The Helios ESD 5 is a stepless electronic transformer controller engineered for the precise control of three-phase fans through voltage reduction. Incorporating microcontroller-based technology, it allows control via a 0 – 10 V analog signal or an electronic temperature controller such as the EKW 6.3. Multiple controllers can be operated in parallel for distributed ventilation control across several units. Built-in thermal contact monitoring protects the motor from overload. Compliant with EMC Class B standards, the system does not require shielded cabling between the controller and motor.