OTLM (Overhead Transmission Line Monitoring) system is a system solution for monitoring and rating of overhead lines based on real- time monitoring of conductor temperature, load, sag (clearance), and weather conditions. OTLM system supports more efficient operation of OHLs by enhancing safety and flexibility of grid operations. The system enables safe utilisation of maximum OHL capacity – ampacity while taking into account weather and load conditions. The system delivers measurements of conductor conditions (temperature, sag – clearance, icing detection and calculated ampacity). OTLM Center (server software) supports dynamic line rating of OHL which can be included in the existing SCADA system.