01_Fen Zong_huwa_pd - I EEE Transactions on Dielectrics and...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
IEEE Transactions on Dielectrics and Electrical Insulation Vol. 8 No. 1, February 2001 91 Relation between Electroluminescence and Degradation in XLPE Fan Zong-huai, T. Takahashi, J. Suzuki and H. Miyata Fujikura Ltd., Tokyo, Japan S. lemura, T. ltoh and T. Nakiri The Kansai Electric Power Co., Inc. Hyogo-ken, Japan N. Shimizu Meijo University, Nagoya, Japan ABSTRACT In order to clarify the relationship between electroluminescence (EL) and degradation in cross- linked polyethylene (XLPE), the EL measurement was carried out using three kinds of samples, block samples with two different electrode systems, and film samples. The spectral measure- ments revealed that the uv component of is below the detectable level of - 0.1 c/s (count per second), in contrast to partial discharge (PI)) light from microvoids or the tiny electrical tree which includes a uv component of 2 2 cls. Secondly, aging tests using XLPE block samples with needle-plane electrodes revealed that electrical degradation can take place even when the applied voltage is below the detection voltage. The above experimental results suggest that is not the origin of electrical degradation, i.e. photodegradation by the uv component of EL is not the dominant mechanism of electrical degradation. 1 INTRODUCTION LECTRICAL treeing is responsible for the breakdown of power ca- E bles with polymeric insulation, such as low-density polyethylene (LDPE) and crosslinked polyethylene (XLPE). Electrical treeing has two distinct periods: the induction period corresponding to the initiation phase, and the propagation period during which PD takes place and the tree grows. Electroluminescence, with an optical emission intensity very weak in comparison with that of PD [l-31, occurs in the initiation phase. Consequently, can be considered as a prebreakdown warn- ing and provide a probe to investigate the mechanisms leading to the degradation of insulating materials [4,5]. Since the early 1960’~~ polymeric materials, such as LDPE and XLPE, have been used as electrical insulation in underground power cables. Many polymer-insulated cables in service approach or exceed their de- signed lifetime of 30 yr. In order to evaluate the operating reliability of these cables, and predict their residual lifetime, it is imperative to clarify the nature of aging [6]. For this reason, much research work has been devoted to elucidate the phenomenon. However, we are still far away from a complete understanding of the relation between EL and degradation. There are two different opinions concerning this matter. One is that the ultraviolet (UV) light included in causes the photodegradation of insulation materials [2,7-121. Namely, EL is the cause of electri- cal degradation and the voltage at which starts is the degradation threshold of insulating materials. The other is that electron impact is responsible for degradation and also for [4,13,14]. Here, EL is not the cause of electrical degradation. Recently, Kabir et al. [15] found that the lower the light inception voltage, the lower is the treeing resistance, and vice zIersu. We also obtained the same result [16]. Nevertheless,
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

01_Fen Zong_huwa_pd - I EEE Transactions on Dielectrics and...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online