The evaluation of heat losses in excitation systems of synchronous generators is a vital part of its design process. The excitation system includes an excitation transformer and an excitation cabinet, which are sources of additional heat losses in the electrotechnical complex. The excitation cabinet contains thyristor-rectifier, AC and DC busbars, fuses and cooling system, which has strong influence on the thermal mode of semiconductor valves and their heat losses. This work covers only air-cooling system. The water-cooling systems are out of scope of this work. Since the transformer losses are well-described in literature this work is focused on heat losses of excitation cabinet equipment. To minimize design errors when calculating the heating rate of the thyristor converter we consider structure of cabinets, mutual influence of different components and environment parameters. The computer program was developed in Matlab in order to include proposed estimation method to design process.
