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The objective of this paper is to propose a dc current interruption technology for railway dc traction systems, consisting of a dc vacuum circuit breaker with a superconducting fault-current limiter (SFCL). To this end, a 1.5-kV dc circuit breaker prototype is designed, involving a dc vacuum circuit breaker and a resistive-type SFCL serially connected. The dc vacuum circuit breaker is developed with...
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...
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 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...
Using a M-effect metal is an efficient method to shorten the pre-arc time of current-limitinging fuse. But the M-effect can't work on high current range. the arrangment of M-effect metal have a significantly influence on the pre-arcing time of current-limiting fuse. The objective of this paper is to determine the influence of the arrangment of M-effect metal on the overload current pre-arcing time...
This paper presents a work that was aimed to study the arc motion characteristics of low-voltage circuit breaker based on the magnetic testing technology by using hall sensors to obtain the data about the magnetic field distribution. Combined with the images of arc movement obtained by the CCD camera, the relation between magnetic field distribution and the arc motion during the interruption process...
The speed characteristic of moving contact is vital to the high voltage circuit breakers. But due to the contacts of high voltage circuit breaker are completely isolated by arc chamber, the common measurement methods have some disadvantages. In this paper, a new method for measuring the speed characteristics based on machine vision algorithm is developed. This noninvasive method just needs to draw...
The objective of this paper is to improve the fatigue life of a contact spring pin in a 126 kV vacuum circuit breaker (VCB). Firstly, the fatigue life of the contact spring pin during the opening or closing operation of the 126kV VCB is analyzed. Secondly, an orthogonal experimental method is used for the improvement of the fatigue life of the contact spring pin, in which three impact factors are...
In order to replace the SF6 gas with strong greenhouse effect in the high-voltage switchgear, CO2 has become one of the hotspots. In this paper, LW35-40.5(G)/T2500(3150)-31.5 gas-blast circuit-breaker is used as the research object to study the dielectric recovery characteristics of CO2 gas-blast arc chamber under no-load breaking, so that the theoretical basis for the development of CO2 circuit-breaker...
SF6 is a potent greenhouse gas and one of the promising alternatives is CO2. So this paper took CO2 rotating arc chamber as research object. The influence of the breaking angle and the magnetic field on the chamber was analyzed theoretically. Ansoft Maxwell software was used to simulate the magnetic field distribution in order to analyze the influence of the factors. Those factors are the number of...
In vacuum interrupters, anode spot formation is commonly known as a high-current anode discharge mode and it significantly decreases the current interruption capacity of the vacuum interrupters. To understand the mechanism of the anode spot formation, the heat flux density delivered to the anode is of vital importance. The objective of this paper is to determine the peak heat flux density at a transition...
During the making operations for the back-to-back capacitor banks switching, the inrush current arcs can locally melt the contact surfaces of vacuum interrupters (VIs) in prestrike processes. The condition of the contact surface can significantly influences the behaviors of the inrush current prestrike arcs. The objective of this paper is to determine the influence of contact plate slots on inrush...
Insulating liquid, because of high breakdown strength and superior self-recovery property, is widely applied to intense electron beam accelerator, transformer, and superconducting fault current limiters, etc. However, the formation of bubbles caused by heat transfer in power equipment seriously hurts the performance of the insulating strength in liquid. The objective of this paper is to study the...
Hybrid DC circuit breakers have the advantages of fast fault current interruption with the solid-state semiconductor devices and low conducting loss with the mechanical switches. Therefore it is suitable to be used in the multi-terminal DC transmission system. The objective of this paper is to determine a voltage sharing between the mechanical switch and the IGBTs in a proposed topology of hybrid...
The Objective of this paper is to explore the possible decomposition pathways and products of Perfluoronitrile C4F7N by density functional theory (DFT). First, the molecular structure, vibrational frequency and energy information of C4F7N and other major molecules are calculated by Materials Studio software. These results of some species(CF3, CF2, CF, C2F4, C2F5 and so on) are in a good agreement...
The objective of this paper is to determine minimum arcing interruption performance of a 126 kV single-break vacuum circuit breaker with 3/4 coil-type axial magnetic field (AMF) contacts. The full contact gap was 50 mm. A spring type mechanism was used to provide an average opening velocity of 3.0 m/s within 20 mm after contacts separation. Test duty T100s experiment with a rated short circuit current...
The controlled switching technology of a short circuit current has been proposed for a long time. However, the opening time of the mechanism used in the high voltage circuit breaker is normally tens of milliseconds and has a variation of milliseconds. The electromagnetic repulsion mechanism has a very limited variation in the opening time. It provides a potential of achieving the controlled switching...
The insulation capability is a key indicator for designing a vacuum interrupter. A vacuum discharging process, especially the initial stage of it, is correlated to the capability. However, the effect of anode is still uncertain in a vacuum discharge process. The objective of this paper is to experimentally investigate the effect of anode on the initial stage of a vacuum discharge. A ICCD camera was...
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