01_bamji_HV_highvacuum - I EEE Transactions on Dielectrics...

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 glectrical Insulation Vol. 8 No. 2, April 2001 233 Light Emission in XLPE Subjected to HV in High Vacuum and Pressurized Gas S. S. Bamji, A. T. Bulinski and I. Powell National Research Council of Canada Ottawa, Ontario, Canada and N. Shimizu Meijo University Nagoya, Japan ABSTRACT The spectral and spatial resolution of electroluminescence, the light emitted from polymeric insulation subjected to high electric field, is studied in a test cell pressurized to 215 kPa with ultra high purity nitrogen gas. The paper also describes light emission from crosslinked poly- ethylene (XLPE) subjected to HV in an ultra high vacuum test cell. It is shown that the charac- teristics of light emitted from XLPE in the evacuated test cell are quite different from the light emitted when the test cell is pressurized. The mechanisms responsible for light emission un- der high vacuum condition are described and it is suggested that care should be taken when interpreting the light detected from polymeric insulation subjected to high electric fields. 1 INTRODUCTION LECTROLUMINESCENCE (EL), the emission of light due to high elec- E tric fields, has been observed in insulating materials such as poly- ethylene, polypropylene and epoxy resin. The EL technique has been employed successfully in the initial development of the 500 kV under- ground cables. Although a sophisticated setup is required to detect the faint light, the technique is sensitive enough to reveal the very early stages of insulation degradation, prior to partial discharge and electrical tree inception. The advantages of the technique are that 1. it can detect the onset of the deterioration processes, even before the first partial discharge occurs in the insulation. Since degradation initi- ates only in a small volume at the point of electric stress enhancement in the material, the degraded region can be analyzed further with other techniques, and compared with the adjacent non-degraded regions. 2. it can determine the effect of time-dependent mechanisms such as space charge injection, trapping and decay in insulation subjected to ac [l-31, dc [4], and impulse voltages [5]. Faraday Cage 3D OPTICAL TABLE 23m 4 ... . . .. Figure 1. Experimental setup. 3. it can be employed to evaluate additives used in the polymeric insula- tion of distribution and transmission class underground cables [l]. 4. it is the only technique that can detect the conversion of a water tree to an electrical tree [6]. 5. it is several orders of magnitude more sensitive than the conventional partial discharge detection method [7]. voltage below the EL inception level does not develop electrical trees; while the insulation held above that level always does [7]. Also, the inception voltage gives an indication of charge injection and space charge formation in the polymer.
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.

This note was uploaded on 06/11/2011 for the course ELECTRICAL 124 taught by Professor Ghjk during the Spring '11 term at Institute of Technology.

Page1 / 6

01_bamji_HV_highvacuum - I EEE Transactions on Dielectrics...

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