The Helios TSSD 2 is a speed controller equipped with two built-in transformers mounted on base runners, intended for use in V‑connection configurations. Designed for integration into switch cabinets, this unit is supplied without a housing. It offers terminal connections for five different voltage levels: 0, 80, 140, 280, and 400 volts. Operating at a frequency of 50/60 Hz, the TSSD 2 allows for precise and reliable control of 3‑phase fan speeds in enclosed electrical systems.