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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...
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...
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 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 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...
High voltage circuit breakers are most important protective device in power system. Dynamic contact resistance measurement (DRM) is considered to be an effective assessment technique for contact ablation which has been widely used for many years. However, the contact resistance curves will be influenced by many factors, such as injected current and velocity. In power systems, circuit breakers often...
The measurement and analysis of the spatial morphology and dynamic characteristics of the electric arc plasma inside low voltage circuit breaker is an effective way to improve its breaking performance and modern testing techniques have been applied to the experimental study on switching arc plasma in recent years. However, these techniques usually need to destroy the extinguishing chamber wall and...
The objective of this paper is to determine the dependence of field enhancement factor β on power frequency (50 Hz) voltage in vacuum. A rod-plane vacuum gap was designed in a vacuum interrupter. Shots of ac power frequency voltage were applied at three vacuum gaps till breakdown occurred and the three vacuum gaps were 1.0 mm, 0.8 mm and 0.5 mm, respectively. The field emission current and applied...
With the intelligentization of distribution network, a large scale of power electronic devices are applied in energy conversion. And the system flow of distribution network becomes random and varies greatly, which puts forward higher requirements for measurement and protection. Therefore, it's necessary to detect and identify short-circuit fault rapidly and effectively. In this paper, an early detecting...
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