Thermal Margin Determination for Safe Operation of VCBs in Smart Grids

The thermal performance of vacuum circuit breakers (VCBs) is rigorously evaluated under both normal and fault conditions to provide insights into their reliability and lifetime. Utilizing COMSOL Multiphysics software, a detailed simulation model was developed to investigate the temperature distribution and potential thermal risks within the VCB. Results demonstrate a significant correlation between ambient conditions and operating currents on the VCB's temperature. While the VCB's steady-state temperature remains within acceptable limits during normal operation, short-circuit current can lead to rapid temperature increases, potentially exceeding critical thresholds. To ensure safe and reliable operation, the proposed temperature margin approach aims to safeguard the VCB from thermal overload. A safety margin is created by establishing a critical temperature limit to prevent excessive temperature rise and potential damage to the VCB. In addition, ambient temperature emerges as a critical parameter in the selection and performance of VCBs. Increasing ambient temperature leads to additional thermal stresses in the internal components of VCBs, directly impacting their lifespan and reliability. Analyzing the thermal behavior of VCBs under various temperature conditions provides valuable insights for the thermal monitoring of VCBs.