Medium Voltage Vacuum Circuit Breakers Switching performance impacting parameters Synopsis

The primary function of an electrical circuit breaker is to be capable of making, carrying and breaking currents under normal and abnormal circuit conditions such as those of a short circuit, and must operate reliably with proper mechanical characteristics to protect medium voltage power equipment and circuits. To ensure this reliability, the operating mechanical drive, the stored energy its transmission kinematics and dynamics the repartition of moveable and fixed masses, the balance between stiffness and damping of its main frame, the crucial strokes, and velocities of the moving contacts of vacuum interrupters during opening and closing operations, both bouncing, and friction phenomenon are all design parameters being more complex than it first appears. For proper current switching operations of Vacuum Circuit Breakers, many parameters being critical for short time current withstanding capacity of the system components, for short circuit current making and breaking and for capacitive current breaking operations were identified and analyzed. To assess the robustness and reliability of every circuit breaker newly developed, the behavior of most of these factors is now systematically taken under consideration and controlled to ensure expected high-quality level.