This chapter examines the effects of FCLs on power grid operation, which can be either beneficial or detrimental depending on the application context. It analyzes the impact of FCLs on key operational parameters such as system reliability, active and reactive power flow, and overall grid stability. While FCLs can enhance security, their integration can also introduce new complexities. The chapter also addresses key design challenges, including reactor saturation in the core, the cost-benefit trade-off, and the appropriate sizing of FCLs for different grid configurations. The chapter provides a comprehensive framework for assessing the performance of FCLs by evaluating these technical and economic factors. The insights presented are intended to support informed decision-making regarding the feasibility and optimal deployment of FCL technologies in modern power grids. ... Read more