Harmonic losses measurement at rated current and rated voltage in 12 pulses high current controlled transformer-rectifiers

In this paper, an experimental test to obtain losses at rated current and rated voltage of 12-pulse high current transformer rectifier is presented. Normally the electric power capability at the factory is small in comparison with the rated power of this type of transformer-rectifier and tests at factory refer usually to routine short-circuit and no load tests. In most cases, the 12 pulse configuration is formed by two 6 pulse high power transformer rectifiers in parallel. Additional losses due to harmonics are obtained at rated current and rated voltage using the proposed method presented in this paper. This method connect both rectifiers in antiparallel in such way that one of them operates as a rectifier and the other as an inverter. The active power required from the network is just only the total losses. The reactive power for this test must be evaluated for each specific case