Dielectric characteristics of vacuum circuit breakers with CuCr and CuBi contacts before and after short-circuit breaking operations

Abstract This paper presents the results of the degree of irreversible changes of dielectric properties of vacuum circuit breakers with CuCr and CuBi contacts before and after short-circuit breaking operations. Tests of dielectric properties were performed on four different types of switching vacuum chamber with RMF electrodes in the form of a spiral disk with slots. The paper describes the configuration of measuring system for determining the dielectric properties of circuit breakers with DC, AC and pulse voltage. It also describes the measuring procedure. The results were analyzed and the experimentally obtained random variable breakdown voltage is found to belong to Weibull distribution in all cases. Based on these results it was found that for the vacuum circuit breakers with CuCr contacts and CuBi breakdown occurs by the emission mechanism after stopping of diffuse arc with the initial breakdown at the anode. It was also found that significant reduction of the breakdown voltage occurs only after a short-circuit current breaking for a constricted arc. Only in this case, the significant difference between circuit breakers with CuBi and CuCr contacts is observed. This difference is explained by the fact that breakdown voltage for a constricted arc strongly depends on the shape of the applied voltage by the action mechanism of micro particles generated during the breaking of the arc current for the vacuum circuit breakers with CuBi contacts and it is caused by material of contacts. The results confirm the lower degree of irreversible changes of dielectric properties of vacuum circuit breakers with CuCr contacts in operation.

[1]  Shanghe Liu,et al.  Measurements of body impedance for ESD , 1997, Proceedings Electrical Overstress/Electrostatic Discharge Symposium.

[2]  K. Stanković,et al.  Radiation effects in polycarbonate capacitors , 2009 .

[3]  K. Stanković,et al.  Simulated exposure of titanium dioxide memristors to ion beams , 2010 .

[4]  K. Stanković,et al.  Mechanism of electrical breakdown of gases for pressures from 10−9 to 1 bar and inter-electrode gaps from 0.1 to 0.5 mm , 2007 .

[5]  K. Stanković,et al.  Determination of Pulse Tolerable Voltage in Gas-Insulated Systems , 2008 .

[6]  P. Osmokrovic,et al.  Electrical breakdown mechanisms in vacuum diodes , 2010 .

[7]  P. Osmokrovic,et al.  Validity of the Space-Time Enlargement Law for vacuum breakdown , 2010 .

[8]  K. Stanković,et al.  Influence of tube volume on measurement uncertainty of GM counters , 2010 .

[9]  W. Whitney,et al.  Electron Emission Preceding Electrical Breakdown in Vacuum , 1963 .

[10]  G. Farrall,et al.  Polarity Effect in Vacuum Breakdown Electrode Conditioning , 1965 .

[11]  Wolfgang Hauschild,et al.  Statistical techniques for high-voltage engineering , 1992 .

[12]  P. Osmokrovic,et al.  Influence of switching on dielectric properties of vacuum interrupters , 1994 .

[13]  James M. Lafferty,et al.  Vacuum arcs : theory and application , 1980 .

[14]  K. Stanković,et al.  Reliability of semiconductor and gas-filled diodes for over-voltage protection exposed to ionizing radiation , 2009 .

[15]  G. Lins.  Evolution of Copper Vapor from the Cathode of a Diffuse Vacuum Arc , 1987, IEEE Transactions on Plasma Science.

[16]  G. Farrall,et al.  The movement of elongated metal particles under high‐voltage stress in vacuum , 1980 .

[17]  P. Osmokrovic,et al.  Surface-time enlargement law for gas breakdown , 2008, IEEE Transactions on Dielectrics and Electrical Insulation.

[18]  W. Egli,et al.  Use of integral arc models in circuit breaker testing and development , 1988 .

[19]  P. Osmokrovic.  Influence of switching operations on the vacuum interrupter dielectric strength , 1993 .