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In this paper, the insulating void defect inside the insulating spacer of onsite 252kV GIS is analyzed by ultra-high frequency (UHF) partial discharge (PD) diagnosed method and industry CT apparatus. The defect position of onsite GIS is located by using the time difference of arrival (TDOA) method of UHF signal. The pulse current method and UHF method is combined together to investigate the variation...
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...
This paper presents the experimental results on electromagnetic behavior of galinstan in liquid metal current limiter in case of rated and short circuit current respectively. For the former, the liquid keeps unstable in the channel like ‘boiling’ when DC current of 1kA passes it and pinches to ignite the arc finally within the channel in several minutes, which is observed by a specially designed test...
Uncontrolled energization of unloaded transformers is usually associated with a large inrush current, several times larger than the rated transformer current. This transient can cause unfavourable consequences including reduction of transformer lifecycle, protective relay misoperations, and reduced power quality of the system. Controlled switching can efficiently eliminate these transients when energizing...
A new controlled fault current limiting (CFL) technology based on series vacuum switch was proposed to decrease the overvoltage and arc energy in current converting process. Compared with the directly fault current limiting (DFL), the response time of the CFL limiter, which is based on an optimum fault current zero-crossing prediction algorithm, was defined and analyzed. The arcing time, arcing current...
We carried out the study about temperature rise in Low Voltage switchgear on cooling systems. Ratings of this LV switchgear are 690 V, 4000 A, 85 kA and IP43. We compared the results with air cooling fan for forced cooling system and without the fan for natural convection system by numerical and experimental methods. As a result, we can obtain a calibration factor about the cooling systems on our...
With the development of 500 kV power system, the fault current capacity has been increased rapidly. A 500 kV fault current limiter model was founded based on fault current capture technology and vacuum switch technology. The fault current limiter had two operation modes. One was named FFCL (Forced zero-crossing Fault Current Limiter) in which the current was directly converted to the limiting reactor...
In order to improve the breaking performance of the ultra-high voltage SF6 circuit breaker, an optimal design scheme for increasing the straight line length of the nozzle throat is proposed. Based on the numerical simulation of the gas flow field in the optimized structure of the interrupter, the influence of the straight line length of the nozzle throat on the breaking performance of the circuit...
In this paper, dielectric recovery characteristic during operation of high voltage SF6 circuit breaker is studied by test method. The test circuit of dynamic breakdown characteristics is built. Circuit breaker closing and opening dynamic breakdown voltage curves under positive and negative polarity are obtained. Impact of inflatable pressure and closing speed to dielectric recovery characteristic...
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...
The paper investigates the pulsed AMF arc control on the vacuum arc and the post arc characteristic to reveal the mechanism of AMF arc control in different control time and find the proper AMF arc control. The pulsed AMF control system is designed and the pulse width is adjusting from 1.5ms to 10ms. The test circuit is set up in the synthetic test and the test VI is transparency in order to observe...
Post-arc current significantly influences the interrupting process of breakers, which can reflect the appearance of the arc before current zero and the residual metal vapors in electrode distance after current zero. In order to investigate the characteristics of post-arc current in DC interruption, a high speed hybrid actuator was designed, and forced current zero method was used to carry out the...
Basin-type insulators are major insulating components in GIS (Gas Insulated Switchgear), and have significant influence on the performance and reliability of the equipment. The basin-type insulators are mainly manufactured through epoxy resin vacuum-casting process. As “ceramic-like” materials, epoxy resin would bring internal stress during the curing process. The failure mechanism of this kind of...
Circuit breakers are important equipment to control the energy distribution and fault isolation in power grid. With the development of the power grid in China, the evaluation of health status of circuit breaker in operation becomes an important part of the operation management. A number of studies have been made on the evaluation of circuit breaker health status, but are mostly limited to interpretation...
High voltage circuit-breakers switching shunt reactor is ascribed to small inductive current interruption. What's more, circuit-interaction between the breaker interrupter and the surrounding circuit can result in transient voltage with high amplitude and high-frequency, which is a great threat to the power grid. Particularly, the re-ignition overvoltage of Ultra-High voltage circuit-breaker will...
DC voltage measurement device is the key equipment in the DC transmission system, which is mainly used for system voltage measurement and providing voltage signals to the measuring instruments and secondary protection devices. With the rapid development of DC transmission and flexible transmission in China, DC voltage measurement device has been widely used and developed. High accuracy and high stability...
In order to meet the trend of miniaturization, large capacity and intelligence of the current vacuum circuit breaker, a new model of three-phase disc rotation vacuum circuit breaker has been proposed, in which the main circuit distribution was changed from the same direction to the opposite. Besides, some adjustments were made to the position of operating mechanism. The electric field distribution...
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...
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