Abstract
To void breakdown between busbars, the dissociation unit is applied in the arc chamber of an air circuit breaker (ACB) to cool down the hot gas exhausted from the vent of the arc chamber in the interrupting process. Cooling efficiency and flow resistance of the dissociation unit have important roles, which can greatly affect the safety of the low voltage switcher and interrupting performance of the arc chamber. The most common structure style of the dissociation unit is a multilayer metal wire mesh, and it has a complex microstructure. Then, it is unreasonable to directly simulate the dissociation unit due to the huge cost of calculation. In this study, the porous medium model is introduced and a combination of two different porous materials is applied to simplify the simulation model of the dissociation unit. Based on the porous model and simplified arc chamber model, the ACB with the dissociation unit is analyzed. The cooling effect and flow resistance of the dissociation unit are evaluated in the breaking process. By comparing experimental and simulated pressures in the arc chamber, this simulation approach is verified.
Highlights
During the breaking process of an air circuit breaker (ACB), high-temperature plasma fills the whole arc chamber and pressure in the chamber is high to several atmospheres
In order to establish the simulation model of the arc chamber with the dissociation unit, three studies are accomplished in our works: 1. The 3D simplified model and 2D equivalent model of the multilayer metal wire mesh are established and the cooling process of the hot gas flowing through the mesh is simulated
A combination of two different porous medium materials is introduced to simulate flow and heat exchange characteristics of the gas flowing through the multilayer wire mesh
Summary
During the breaking process of an air circuit breaker (ACB), high-temperature plasma fills the whole arc chamber and pressure in the chamber is high to several atmospheres. To eliminate breakdown risk between the busbars, the dissociation unit is generally installed in the arc chamber of the ACB to cool high-temperature quenching gas in the breaking process. Characteristics of flow and heat exchange of the hot gas in the arc chamber during the breaking process are completely different from general application conditions of the dissociation unit. The model of the multilayer metal mesh is established to investigate the dissociation process of the hot gas. In order to simplify the simulation model of the dissociation unit, the porous medium model is introduced to equal the multilayer metal mesh filter. With considering the influence of the dissociation unit, temperature and pressure fields in the arc chamber are simulated during the breaking process of the ACB.
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