The electrical energy conversion laboratory located in the electrical engineering workshop environment is a room for students majoring in electrical engineering education at Universitas Negeri Medan for electrical machinery practice activities. NV7017 Three-Phase Synchronous Generator Lab Trainer is used to practice electrical machines for students. From the observation results, this trainer contains a total harmonic distortion current of 82.1%. After research using an LC filter, it can reduce the content of harmonic currents that appear to be 14.28%. The results obtained are good but according to the IEEE 519 -2014 standard for ⁄ for a 220-volt system voltage, the permissible third-order individual harmonic distortion current (IHDi) is 7%, while the research results obtained are 12.65%. So it is necessary to conduct further research in order to determine other types of harmonic filters that can reduce harmonic currents according to IEEE 519 -2014 standards.