Cubicle Type Gas Insulated Switchgear Research Articles

Estimation method of degraded vacuum in vacuum interrupter based on partial discharge measurement

Loss of vacuum in vacuum interrupter (VI) is becoming an interesting theme for VI used in medium voltage range beyond its lifetime of typically 20-30 years. The early detection of abnormality in the vacuum insulated equipment is important not only for the operating vacuum circuit breakers (VCBs) in medium voltage but also for the development of higher voltage VCBs, such as cubicle type gas insulated switchgear (C-GIS) with compressed gas and/or insulation gas. The purpose of present study is to estimate the vacuum degree in VI by measuring partial discharges (PDs) occurring in medium vacuum range for more than 1 Pa. As a leakage gas, atmospheric air and SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas were sealed into the VI with close-state, whose pressure was regulated through vacuum pump systems, which corresponds to the left region of its PD inception voltage (PDIV) curve. From PD current waveforms measured by detecting resistor connected to plane electrode outside the VI, PD charges, occurrence frequency and phase characteristics of PDs for each applied AC voltage and internal vacuum pressure were determined. It was concluded that, by statistical processing using PD parameters and histogram, a number of occurrence of PD and PD charges would be dominant parameter for determination of the internal pressure of VI with the leakage gas of air.

Temperature Rise Simulation of Medium Voltage Cubicle Type Gas Insulated Switch-Gear Based on Coupling of Multi-Physical Fields

Usage of Cubicle type Gas-Insulator Switch-gear (C-GIS) is gradually increasing in power system. During the operation of C-GIS, long-term excessive temperature rise leads to degeneration of insulation and mechanical property, which may finally leads to fatal accidents. In order to analyze the temperature distribution of the C-GIS, the model of a 40.5 kV medium voltage SF 6 insulated C-GIS has been established and simulations based on electromagnetic-fluid-temperature coupling are carried out. In the simulations, eddy-current filed is solved by ansys-multiphysics to obtain the heat generation inside the C-GIS. In order to improve calculation accuracy, the contact resistance is taken into consideration and the physical characteristics of SF 6 gas are considered to be related to the temperature. First, simulations with and without surrounding air environment considered are carried out and the results are compared. The type test of temperature rise is also conducted to verify the simulation results. The simulation results are found out in agreement with experimental results. Second, in order to reduce the temperature rise and improve the design of C-GIS, recommendations are put forward. The influence of the cooling system and surrounding barriers is analyzed by numerical simulation.

The Development and Practical Use of A New 24 kV Dry Air Insulated Switchgear

We have developed a new environmentally fitted 24kV cubicle-type gas insulated switchgear (C-GIS) applying our dry air insulation technology and the electromagnetic actuation technology. Firstly, we clarified the relationship between the breakdown field strength at the tip/edge of high-voltage electrode in dry air and the field utilization factor expressing non-uniformity of the insulation gap. Based on the relationship, we designed the most suitable configuration and arrangement of the parts such as high-voltage conductors, disconnecting blades and some mechanical parts in a gas vessel. We succeeded in reducing both the number of insulation barriers and their size, compared with the former product. To reduce them, we produced some sample gaps simulated a practical insulation gap in the C-GIS and investigated its breakdown voltage dependence on the barrier height. Secondly, to apply the electromagnetic actuators for the operation mechanisms of the vacuum circuit breaker, we developed a new coupled analysis method that estimates the movement of a plunger inside the electromagnetic actuator and the electric current flowing through a closing/opening coil. Based on the analysis method, we could reduce both the number of the parts and close/open energy 45% and 80%, respectively, compared with the former spring-charged mechanism.

Insulation characteristics of vacuum interrupter for a new 72/84 kV C-GIS

This paper describes insulation technology for 72/84 kV vacuum interrupter for a new cubicle-type gas insulated switchgear (CGIS). The insulation performance has been increased significantly by a multi-gap shield configuration around the ceramic surface, which resulted in a 40% volume reduction of the vacuum interrupter. The CGIS housing the vacuum interrupter also reduced by 40% in volume. In the paper, the authors describe the basic characteristics on surface insulation and the area effect on surface insulation and their application to an new 72/84 kV CGIS.

キュービクル形ガス絶縁開閉装置の技術動向

キュービクル形ガス絶縁開閉装置の技術動向

66/77-kV C-GIS using composite insulation in SF6 gas

A second-generation model of cubicletype gas-insulated switchgear (C-GIS) with composite insulation incorporating SF6 gas has been developed. The design does not require a gas process in field assembly; it has high reliability and its installation is more rapid; and a further reduction in size is achieved. The design principles are described in detail.

Increase of breakdown voltage due to composite insulation in SF6 gas

AbstractThe breakdown characteristics using a hemispherical tip rod (10 ∼ 60 mm) molded with epoxy resin‐to‐plate gap in SF6 gas up to 0.20 MPa was studied.The result shows that breakdown characteristics are classified into three regions (A, B and C region) depending on gap length. In the A‐region breakdown voltage is lowered compared with bare hemispherical tip rod‐to‐plate gap. In the B‐region breakdown voltage is raised sharply with gap length and in the C‐region it saturates. The maximum increase ratio of breakdown voltage in the B and C region are 1.95 times (ac) and 1.68 times (impulse) compared with a bare hemispherical tip rod‐to‐plate gap characteristic.The ratios depend on the diameter of the spherical tip rod and the thickness of epoxy resin. It is concluded that the increase of breakdown voltage is attributed to the synergism effect of the decrease of maximum electric field strength by epoxy resin and the suppression of field emission.The use of composite insulation reduces the gap length drastically in the gas‐insulated switchgear, for instance, C‐GIS (Cubicle‐type Gas‐Insulated Switchgear).

SF&lt;sub&gt;6&lt;/sub&gt;ガス中複合絶縁における耐電圧向上の検討

The breakdown characteristics using a hemispherical tip rod (10 ∼ 60 mm) molded with epoxy resin-to-plate gap in SF6 gas up to 0.20 MPa was studied. The result shows that breakdown characteristics are classified into three regions (A, B and C region) depending on gap length. In the A-region breakdown voltage is lowered compared with bare hemispherical tip rod-to-plate gap. In the B-region breakdown voltage is raised sharply with gap length and in the C-region it saturates. The maximum increase ratio of breakdown voltage in the B and C region are 1.95 times (ac) and 1.68 times (impulse) compared with a bare hemispherical tip rod-to-plate gap characteristic. The ratios depend on the diameter of the spherical tip rod and the thickness of epoxy resin. It is concluded that the increase of breakdown voltage is attributed to the synergism effect of the decrease of maximum electric field strength by epoxy resin and the suppression of field emission. The use of composite insulation reduces the gap length drastically in the gas-insulated switchgear, for instance, C-GIS (Cubicle-type Gas-Insulated Switchgear).