Influence of the Contact Opening Speed on DC Vacuum Arc

Abstract

Arc determines whether the vacuum switchgears can break current successfully, so it is significant to study its characteristics. In this paper, a hybrid high-speed actuator was designed, and a method of forced current zero was used to interrupt dc in a synthetic test circuit. With the different contact opening speeds, the processes of arc burning and current transferring were observed by a high-speed CMOS camera. Through the arc area obtained by an image processing technology, the influences of the opening speed on arc were researched, including the influences in the initial arc burning stage, in the forced current zero stage, and at the same electrode distance. The results indicate that with the increase of the opening speed in a certain range, the arc area in the forced current zero stage tends to be small, and the one in the initial arc burning stage spreads more quickly. Although the arc area increases with the opening speed in the initial arc burning stage, its impact on the whole dc current transferring process is slight when the contact opening speed is high. So, high opening speed is helpful to extinguish arc and transfer current. In addition, there is another discovery in the experiments. In a certain range, when the opening speed is higher, arc burns stably earlier, and the arc area is smaller in the stable burning stage. So, it is beneficial to inject the transferring current in this stage. Experimental results and analysis of the arc images prove that increasing the opening speed is useful to transfer the current successfully and recover the dielectric strength of the electrode distance.Index Terms-DC interruption, forced current zero, highspeed actuator, image process, vacuum arc.

Effect of adding impedance for current balancing on the vacuum arc commutation characteristics of DC microgrid hybrid circuit breakers

“…7(c), Fig. 11(a), and the literature [14] that both U arc and V arc increase with the increase of the main current, and according to Formula (16), under the condition that the vacuum arc commutation can be successfully completed, the increase of V arc means that a larger R a can be added. The curve of key parameters with and without externally applied TMF is shown in Fig.…”

“…Figures (c) and show that V arc > V IGBTs should be ensured for the successful completion of vacuum arc commutation. In addition, there will be various deviations of arc voltage of the vacuum breaker caused by the opening timing of contacts, surface condition of contacts, and circuit inductance and resistance . Thus, some margin will be necessary for the voltage difference between V arc and V IGBTs , which is that V arc > V IGBTs + Δ U should be ensured for the successful completion of vacuum arc commutation, where Δ U is some margin for the secure test conditions.…”

“…As shown in Fig. 7(c), when the stringing impedance does not satisfy Formula (16), it may cause failure of vacuum arc commutation. As shown in Formula (3) and Fig.…”

Hardware implementation of series DC arc fault protection using fast Fourier transform

“…5, October 2021: 1679 -1687 1680 detection of series DC arc fault. For example, Physical indication can be seen when arcing process such as light and temperature [5], [6]. However, physical indication difficult to implemented because do not know happen of series DC arc fault and physical indication changes corresponding of series DC arc fault.…”