刘志远

Date:

2025-04-30

Title of Paper:

Critical radius of axial magnetic-field contacts in vacuum interrupters

Journal:

IEEE Trans. Power Delivery

Summary:

Vacuum circuit breakers (VCBs) are widely used to protect medium-voltage (MV) power distribution circuits. Since
SFgas is specified as a global warming gas, VCBs are steppinginto a higher voltage sector to protect power transmission circuits.Axial magnetic field (AMF) contacts are widely used in vacuum
interrupters. In this paper, we propose a concept of critical ra-dius of AMF contacts. When coil width and coil height are fixed,the axial magnetic flux density increases first with increasing con-tact diameter. Then, it reaches a maximum value. Thereafter, theaxial magnetic flux density decreases. The contact radius corre-sponding to the maximum axial magnetic flux density is critical ra-dius. The concept of critical radius is validated by coil-type AMFcontacts and slot-type AMF contacts in MV vacuum interrupterswith finite-element analysis. Critical radius is only related to con-tact geometry parameters and the current has no influence on crit-ical radius. Critical radius increases with increasing contact gap,coil width, coil height, and thickness of the contact plate. In high-voltage AMF vacuum interrupters, axial magnetic flux density perkiloampere increases with increasing contact diameter since thecritical radius is typically high with a high contact gap and it isin the rising branch. In an MV AMF vacuum interrupter, inter-rupting capacity could increase with an increase of the contact di-ameter with a different rising rate before and after the critical ra-dius. This is expected to be experimentally validated.

Co-author:

Liu zhiyuan,Wang zhongyi,Zheng yuesheng,Wang jimei

Volume:

Vol.24, No.2

Page Number:

672-678

Translation or Not:

No

Date of Publication:

2009-04-20