Power factor correction (PFC) controllers are not a specific brand but a category of devices used to improve power efficiency in electrical systems. Leading manufacturers of PFC controllers include companies like Schneider Electric (France), ABB (Switzerland), Siemens (Germany), and Eaton (USA). These devices are widely used in industrial, commercial, and utility sectors to reduce energy waste, lower electricity costs, and comply with regulatory standards. PFC controllers adjust the phase relationship between voltage and current, optimizing power usage in applications such as motor drives, HVAC systems, and renewable energy installations. Key products include static PFC units, automatic capacitor banks, and hybrid solutions integrating reactive power compensation.