Measurement and simulation analysis of internal pressure in arc chamber of low-voltage molded case circuit breaker

Lijun Wang,Yujie Wang,Shenli Jia,Yujie Li

doi:10.1063/1.5030964

Abstract

During the arc interruption process, the internal pressure in the arc chamber of a molded-case circuit breaker (MCCB) rises rapidly. In this study, the arc behavior and internal pressure in an MCCB are measured and calculated. First, using computational fluid dynamics, the internal pressure in the arc chamber is computed both with and without a baffle. In the presence of the baffle, it is found that the pressure is similar at various measurement points, whereas without the baffle, obvious differences in pressure are observed. Second, a moving model considering the contact opening process is proposed based on the relationships between the arc positions, arc area, and source terms at a typical point in time. Compared with a fixed arc model, the moving arc model provides a more precise arc distribution and pressure in the arc chamber of an MCCB.

Highlights

Damage to the arc chamber of a low-voltage (LV) molded-case circuit breaker (MCCB) may result in issues that affect the safety of electrical workers
This paper describes how the internal pressure in the arc chamber of an LV MCCB can be calculated using computational fluid dynamics (CFD)
In the absence of a baffle, the pressure in the arc chamber is significantly lower than when a baffle is present

Summary

Introduction

Damage to the arc chamber of a low-voltage (LV) molded-case circuit breaker (MCCB) may result in issues that affect the safety of electrical workers. When the arc of an MCCB is interrupted, the temperature and pressure in the arc chamber rise quickly, creating a pressure difference between the inside and outside of the chamber. The high temperature and pressure can cause higher local stress, deformation, and fracture, resulting in permanent damage to the shell of the arc chamber. To avoid such failures, it is necessary to calculate the pressure inside the arc chamber during the arc interruption process.[1]. The pressure and the influence of fluctuations during the arc initiation stage have been calculated by Lindmayer and Springstubbe.[8]

Methods

Results

Conclusion