This control panel is designed for continuous speed adjustment of fans with voltage-controlled single-phase induction motors. The rotational speed is controlled by lowering the voltage using power thyristors (phase cutting control) over the entire range of 0 - 230V. Several fans can be connected to the device if the sum of the individual currents does not exceed the rated device current. The operation is done on the device's rotary switch. On the inside of the device, there is an adjustment screw which allows for the setting of the minimum speed of the fan.