Fan Xingming

Dielectric strength and statistical property of single and triple-break vacuum interrupters in series

The maximum possible improvement factor of vacuum circuit breaker (VCB) with multiple breaks compared with one-break, which had the same total gap length, was deduced. Based on the research on the breakdown weak points in high voltage vacuum gaps, a theoretic model was set up for describing the statistical property of multi-break VCB. Dielectric experiments were carried out on a commercial vacuum interrupter arrangements with single break or triple breaks in series under lightning impulse voltage. It shows that the more numbers in series are, the higher the breakdown voltage improvement factor is. The statistical results show that the triple-break vacuum interrupters in series have lower breakdown probability compared with a single-break one. It can be demonstrated in a preliminary study that the experimental results confirm the previous theoretical studies.

Dielectric Strength and Statistical Property of Single and Triple-Break Vacuum Interrupters in Series

The maximum possible improvement factor of VCB with double or multiple breaks compared with one-break, which have the same equivalent gap length, is deduced. Simultaneously, from the research on the breakdown weak points in high voltage vacuum gaps, their turn out and distribution, a theoretic model was set up for describing the statistical property of multi-breaks VCBs. This paper describes dielectric experiments on the commercial vacuum interrupter arrangements with single break or triple breaks in series. The experiments were carried out under lightning impulse voltage (LIV). It shows that the more numbers in series are, the higher the breakdown voltage improvement factor is. The statistical results show that the triple-break vacuum interrupters in series have the lower breakdown probability compared with the single-break one. It can be demonstrated in a preliminary study that the experimental results do confirm with the previous theoretical studies

Verification of a Fast Making Switch Based on Triggered Vacuum Switch and Vacuum Circuit Breaker

During synthetic making test a high speed making device is necessary to connect the switching device under test immediately after pre-strike during closing operation under applied voltage. A new kind of fast making device is emphatically expounded in this research, which is composed of triggered vacuum switch (TVS) and a fast vacuum circuit breaker (FVCB) with permanent magnetic actuator. Parallel-connected TVS and FVCB make up the basic optic-controlled module. And basic modules arranging in series can be increase the hold-off (withstand) voltage. When the closing command is triggered, TVS acts in several microseconds and carries the high making current first FVCB acts as the parallel protecting device for TVS, its closing command is sent simultaneously with TVS. Once FVCB closed the making current will shift to this branch, the erosion in TVS can be remarkably decreased. In this paper, a theoretical analysis is made and typical result is simulated with the power system simulation software EMTDC/PSCAD. The simulation result is similar to the experiment one. From the experiment and theoretical result it is known that the new kind of fast making device is feasible for synthetic making test of high voltage circuit breakers

A fast making switch based on triggered vacuum switch and fast vacuum circuit breaker

The key to perform synthetic making test at full rated voltage for high voltage switches is the making device of current source, which should have the capability to withstand the static and transient voltage and also can conduct short-circuit current without excessive erosion, Moreover it ought to be hair-trigger and control accurately. A new kind of fast making device is emphatically expounded in this research, which is composed of triggered vacuum switch (TVS) and a fast vacuum circuit breaker (FVCB) with permanent magnetic actuator. Parallel-connected TVS and FVCB make up the basic optic-controlled module. And basic modules arranging in series can be increase the hold-off (withstand) voltage. When the closing command is triggered, TVS acts in several microseconds and carries the high making current first. FVCB acts as the parallel protecting device for TVS, its closing command is sent simultaneously with TVS. Once FVCB closed the making current will shift to this branch, the erosion in TVS can be remarkably decreased. The chief aim of this research is to investigate the feature of TVS and FVCB, and to determine experimentally whether the provided fast making switch was suitable for high voltage circuit breakers synthetic making test. In order to research and optimize the triggering performance of TVS and actuator of FVCB, lots of simulation and experiment have been carried out and the results are also provided in this research.

Experimental investigations on the triggering characteristic of triggered vacuum switch under DC and AC load

Triggered vacuum switches (TVS), have found fast growing applications in the field of power system and pulse power. The relation between triggering parameter of triggering system, such as triggering voltage and triggering power, between the trigger time delay and it s scatter of triggered vacuum switch (TVS) had been obtained through series of experiment. The result can be adopted as the steering for high-powered controller design and application of TVS. A steepened high-voltage trigger pulse is introduced in the main high-voltage generating circuit. As a result the trigger time delay and it s scatter can be decreased remarkably. Synchronous switch technology is imported to control the triggering phase at the crest of applied voltage on TVS. The Triggering Characteristic of TVS under AC and DC load has been investigated emphatically. Given the identical triggering parameter of triggering system, the DC condition is prior to AC on the triggering probability and stability markedly. Such the conclusion can be drawn, for AC condition TVS would require much for the triggering system.

Application research on the full-voltage synthetic making test system for high voltage switches

Compared with high power laboratories abroad, high voltage test level in China is to be improved. In order to meet the development requirements of modern circuit breakers and to better simulate the network, testing capabilities have to be expanded. According to the existing equipment and testing conditions of main domestic test house, a new testing circuit for synthetic making test of high voltage circuit breakers is proposed. During synthetic making test a high speed launching device is necessary, which connect the switchgear under test to current source immediately after pre-strike during closing operation. A new kind of fast making device is emphatically expounded in this research, which is composed of triggered vacuum switch (TVS) and fast vacuum circuit breaker (FVCB) with permanent magnetic actuator. Based on the synchronous closing technology, controlling strategy and its realization of synthetic making test system are fulfilled, which adopt pre-arcing current in the switch under test and the phase difference between applied voltage and making current in the range of 90plusmn27deg as the criterion for whether the launching device to act. Therefore the validity and successful rate of synthetic making test can be guaranteed. Finally, the prototype of the proposed launching device of current source at rated parameter 110 kV/63 kA and the measurement and control system for synthetic making test are fulfilled in our research. And the functional and reliability test has been carried out at Xipsilaan High Voltage Apparatus Research Institute of China.

The assessment and prediction method for VCB contact endurance research based on LM-BP neural network

The LM-BP neural network prediction model for contact system electrical endurance of vacuum circuit-breakers is established, which based on the electrical endurance curve and the advanced breaking current weighted cumulative method (BCWC). The influencing factors that affect the prediction of VCBs electrical wear were researched. Then the LM-BP algorithm iterative process of contact electrical wear is significantly analyzed, and the detailed process of establishing the LM-BP electrical endurance model is presented also. Furthermore, the technique and the cautions of selecting hidden layer neurons and confirming of hidden layer node number during the process of establishing the LM-BP model are specially analyzed. At last, the neural network training and prediction has been carried out based on the obtained samples. The relative error of desired output and actual output is analyzed and the corresponding results are presented also. The results show that the LM-BP neural network of VCBs contact system, discussed in the paper, can accurately predict the residual contact wear. And the method provided in the paper presents not only a new idea to the on-line condition monitoring of the electrical endurance of VCBs contact system, but also valuable for engineering application of on-line monitoring and forecasting.

VCB contact system electrical endurance on-line condition monitoring technology and its application

In order to reduce the number of accidents and prevent possible troubles due to the failures of VCBs, one valid way is to monitor their performance and condition on-line. Based on the understanding and development of condition based maintenance (CBM) of high-voltage circuit breakers, the authors give some general introduction to electrical endurance on-line condition monitor for VCBs, in which the stress put on the non-intrusive method and device for determination of the arcing duration. The principle and configuration for arcing duration detect are emphatically expounded in our research, in which the electromagnetic induction theory is adopted for the arcing initialization and duration detect. The simulation and experimental results of the arcing detect device are provided in detail. The accuracy and stability of the arcing detect device have been demonstrated and it can distinguish co-existing arc signals in three-phase of circuit breakers. In the end, an algorithm for the electrical endurance of vacuum circuit breakers on-line condition monitoring system is proposed, which based on TMS320F2812 one type of DSP281X series produced by Texas Instruments semiconductor. The universally accepted approach of accumulative breaking current of high voltage circuit breaker contact to diagnose electrical endurance is used in the High-voltage Circuit Breakers Electrical Endurance On-line Monitor system.

The least squares method for VCB electrical endurance parameters predicting research based on breaking current weighted cumulative method

Calculating method of the current index alpha and the theoretical total wear Q is emphatically analyzed based on the electrical endurance curve, which adopt advanced breaking current weighted cumulative method (BCWC) used for predicting the remaining electrical endurance of vacuum circuit breaker (VCBs) contact system. The purpose of this work is to provide a clear and concise engineering description for VCBs contact system on-line monitoring practically. The mathematical and theoretical model of electrical endurance for VCBs contact system is established. The current index alpha and the theoretical wear Q are analyzed in detail based on the method of least squares. Then the parameters predicting method used for prognosticating remaining electrical endurance is proposed. Comparative study was carried out, through which the validity and feasibility of researched method can be verified. The results of this work show that the achievement and the researched procedure are correct and reasonable, which indicate the total wear of a VCB contact system is certain once contact material and structure type is determined. Moreover, based on the method provided, the relation between breaking current and already operation time is also can be gained. So the current index alpha and the theoretical wear Q applying to the advanced breaking current weighted cumulative method are obtained. Finally, the hardware and software for VCB contact system electrical wear on-line monitoring device is fulfilled based on the research results mentioned above. This work can provide some reference for engineering application for electrical endurance on-line monitoring of VCBs contact system.