge injection characteristic of semi-conductive composites

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Conclusion