Electrical appliance for connection to an AC supply and a control method

1. A luminaire comprising:

a lighting element having different output lighting levels;

a first input adapted to be connected to an AC supply;

a battery integrated with the luminaire;

a second input ( 16 ) adapted to be connected to the battery;

a power converter connected to the first input and adapted to convert AC power from the AC supply to power the lighting element;

an interface adapted to receive a control signal identifying a power factor associated with the AC supply, wherein said control signal is associated with the lighting element and depending on the different output lighting level; and

a controller adapted to:

select an amount of power to be supplied from the first input to the lighting element or an amount of power to be supplied from the second input to the lighting element based on the power factor associated with the AC supply and according to said control signal, wherein the power factor indicates a ratio between a real power and an apparent power associated with the AC supply.

2. The luminaire as claimed in claim 1 , wherein the controller is adapted to select an amount of power to be supplied from the first input and an amount of power to be supplied from the second input to the lighting element, further according to the prevailing total power, kVA, and real power energy tariff.

3. The luminaire as claimed in claim 1 , wherein said controller is adapted to isolate the power conversion from the AC supply when selecting power from said second input.

4. The luminaire as claimed in claim 1 , wherein said controller is adapted to select power from only one of the first input and said second input according to said control signal.

5. The luminaire as claimed in claim 1 , wherein said controller is adapted to select the second input in response to the control signal indicating a power factor of the luminaire itself lower than a first threshold and/or select the first input in response to the control signal indicating a power factor of the luminaire itself higher than a second threshold.

6. The luminaire as claimed in claim 5 , wherein said interface comprises:

a detector to detect the power factor of the power converter; or

a communication module to receive the control signal from a remote device which is coupled to a set of electrical luminaires including the present electrical luminaire.

7. The luminaire as claimed in claim 1 , wherein said different output lighting levels comprises at least any one of:

different output brightness;

different output color/color temperature; and

different beam angle.

8. The luminaire as claimed in claim 1 , wherein said controller is adapted, at off peak hours, to:

determine if a power factor of the power converter itself is higher than a third threshold, and if it is:

to select the first input in response to the control signal indicating that a power factor of a system of other appliances is lower than a fourth threshold; and

to select the second input in response to the control signal indicating that the power factor of the system of other appliances is higher than the fourth threshold.

9. The luminaire as claimed in claim 1 , wherein the power factor associated with the AC supply comprises the combination of the harmonic power factor and the displacement power factor.

10. A system of appliances connected to a shared AC supply, wherein at least one appliance is the luminaire as claimed in claim 1 , and wherein the system further includes one or more of:

a heating, ventilation and air conditioning appliance; and

IT system appliances.

11. A method controlling an electrical luminaire having an output lighting element having different output lighting levels, comprising:

providing access to an AC supply to the luminaire and performing power conversion thereby to convert AC power from the AC supply for supply to the lighting element;

providing access to an battery integrated in the luminaire;

receiving or generating a control signal relating to a power factor associated with the AC supply, wherein said control signal is associated with the lighting element and depending on the different output lighting levels; and

selecting an amount of power to be supplied from the AC supply or an amount of power to be supplied from the battery to the output lighting element based on the power factor associated with the AC supply and according to said control signal, wherein the power factor indicates a ratio between a real power and an apparent power associated with the AC supply.

12. The method as claimed in claim 11 , wherein the step of selecting is for only selecting the battery in response to the control signal indicating a power factor of the luminaire itself lower than a first threshold and/or only selecting the AC supply in response to the control signal indicating a power factor of the luminaire itself higher than a second threshold.

13. A non-transitory computer readable medium comprising instructions when executed by one or more processors of a computer, cause the one or more processors to perform the method of claim 12 .

14. The method as claimed in claim 11 , wherein said different output lighting levels comprises any one of:

different output brightness;

different output color/color temperature; and

different beam angle.