Successful commissioning of a monitoring system for 6 transformers at 110 and 220 kV voltage levels. Data is transmitted to the control room - where the system's server is located - via fiber optic cables without any interference. The system reports an alarm to the operating personnel fully automatically when critical partial discharge values are reached and is connected to the switchgear's data acquisition system via a SCADA interface. The transformers are equipped with 5 UHF PD measuring sensors, which enable the partial discharge in the transformers to be detected and localized.