Numerical Analysis On Electromagnetic Field Of 110kV Vacuum Circuit Breakers

Recently, people pay more attention to human living environment in the world, and SF6 is limited to be used and be let out, so the development of SF6 circuit breakers are restricted. On the contrary, excellent insulation and arc blowing out characteristics of vacuum are used sufficiently for vacuum circuit breakers(VCB) which do not make pollution of environment, so middle voltage vacuum circuit breakers have been highly developed, and VCB with high voltage and large capacity have become considerably interested in the world. It is predictable that high voltage VCB would certainly be replaced high voltage SF6 circuit breaks in the future.Because vacuum interrupter is the heart of vacuum circuit breakers, its design is the key to vacuum circuit breaker development. In this thesis, 110kV vacuum interrupter is simulated and analyzed on the electromagnetic field, and some references are supplied for the development of 110kV vacuum circuit breakers. The static electric field of 110kV vacuum circuit breakers is simulated and analyzed using finite element method, influences of size and position of various shields on the electric field distributions of inner interrupter are gotten, and influences of contact gap length and rain shed on the electric field distributions of inner interrupter are given also. Then according to specific conductivity of plasma and metal vapor, calculation equations are deduced for vacuum interrupter from Maxwell equations, and two-dimensional electric field is solved using finite element method. The effect of charged particle on the electric field distribution of inner interrupter is calculated and analyzed with the consideration of existential charged particle on the surface of contact and floating conductor during dissipating of particle in post-arc, furthermore the proposal is given to make the electric field distributions more uniformly.According to the physical model of high-current vacuum arc, contract effect of vacuum arc self-magnetic field and its influence to arc are analyzed based on the theory of magnetic field force applied to current, and electromagnetism pressure distribution generated by self-magnetic field of arc is given. At last,the action of additional-axial magnetic field to reduce self-magnetic field contract effect is analyzed.3-Dimentional electrode model of two segments coil and three segments coil axial magnetic field (AMF) contacts of 110kV vacuum interrupter are built up, and the 3-D static magnetic field and eddy current field in the case of arc discharge are simulated by the 3-D finite element method. The distributions of AMF on the surface of contact plate and mid-gap plane are gotten at current peak and zero respectively. Furthermore the distributions of the AMF phase shift time along the axial and radial path are given at current zero. At last, the parameters of these two contacts are compared.