275 KV Self-Contained Oil-Filled Cable Insulated with Polymethylpentene Laminated Paper

This paper described the newly developed insulating paper, which has very low dielectric loss and high dielectric strength, and electrical and mechanical properties of the cable with this paper. The insulating paper, which is called PML, consists of one layer of polymethylpentene and two layers of cellulose paper laminated. PML has several features such as not only low dielectric loss of 2.8x 0.001 as e * tan 6 and high dielectric strength but also poor swelling and excellent heat resistance. The PML was even swelled and increased several per cent of its thickness after immersing in oil with 100 °C for 24 hours. To cope with the swelling of the paper, we had to adopt a new manufacturing technique to produce a self-contained 275 kV and 500 kV oil-filled cable. Tests were carried out on a 275 kV PML insulated OF cable, and we obtained the test results as follows: .tan s was 2.76 x 0.00076, A. C. breakdown stress was 54 kV/mm and impulse breakdown stress was 149 kV/mm. The testresults proved that 275kV OF cable could be satisfactory used in service.