Sensor dimmer and relay modules (Dxx and Rxx / EDxx and ERxx) provide feedback regarding the state of each circuit in the module. As a general rule, under normal conditions (load connected and the MCB on), both the Signal and Power LEDs should be in the same state regardless of signal level.
The signal LEDs are always green. The power LEDs are green in European modules, and red in US modules - but some old European modules may also have red power LEDs. The colour is not relevant; only the on or off state conveys information.
|LED status||Dimmer modules||Relay modules|
|Signal off, Power off||Level at 0, Load connected||Level at 0|
|Signal On, Power On||Level greater than zero, Load connected and on||Level greater than zero, MCB on|
|Signal On, Power Off||Level at greater than zero, MCB off||Level greater than zero, MCB off|
|Signal Off, Power On||European Modules: Level at 0, No load connected
US Modules : Abnormal state