The Elta 149-TC35 is a 3‑phase transformer speed controller rated for up to 5 amps, providing five stepped fan speed settings. It features an IP40-rated enclosure and is suitable for use in ambient temperatures up to 40°C. Designed for noise-sensitive environments, it avoids the magnetic hum associated with stepless speed controls. Note: the illuminated on/off switch and type D MCB protection apply only to single-phase versions.