Output devices are actuators or controllers that translate the signals in a control circuit into an action. Actuators (e.g. relays) or dimmers operate or control the light output through voltage changes. Controllers have their own processors and send signals to the control gear.
A relay is a switch that is activated by electric current. When operating metal halide lamps, a run-up time of several minutes and a longer cooling-down phase before re-ignition must be taken into account.
The dimmer is used for the infinitely variable regulation of the output from a light source. Leading edge control is applied to incandescent lamps. Low-voltage halogen lamps with electronic transformer are dimmed using trailing edge technology. Thermal radiators such as tungsten halogen lamps are easy to dim. Fluorescent lamps require special control gear, while compact fluorescent lamps require special electronic control gear units. Conventional compact fluorescent lamps cannot be dimmed. LEDs can easily be dimmed with the appropriate control gear.
In analogue 1V-10V technology, dimming is possible by using a special ECG with input for the 1V-10V control voltage and a potentiometer or a control system supplying analogue 1V-10V control voltage, such as the ERCO Area Net or KNX actuators. The dimmers are often installed in switch cabinets. The control lines are permanently connected to luminaires or groups of luminaires. The digital control protocol, DALI, on the other hand, allows for the individual control of the dimmable ECGs for all the connected luminaires.
Controllers are electronic units for process control. A lighting control system such as the Light System DALI saves light scenes and controls the luminaires. The amount of data which can be used to store the settings is limited by the storage capacity of the controller. The user operates the controller via software or a control panel. A control line establishes a connection to the luminaires and transmits the signals to the control gear.
In a LON system, D/A modules are used to save and recall light scenes. As output devices, they allow the connection of external dimmers or direct control of dimmable ECGs or transformers.