Pressure In Vacuum Interrupters Research Articles

Influence of Current Interruption Operations on Internal Pressure in Vacuum Interrupters

Due to the impact of arcing on high-purity surfaces and bound residual gases, current interruption operations may influence the internal pressure in vacuum interrupters (VIs). In this paper, we investigate the temporal development of internal pressure in VIs immediately after a current interruption operation, both intrusively using a vacuum gauge and nonintrusively using the magnetron method. By means of an experimental test setup that consists of a vacuum test system to vary the internal pressure in punctured, nonvented VIs with active getter elements, we performed experimental test series under variation of internal pressure and arcing time. The experimental results indicate that arcing during the interruption operation predominantly causes a significant decrease in the internal pressure of up to several orders of magnitude, depending on the arcing time and the initial pressure before the current interruption operation. Based on a test series with passivated getter elements, we found that active getter elements have only a minor influence on the observed pressure decrease. With regard to a condition assessment of vacuum circuit breakers, we discuss the impact of the observed pressure reduction effect on the possibility of predicting the remaining service life of installed VIs.

On-line monitoring of pressure in vacuum interrupters

Methods for on-line monitoring of the pressure in vacuum interrupters were investigated. Some experiments were carried out to investigate the characteristics of an inverted magnetron vacuum gauge in pulsed operation mode. According to the experimental results, a kind of vacuum chamber with intellectualized vacuum sensor was developed to implement the on-line monitoring of pressure in vacuum interrupters. The vacuum sensor can measure pressures ranging from 3times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> Pa to 0.5 Pa

Discharge Properties in Low Vacuum Region of Vacuum Interrupter Filled with SF6 Gas

This paper deals with the discharge properties in low vacuum region of practical vacuum interrupter filled with SF6 gas. In field, the vacuum interrupter inside the cubicle-gas insulated switchgear is surrounded by SF6 gas. If the leakages occur, the surrounding gas may invade the vacuum interrupter and increase the internal pressure. Thus, the pressures are set at 1.3 Pa to 2.6 kPa to simulate the leakage. The measurement of discharge occurring inside the vacuum interrupter was performed with a photomultiplier tube. From the result of the experiment, it is found that the pressure of vacuum interrupter below and above 50 Pa can be distinguished on the basis of the rise time, peak intensity and width of the discharge light pulse. The result reveals that the discharge pulses at pressures below 50 Pa have the relatively larger rise time of 100ns order, and larger pulse width of 2μs order. While, for pressures above 50 Pa, the rise time have relatively smaller value of 10 ns and pulse width of 0.1μs order. The result also shows significant difference in discharge characteristics compared with those in low vacuum of vacuum interrupter filled with air that we have investigated previously.

Measurement of emission currents immediately after arc polishing of contacts-Method for internal-pressure diagnostics of vacuum interrupters

The inherent high reliability of vacuum interrupters is determined by the maintenance of a high degree of vacuum in the vacuum tube for a long time. Rise of internal pressure exceeding a certain threshold value causes loss of the current switching capability and, at a pressure that is about one or two orders higher, the loss of the electric insulating properties. Pressure measurements after manufacturing and reexamining the internal pressure of vacuum interrupters after several years of service require different procedures, measuring methods, and diagnostic techniques. The fundamentals of a new method based on the measuring of emission currents immediately after arc polishing of the contacts are presented. This method is appropriate for estimating the internal pressure of the vacuum interrupters after long-time service and for giving information about the remaining safety margin. >