The Influence of the Dispersion in Pre-arcing Time of Vacuum Circuit Breakers on the Controlled Switching of Capacitor Banks

The phase selection control vacuum circuit breaker (VCB) is an effective measure to suppress the inrush current when closing the capacitor bank. The accuracy of phase selection is affected by the pre-arcing time of the VCB and dispersion. This paper mainly uses the methods of experiment and simulation to study the influence of the pre-arcing time and dispersion of VCBs with cup-type axial magnetic field (AMF) contacts and spiral-type transverse magnetic field (TMF) contacts on phase selection to suppress inrush current. Firstly, the pre-arcing time of the VCB with two different contacts is measured through experiments and dispersion is calculated. Secondly, a simulation circuit based on the actual 40.5kV VCB switching capacitor bank experimental circuit parameters is established to calculate the inrush current amplitude in the two different phase control modes. Finally, the inrush current amplitude based on different phase selection methods are compared. The comparison results show that compared with the phase selection method based on the contact touched time of the vacuum interrupter, the phase selection method based on the pre-arcing time t
50
is more conducive to suppressing inrush current. Compared with the cup-type AMF contacts VCB, the spiral-type TMF contacts VCB has a smaller pre-arcing time and dispersion.