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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...
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...
The objective of this paper is to compare mounted angles between a pair of 2/3 coil-type AMF electrodes in a 126 kV single-break vacuum interrupter. Three kinds of mounted angles are assigned, which include 0°, 30°, and 60° slot shift between a pair of contact plates. A comparison of the mounted angles is made from the point of view of the distribution of axial magnetic flux density, the AC and DC...
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...
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...
Nowadays the phase controlled switching is a preferred method for capacitive switching. Thus the distribution of prestrike gaps is an important issue for the control strategy. The objective of this paper is to understand the distribution of prestrike gaps for the contact materials manufactured by arc-melted and infiltration preparing technology in the capacitive service condition of 40.5kV vacuum...
Predicting zeroes precisely and rapidly after a fault initiation is the basis of controlled fault interruption. However, none available algorithms could predict current zeroes within several milliseconds. The objective of this paper is to propose a fast estimation algorithm that can predict current zeros within 3ms after fault initiation. An algorithm is proposed based on an improved BP network. In...
There are few investigations of DC self-excited oscillation interruption under transverse magnetic field (TMF). The objective of this paper is to understand the effects of transverse magnetic field on DC interruption characteristics of CO2 and SF6 gases based on the self-excited oscillation principle. The DC self-excited oscillation interrupting characteristics of CO2 and SF6 at 0.5 Mpa absolute atmospheric...
The objective of this paper is to determinate the influence of grading capacitance on breakdown characteristics of a double-break vacuum interrupter. A prototype of double-break vacuum interrupter was built up as a U-type configuration with two 12 kV vacuum interrupters in series. The double-break vacuum interrupter is stressed by a power frequency withstand voltage and a lightning impulse withstand...
The objective of this paper is to propose a quenching recovery time measurement method for superconducting fault current limiter used in DC circuit. The proposed measurement method includes an experiment circuit, in which there is a L-C discharging current source and a DC circuit breaker. The L-C current source can produce a high DC current which quenches the superconducting coil. Then the DC circuit...
DC resistive type superconducting fault current limiters (SFCL) can be used in multi-terminal DC systems for fault current limiting. They help DC circuit breakers interrupt fault current with lower interruption overvoltage and they improve the interruption reliability. Insulation design is necessary for the application of SFCLs. The objective of this paper is to design the insulation of DC resistive...
The objective of this paper is to optimize a 3/4 coil-type axial magnetic field (AMF) contact design used for 126 kV vacuum interrupter. Through central composite design and finite element calculation, axial magnetic field characteristics and loop resistance of the contact system with various design parameters were obtained. Four contact parameters including coil width w, coil height h, air gap width...
Researches on electromagnetic repulsion mechanisms are drawing more and more attention globally. The objective of this paper is to develop an electromagnetic repulsion mechanism for a 40.5 kV vacuum circuit breaker and then to make an optimization. Design of experiments (DOE) method are used to screen the prominent factors. Result shows that three impact factors are the prominent factors, which include...
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