Masayuki Tan

New partial discharge detection method for live UHV/EHV cable joints

Partial discharge (PD) detection for live UHV/EHV power cables and accessories is the most important test on cable systems, to prevent problems caused by minor mistakes in jointing the cable. A new PD detecting method is proposed. A REDI (resonance type partial discharge) sensor was developed for detecting PD occurring inside the joints of live XLPE insulated cables. This sensor picks up the high frequency components of a PD pulse in the noiseless range (for example, for 10 to 50 MHz). This new method was employed to observe the initial AC breakdown tests applied to three different types of joints used in UHV/EHV power cables. PD pulse sequences were observed just before the breakdown in all cases. A PD pulse sequence against the phase of applied voltage (A gamma -q characteristic) changed with time or degree of deterioration of the sample. Results of these experiments show that a REDI sensor can be used for insulation diagnosis of live power cable joints. >

Development of 500-kV XLPE cables and accessories for long distance underground transmission lines-Part II: jointing techniques

This paper reports on the results of a basic inquiry for the purpose of developing extrusion-molded joints (EMJ) for use with 500 kV XLPE power cable. The authors have made it clear that the factors that govern EMJ performance, like cable performance, are contaminants in the insulation and protrusions in the semiconductor layer. Through modeling experiments, the authors determine the minimum breakdown strength of EMJ and use this to determine design values for 500 kV EMJ. Finally, they carry out breakdown tests on actual equipment, resulting in the prospect of the actual realization of 500 kV EMJ. >

Development of 500-kV XLPE cables and accessories for long-distance underground transmission lines. IV. Electrical properties of 500-kV extrusion molded joints

Joints for 500-kV XLPE cable are now under development in Japan to enable the long-distance transmission of high-capacity power to urban areas. Basic research was carried out from 1989 to 1992 that determined joint type and design values. This paper reports on the electric performance of the fabricated joints. Various tests were conducted to evaluate the performance and the design values. As a result of this evaluation it was found that it was possible to realize joints for 500-kV XLPE cable. Field tests are conducted as the final stage to confirm the long-term performance of the system.

New partial discharge detection method for live power cable systems

A novel partial discharge detector, the REDI (resonance-type high-frequency partial discharge) sensor, is developed for picking up the high-frequency components of partial discharge (PD) current pulses from live cable systems. This sensor was applied to initial AC breakdown tests of practical joints of XLPE (cross-linked polyethylene) insulated cables, and PD could be clearly observed in all cases (the minimum apparent charge was 5 pC with 275 kV cables). The phase characteristics of PD against the applied voltage changed just before the breakdown.<<ETX>>