Study on the reignition phase and magnetic field simulation of drawn vacuum arc in 126 kV axial magnetic field contacts

With the increase in breaking voltage level, studying the evolution characteristics of reignition of high-current vacuum arc plays an important role to improve the breaking capacity of vacuum circuit breakers. In order to analyze the characteristics of the arc in the reignition phase of 126 kV axial magnetic field (AMF) contacts, drawn vacuum arc experiments were conducted in a detachable vacuum chamber and magnetic field simulations were performed under corresponding conditions. By analyzing the arc images and arc-voltage characteristic of high-current interruption experiments with a pair of 140-mm-diameter cup-type six-slot AMF contact, the arcing reignition process in the second half-wave can be divided into four stages, i.e., reignition stage, disordered movement stage, dispersed arc stage, transition stage, and diffused arc stage. Combined with the magnetic field simulation analysis, at the beginning of the second half-wave just after current zero, the axial magnetic field is weak, resulting in poor control over the arc, while the transverse magnetic field is strong, promoting rotational motion of the arc along the contact surface. In this process, the arc voltage presents significant noise. As the current increases and the axial magnetic field strengthens, the control of the arc gradually improves. The arc transitions from dispersed mode to diffused mode after the current peak. At the same time, cathode spots continuously spread on the contact surface, the arc voltage gradually becomes stable, and the arc extinguishes at the second current zero.