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In recent type tests, a 252kV SF6 self-blast circuit breaker re-ignites several times after interruption. In order to solve this problem, through CFD simulation of the gas flow field in the interrupter on load, the pressure, temperature and velocity after current zero are analyzed carefully. The conclusion is that, due to the upstream pressure decreased quickly after current zero and will lower than...
SF6 has been widely used as insulating and arc-extinguishing medium in power equipment. Under discharges, lower fluorides of sulfur generated by the dissociations of SF6 will react with unavoidable moisture and oxygen to form corrosive byproducts (etc., SOF2, SO2F2, SOF4). These byproducts will reduce the insulating and arc-quenching capacity of SF6 power equipment, so it is necessary to study their...
Recently, the self-blast principle of extinguishing the arc by the blast pressure which is generated by the arc itself has been widely applied to the high voltage circuit breaker. In the self-blast principle, the pressure relief valve fitted on the piston is opened to release excessive pressure in the compression volume during high current interruption. The design of the pressure relief valve operation...
As a new actuator driven by Ampere force, Electro Magnetic Force driving Actuator (EMFA) is applicable to medium-high-voltage system with powerful output force, long stoke, simple structure and high reliability. In the paper, a new type of EMFA for 126kV VCB with single break is proposed on the basis of the mature manufacturing technology of 126kV vacuum interrupter. The model of EMFA is established...
A design gauge pressure of an eco-friendly gas insulated switchgear (GIS) with an application of vacuum interrupters (VIs) ranges from 0.1 to 0.3MPa. Therefore, a high differential pressure is imposed on bellows of the VIs, which increases the fatigue failure risk of the bellows after cycles of operations. Although, there are some empirical equations recommended by the Chinese National Standard GB/T...
This paper focused on a fast mechanical switch applied in 2kV hybrid DC contactor. An integrated design of vacuum switch based on Permanent Magnetic Actuator (PMA) is proposed. The stainless steel bellows is removed to avoid vacuum failure caused by air leakage and eliminate restriction of bellows' fatigue life compared to conventional vacuum switch. Both monostable structure and compact springs'...
DC transmission has a lot of merits compared with AC transmission. For example, the cost of the construction and the equipment is less than that of the AC transmission system. Besides, more energy can be transmitted in DC transmission lines. Recently, multi-terminal transmission lines are required urgently. For that purpose, the reliable DC transmission circuit breakers must be developed. As we all...
First peak non-limiting type FCL can be utilized for various purposes especially when fault occurs on the load at the outgoing feeder. One of them is to use for preventing spread of voltage sag until the circuit breaker operation. Another is to use for minimizing the blackout area through the protection coordination between main circuit breaker at feeder and the multi-circuit breaker in series at...
A prestrike high frequency inrush current arc will cause a local contact surface melting and welding in capacitive making process of vacuum interrupters (VIs). The contact surfaces may be damaged from a rupture of the contact welding during the next breaking operation, which has a negative effect on restrike. A fractal characteristic can be used to describe such irregular ruptures. The objective of...
The paper looks briefly at the development of vacuum interrupters to date, discusses limitations to the existing technology of Vacuum Switchgear, what these are, and also how these may be overcome. It then moves on to discuss new developments in Vacuum Interrupter/ Vacuum Circuit Breaker technology which are likely to have an impact on the next generation of devices. Finally, it looks forward ten...
In order to improve the intelligent operation level of the motor operation mechanism of 126kV vacuum circuit breaker, A control method of PWM rectifier real-time adjusting drive motor speed is proposed. The equations of motion of Brushless DC motor are given, the speed response characteristic of motor is analyzed, and the controllability of motor is studied. The working principle of PWM rectifier...
Vacuum circuit breakers are widely adopted in middle voltage class. Their application area has continued to spread to higher voltage class. Therefore the importance of electrical insulation technique in vacuum, especially the insulation of electrode gap has been required significantly. This paper describes the research on vacuum breakdown and discharges related to the electrode gap of vacuum interrupter.
The metallic vapor density in vacuum arc in a vacuum interrupter is crucial for deeper understanding of the anodic activities and dielectric recovery process. In this work, the objective is to measure the Cr metallic vapor density and its axial distribution along the gap in the vacuum arc between chromium contacts. The method of the optical absorption spectroscopy (OAS) using a broadband light source...
Based on the reflection and refraction of traveling waves and vacuum circuit breaker(VCB) characteristics, transformers interruption by VCB may produce current chopping and re-ignition that will cause severe high-frequency transient overvoltages in collection grid of offshore wind farms(OWFs). In such applications, overvoltages protection should be used. In order to study such overvoltage in OWFs,...
This paper aims at reliability assessment of power semiconductor in hybrid DC switch. Design considerations of reliability issues are explained. Specific focus is given to a temperature-based condition monitoring technique via thermo-sensitive electrical parameters. VCE, td(off), and dVCE/dt of IGBT are presented as the indicator of junction temperature and calibrated. Comparative experiments with...
As a key component of DC medium voltage breaker, the switch mechanism is required to open in high-speed and can withstand the breaking voltage which is generated during opening motion. Thus, the design of driving circuit of switch mechanism is very important to optimize the mechanism structure and improve mechanism opening characteristics. First the motion principle of high-speed switch was given...
Based on theoretical analysis and experimental research short-circuit electromagnetic forces of three-phase medium voltage (MV) earthing switches (ES) with different motion forms and different structural arrangements of ground loop have been studied. And the influence of electromagnetic force under correspondent various conditions on short-circuit making performance is discussed in detail as well...
Considering the factors of skin effect, contact resistance, natural convection and radiation, etc., Multi-physics field coupling simulation model for 3D electromagnetic, flow and temperature field of AC high voltage GIS busbar is established, power loss, temperature and gas flow distribution is calculated and analyzed, the distribution of the temperature gradient is obtained; Based on the proposed...
A coupled fluid-mechanical dynamics analysis method is presented in this paper. A commercial simulation package is used for mechanical dynamics calculation, which employs user-developed dynamic-link library files as routine interface to enable data exchange with gas pressure calculation. This part is responsible for the calculation of mechanical motion, including the tripping of trip trigger, releasing...
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