The resistance of titanium diboride (TiB2) particles will change significantly under the action of external force. So it can be used as a variable resistor for fault current limiting. For this purpose, TiB2 material is required to withstand large currents and voltages. Based on the previous research, the resistance variation characteristics of material under large currents are studied in this paper. Through experiments, the voltage’s withstanding capability of a material is studied under large resistance. It is found that the maximum voltage that the material can withstand is related to its physical properties and material size. Then, a prototype based on the fast repulsion mechanism is made. Experiments are carried out on the current limiting capability of granular material under different sizes. The experimental results show that the granular material has good current limiting capability. The larger the material size is, the better the current limiting effect is.
This paper establishes a three-dimensional numerical model of a 12 kV gas ring main unit in a C4F7N/CO2 gas mixture during the interrupting process based on a magneto-hydrodynamic model, and uses FLUENT commercial software to simulate and analyze the arc motion and voltage characteristics of the existing 12 kV gas ring main unit interrupting structure in a C4F7N/CO2 gas mixture during the interrupting process. By applying a magnetic field to the interrupter chamber, the effect of magnetic field regulation on the arc motion pattern and arc voltage is investigated, showing that the external magnetic field can make the arc enter the grid more and the arc voltage can be increased, and the arc voltage value will be larger just before the current crosses zero. At the same time, based on the synthetic loop platform, the arc-extinguishing structure of the ring main unit before and after the magnetic field adjustment is studied for its breaking capacity, which shows that the ring main unit can withstand a larger recovery voltage under the action of the external magnetic field and is more conducive to the successful breaking of the ring main unit.
The application of SF6 gas in electrical equipment is gradually limited due to its greenhouse effect on the environment. The suitable alternative gases are studied to replace SF6. In this paper, the arc characteristics of SF6, N2, SF6/N2 mixture and dry air have been simulated in the ring main unit. The influence of different gases on the arcing process has been analysed.
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