Analysis of DC Fast Circuit Breaker Opening and Arc Extinction in Urban Rail Transit Traction Power Supply System

Objective Arc extinction technology for DC (direct current) is one of the design challenges in urban rail transit traction power supply systems. Therefore, it is necessary to analyze the principles of DC opening and arc extinction for main DC fast circuit breakers. Method The principles of DC current interruption and arc extinction are introduced. The stable burning point and extinction conditions of DC current are discussed. Parameters for DC arc interruption are analyzed with an introduction to the arc extinction design principles of DC fast circuit breakers. Causes for the easy burning damage of DC fast circuit breakers in metro power supply systems are examined. Result & Conclusion To interrupt a DC arc, higher arc voltage than the power supply voltage is required, because increasing the arc voltage can extinguish the DC arc. The opening process of DC fast circuit breakers needs to consider both the arc burning time and system overvoltage factors. During the design and development of DC circuit breakers, attention should be paid to non-stable arc voltage and arc voltage for small current interruptions. During arc extinction, setting an additional RC (resistor-capacitor circuit) blowout coil during arc extinction, with the design of metal grids in the arc extinction chamber, can stabilize the arc voltage.