Impulse Breakdown Strength Research Articles

CVケーブルの直流,逆極性インパルス重畳電圧破壊特性

CVケーブルの直流,逆極性インパルス重畳電圧破壊特性

Electrical tests of short models of polyethylene tape dielectric for a superconducting ac cable

Electrical tests on short models of the dielectric for a lapped polyethylene insulated superconducting cable are described. Impulse breakdown strengths and 50 Hz discharge inception fields are reported. The impulse strengths were encouraging but the discharge inception fields showed that further development is required.

電力ケーブルの衝撃電圧破壊強度の長さ依存性の検討

電力ケーブルの衝撃電圧破壊強度の長さ依存性の検討

Dependence of impulse breakdown strength on cable length

Electrical Engineering in JapanVolume 93, Issue 3 p. 62-68 Article Dependence of impulse breakdown strength on cable length R. Kaneko, R. Kaneko Dainichi Nippon Cables, Ltd.Search for more papers by this authorK. Sugiyama, K. Sugiyama Members Dainichi Nippon Cables, Ltd.Search for more papers by this author R. Kaneko, R. Kaneko Dainichi Nippon Cables, Ltd.Search for more papers by this authorK. Sugiyama, K. Sugiyama Members Dainichi Nippon Cables, Ltd.Search for more papers by this author First published: 1973 https://doi.org/10.1002/eej.4390930309Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume93, Issue31973Pages 62-68 RelatedInformation

Development of Special Insulating Paper for EHV Power Cable

A special insulating paper, developed for use in EHV power cable, is described. Generally speaking, where the insulating paper is made of the same pulp, the thinner the paper, the higher the impulse breakdown strength, and the lower the power factor. In view of this fact, a special insulating paper (combination paper), with a high-impulse breakdown strength, low power factor, and great mechanical strength has been developed by making thin insulating paper and cementing a plurality of sheets together with a suitable adhesive. 275-kV, 1 ×1200 mm2 oil-filled cable and 275-kV, 3 ×1400 mm2 pipe-type oil-filled cable using this combination insulating paper have been proved to possess excellent properties, such as shown in Table IV and Fig. 10, respectively, and the special characteristics of the insulating paper are fully displayed in the finished cable. The motive for the development of the combination paper, its theoretical background, and the properties of the insulating paper and of the cable using that insulating paper are reported.

The breakdown of liquid dielectrics and its dependence on oxidation of the electrodes

The dependence of the impulse breakdown strength of a liquid dielectric on the natural oxide layer on the electrodes used for the test is considered. It is shown that an electric field may exist in the oxide layer owing to the chemisorption of oxygen, and that this would be expected to reduce the probability of electron emission from the cathode and thus increase the recorded breakdown strength. Results are given of experiments on the breakdown of pretreated transformer oil using stainless steel, brass, and aluminium electrodes which support this conclusion.

Insulation Phenomena of Compressed Air

Test data on impulse and 60-cycle voltage breakdown strength for compressed air with various electrode configurations are reported. The tests were made with rod-to-plane electrodes with spacings up to 8 inches and pressures to 250 psig (pounds per square inch gage). Breakdown phenomena of air insulation encountered in the development of an air insulated air-blast circuit breaker1 are reported. The methods used in locating, analyzing, and correcting the breakdown are discussed. The use of solid insulating material in conjunction with high-pressure air is discussed. Applications in barrier form, and as support members stressed in creepage, are covered briefly.

Dependence of the Dielectric Breakdown of Transformer Oil on Electrode Conditions

SEVERAL workers have found that the breakdown strength of an insulating liquid may be determined not only by its own composition and purity but also by the material and condition of the electrodes used to test it. Recent work in this laboratory is believed to show that the impulse breakdown strength of transformer oil is also dependent upon the thickness of the natural oxide layer on the surface of the electrodes.

The impulse breakdown strength of pyrex glass

Synopsis The electric strengt of Pyrex glass has been measured at temperatures between −50°C and +100°C, using approximately linearly rising impulse voltages of durations between 30 secs and 1 × 10−5 sec. The values of electric strength obtained from successive comparable measurements were within ± 2½% of each other, which is within the limits of the known random error. The high degree of reproducibility obtained in the present investigation is attributed to the technique used for cleaning the surface of the glass before applying electrodes. At the lowest temperature (−50°C) the electric strength was independent of impulse duration between 1 × 10−5 sec and 1.0 sec and amounted to 9.2 MV/cm. With the shortest impulse (1 × 10−5 sec) the electric strength was independent of temperature between −50°C and +100°C and its value was also 9.2 MV/cm. Above −50°C and with impulses of duration greater than 1 × 10−5 sec the electric strength was less than the above value and decreased with both increasing temperature and increasing impulse duration. The constant value of 9.2 MV/cm is very probably the intrinsic electirc strength of Pyrex glass. This value was not influenced by the choice of various electrode materials. The lower values obtained in the present investigation are attributed to space charge distortion of the electric field, caused by the accumulation of ions near to the electrodes. Since the ionic conductivity of Pyrex glass increases with rise in temperature, this effect may be expected to become more and more important as the temperature is raised, or as the impulse duration is increased.

High-pressure gas as a dielectric

Impulse and 60-cycle breakdown strength of sphere gaps, rod gaps, and of samples built up of solid and fluid dielectrics are reported. The tests were made in nitrogen up to 200 pounds per square inch gauge pressure and in Freon up to 70 pounds per square inch gauge pressure. Dielectric strength values were compared with the breakdown of transformer oil between the same electrodes. Gap conditions were found for which the 60 cycle breakdown was twice its impulse breakdown.

High-Pressure Gas as a Dielectric

Impulse and 60-cycle breakdown strength of sphere gaps, rod gaps, and of samples built up of solid and fluid dielectrics are reported. The tests were made in nitrogen up to 200 pounds per square inch gauge pressure and in Freon up to 70 pounds per square inch gauge pressure. Dielectric strength values were compared with the breakdown of transformer oil between the same electrodes. Gap conditions were found for which the 60 cycle breakdown was twice its impulse breakdown.