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The high voltage circuit breaker plays an important role in the circuit. In order to extend the service life of the circuit breaker, it is necessary to have materials with excellent ablation resistance. At present, The PTFE with boron nitride (BN) is widely used to produce the nozzle of high voltage circuit breaker. With the increase of BN filler particle size, the arc ablation performance of the composite increases gradually. In order to obtain the nozzle material with excellent ablation performances, nanoscale and microscale h-BN were divided into five groups with different mass ratio, then added into PTFE to prepare five kinds of composite materials with constant BN mass fraction. To study the influence of mass ratio on the thermal conductivity and arc ablation characteristics of PTFE/BN composites, arc ablation, thermal conductivity and spectral reflectance are tested. After adding microscale and nanoscale hybrid BN, the ablation amount of the composite decreased firstly and then increased, reaching the minimum in the third group. This work indicates there is a certain proportion with the excellent performance in arc ablation characteristics. This paper offers a feasible method for the preparation of PTFE/BN high-voltage circuit breaker.

As an important part of power equipment, high voltage circuit breakers play an important role in circuit breaking and isolating. However, during the breaking process of high voltage circuit breakers, arcs and recovery voltages are generated between the moving and stationary contacts, which may cause serious ablation and breakdown of the nozzles in the circuit breaker, shortening the life of the circuit breakers. Therefore, nozzles with superior performance are urgently needed. PTFE filled with different proportions of micron-BN and nano-BN was prepared in this paper to study the effect of hybrid fillers on the AC breakdown performance of PTFE. Scanning electron microscope (SEM) is used to characterize the dispersion state of micron-BN sheets and nano-BN sheets in PTFE matrix. The Thermally stimulated depolarization currents (TSDC) experiment is used to test and calculate the trap parameters of the sample. The AC breakdown experiment is used to test the breakdown strength of the specimen. The relationship between the breakdown performance and the change of trap parameters is discussed. And these factors are considered to be closely related.