Tokui Yonemura

Model Cable Tests for a 275 kV 3 kA HTS Power Cable

High-temperature superconducting (HTS) cables are considered the next generation transmission line because they are compact, lightweight, and demonstrate large capacity and low loss compared to conventional cables. In particular, since a coated conductor (YBCO wire) provides high critical current, high magnetic-field property, low AC loss, and low cost, it is expected to make the HTS cable more attractive than other superconducting wire. In Japan, 66/77 kV HTS cables have developed for about 20 years. We started developing 275 kV class HTS cables three years ago based on 66/77 kV HTS cables. The goal is a 275 kV 3 kA cable with a capacity of 1.5 GVA, the same capacity as a typical overhead transmission line, which serves as the backbone of Japanese power networks. The following technical developments will be carried out: high current and low AC loss cable conductors and high voltage insulation and low dielectric loss cables. Regarding high current and low AC loss cable conductors, 3-kA cables have been fabricated, and AC losses have been measured. We found that using thin YBCO wire reduced AC losses in experiments.

Artificial contamination tests of silicone rubber cylindrical models

To develop the composite insulator termination for EHV XLPE Cable, especially for those used for contamination conditions, it is necessary to evaluate the contamination performance of composite insulators. This article presents the results of artificial contamination test on the cylindrical model made of FRP tube covered with silicone rubber, and also introduces the relation between methods of making contamination samples and the equivalent salt deposit density (ESDD) levels on the surface of the samples. Comparing with salt (NaCl), a mixture of several contamination deposits was also used to evaluate the contamination performance of the samples. Artificial contamination tests were performed in a clean fog room. Several contaminated silicone rubber cylindrical samples with different diameters were tested. AC flashover voltage was measured by changing the ESDD level.