Minimum arcing interruption performance of a 126 kV single-break vacuum circuit breaker with 3/4 coil-type axial magnetic field contacts

摘要

The objective of this paper is to determine minimum arcing interruption performance of a 126 kV single-break vacuum circuit breaker with 3/4 coil-type axial magnetic field (AMF) contacts. The full contact gap was 50 mm. A spring type mechanism was used to provide an average opening velocity of 3.0 m/s within 20 mm after contacts separation. Test duty T100s experiment with a rated short circuit current of 40 kA rms was carried out by using current injection synthetic test method. The experiment results showed that the minimum arcing time was determined as 4.8 ms. The corresponding minimum arcing contact gap was determined as 14.4 mm. Further analyses indicated that with increasing of contact gap from 11.7 to 25.8 mm in the experiment, phase shift time decreased from 0.84 to 0.63 ms. While residual axial magnetic flux density at current zero decreased from 153.25 to 89.97 mT. Phase shift time and residual axial magnetic field of 126 kV single-break vacuum circuit breaker at minimum arcing contact gap were 0.77 ms and 136.22 mT, respectively.