Research On Model Design Of 12kV Rotation Disc Vacuum Circuit Breaker

Vacuum circuit breaker plays an important role of protection and control in the power system,it is one of the core power transmission and distribution equipment in the smart grid.With the continuous breakthrough of various core technologies and the development of new arc extinguishing chamber and operating mechanism,the technical parameters of the vacuum circuit breaker have been continuously improved.In the medium voltage power network,vacuum circuit breakers have been in a dominant position.In view of the miniaturization of vacuum circuit breaker,based on the previous research on vacuum interrupter,operating mechanism,contact material,characteristics of vacuum arc and breaking performance,a three-phase rotation disc vacuum circuit breaker has been proposed.However,there are still some problems such as main circuit insulation,three-phase synchronous opening and the operating mechanism design need to be further improved.Based on the study of the three-phase disc rotation vacuum interrupter in the early stage,this paper researched on the main circuit insulation and breaking capacity of the vacuum circuit breaker for a further performance improvement,and proposed a new structure and main circuit line layout model.In this new model,the main circuit distribution was changed from the same direction to the opposite,which shortened the length of the main circuit line as well as reduced the insulation load of the main circuit.Some adjustments were also made to the position of operating mechanism,and in the case of synchronous breaking,the miniaturization design was achieved.Besides,the flexible connection mode of the conductor was changed to reduce the impact force produced between the conductive rods and the end cap and then extended the mechanical life of the circuit breaker.Based on the numerical simulation of the three-dimensional electromagnetic field,the distribution of the electric field within the vacuum interrupter has been studied.The maximum of the field strength within the vacuum interrupter and the electric field intensity distribution at the breakdown position were analyzed and calculated to optimize the design of new model.In order to further improve the breaking performance of vacuum circuit breaker,a new type of two pole longitudinal magnetic contact is proposed in this paper.The 3-D finite element method is used to simulate the longitudinal magnetic field in the center of the contact arc,and the longitudinal magnetic field distribution of the available current peak current and current zero crossing time,as well as the lag time of the longitudinal magnetic field.Compared with the magnetic field distribution of the old bipolar longitudinal magnetic contact,the longitudinal magnetic field strength of the new type structure contact is stronger at the peak current,the current zero time is weakened,the lag time is relatively prolonged,and the new contact meets the improvement demand.The temperature field of the new vacuum circuit breaker model single-phase circuit conductor under rated working current and rated short-circuit current is calculated.The calculation results show that under the condition of rated short-circuit current,the temperature rise of circuit breaker can be satisfied only by adding heat sink.Finally,a new double E electromagnet operating mechanism and cylinder type permanent magnet linear motor operating mechanism are designed in this paper,combined with the special movement mode of the new three-phase rotation disc vacuum interrupter.The connection device which matches the motion of the three-phase rotation disc vacuum interrupter is also designed,and the assembly of the three-phase rotation disc vacuum interrupter and the operating mechanism is completed.The structure design and electromagnetic design of both the new double E electromagnet operating mechanism and cylinder permanent magnet linear motor operating mechanism are also carried out.It is proved that the cylinder permanent magnet linear motor operating mechanism has smaller structure size compared with the new double E electromagnet operating mechanism.The cylinder permanent magnet linear motor operating mechanism is more conducive to realize the miniaturization of the new three-phase rotation disc vacuum circuit breaker,which provides a theoretical reference for further improvement of the product design.