AC can be transported at high voltages from the power plant to consumers with low losses, but this applies only to distances up to approx. 600 kilometers. Over longer distances, high AC voltages have increased transmission losses. Direct current transmission is used instead as a cost-effective way to provide low-loss power supply and to use the electrical energy more efficiently.
HVDC transformers are part of the converter station at the beginning of the transmission line which converts AC to direct current. This process is then reversed at the end of the line. Converting AC to DC helps to transfer the energy efficiently while cutting line losses by 30-50%. As a core component of the Changji-Guquan HVDC line, the tested transformer brings the voltage to 1100kV DC level.