An Approach to Enhance the Controlled Switching of Circuit Breakers Equipped with Preinsertion Resistors for Power Capacitor Banks

The controlled switching of capacitor banks when properly parameterized brings significant benefits to the bank, circuit breaker, and adjacent equipment by significantly reducing the levels of inrush currents. This article explores and analyzes the waveforms from a circuit breaker equipped with both preinsertion resistors (PIR) and a controlled switching device (CSD), proposing a dynamic approach to determine the better closing times for both the PIR and the main contact of the circuit breaker, thereby reducing inrush current levels and improving system performance and reliability. The study employs a computational tool to identify the circuit breaker’s contacts insertion points, presenting important information such as the best closing instant for the main contact, the determination of preinsertion time, and maximum inrush current peak. The waveforms used in the study originate from both a real power shunt capacitor bank from a Brazilian substation and simulations modeled using the Alternative Transient Program (ATP). This dynamic approach not only reduces inrush current levels, but also contributes to increasing the useful life of the capacitor bank elements, the circuit breaker itself, and neighboring equipment.