For controlling two fans or ventilators with up to 3 levels using relays in step or changeover switching. The device also has a potential-free switching output for controlling accessories such as flaps or valves. Alternatively, the second fan output can be used as a 3-way switching output with a common potential.
The fan level can be selected directly, increased and decreased, and controlled via the control variables of an external controller. It is also possible to override the fan level using forced control. Furthermore, error monitoring and fan run-on can be parameterized using the ETS application.