Method and system for luminance characterization

1. A system for luminance characterization of a luminaire comprising:

a ballast coil;

a multi-tap capacitor connected in series with the ballast coil, wherein the multi-tap capacitor has a plurality of tap capacitors integrated into a capacitor housing;

a plurality of switches, wherein each switch is coupled to one of the plurality of tap capacitors for selectively coupling the tap capacitors together to produce a multi-tap capacitance corresponding to a configuration of the plurality of switches;

a lamp connected in series with the multi-tap capacitor and the ballast coil;

a photometer located to measure light intensity of the lamp and to produce a lumen output measurement; and

a memory for storing a database having a plurality of lumen output measurements corresponding to each multi-tap capacitance, wherein each multi-tap capacitance corresponds to one of a set of all configurations of the plurality of switches.

2. The system for luminance characterization according to claim 1 comprising a processor coupled to the photometer and the memory for reading the lumen output measurements and recording the lumen output measurements in the database.

3. The system for luminance characterization according to claim 1 comprising a power meter coupled to a power supply that is coupled to a power input of the ballast coil for measuring power consumption of the luminaire.

4. The system for luminance characterization according to claim 3 wherein the power meter measures real power consumption and a power factor.

5. The system for luminance characterization according to claim 1 wherein the plurality of switches is a plurality of electronic switching elements.

6. The system for luminance characterization according to claim 1 wherein the plurality of switches is a plurality of relay switches.

7. The system for luminance characterization according to claim 2 wherein the processor is coupled to the plurality of switches for configuring the switches through all of the configurations of the plurality of switches.

8. The system for luminance characterization according to claim 1 wherein the multi-tap capacitor comprises a base capacitor integrated into the capacitor housing, wherein the base capacitor has first and second terminals connected, respectively, to a first and a second connector lug, wherein each of the plurality of tap capacitors has a first tap capacitor terminal and a second tap capacitor terminal, wherein the first terminal of the base capacitor and each of the first tap capacitor terminals is connected, respectively, to a corresponding connector pin in a multi-pin connector, and wherein the second tap capacitor terminals are connected to the second terminal and the second connector lug, wherein the multi-tap capacitance is measured between the first and second connector lugs, and can be configured to be equal to the base capacitor value plus values of one or more selected tap capacitors connected in parallel with the base capacitor by the plurality of switches.

9. The system for luminance characterization according to claim 8 wherein the multi-tap capacitor has (t) number of tap capacitors, and wherein the t tap capacitors have a capacitance value (C x ) where

C

x

=

C

tap_tot

⁢

(

2

t

-

x

)

2

t

-

1

for x equal 1 to t, where C tap — tot has a value equal to the difference between a capacitance value for operating the luminaire at a minimum brightness and a capacitance value for operating the luminaire at a maximum brightness.

10. The system for luminance characterization according to claim 8 wherein the base capacitor has a capacitance value selected to operate the luminaire in a minimum brightness mode.

11. A method for luminance characterization of a luminaire comprising:

providing a ballast coil;

connecting a multi-tap capacitor in series with the ballast coil, wherein the multi-tap capacitor has a plurality of tap capacitors integrated into a capacitor housing;

coupling a plurality of switches to each one of the plurality of tap capacitors for selectively coupling the tap capacitors together to produce a multi-tap capacitance corresponding to a configuration of the plurality of switches;

connected a lamp in series with the multi-tap capacitor and the ballast coil;

locating a photometer to measure light intensity of the lamp and to produce a lumen output measurement; and

storing a database in a memory, wherein the database has a plurality of lumen output measurements that correspond to each multi-tap capacitance, wherein each multi-tap capacitance corresponds to one of a set of all configurations of the plurality of switches.

12. The method for luminance characterization of a luminaire according to claim 11 wherein the storing a database in a memory comprises stepping through configurations of the plurality of switches and storing the lumen output measurements in response to each configuration of the plurality of switches.

13. The method for luminance characterization of a luminaire according to claim 11 wherein connecting a multi-tap capacitor comprises connecting a multi-tap capacitor having a base capacitor integrated into the capacitor housing, wherein the base capacitor has first and second terminals connected, respectively, to a first and a second connector lug, wherein each of the plurality of tap capacitors has a first tap capacitor terminal and a second tap capacitor terminal, wherein the first terminal of the base capacitor and each of the first tap capacitor terminals is connected, respectively, to a corresponding connector pin in a multi-pin connector, and wherein the second tap capacitor terminals are connected to the second terminal and the second connector lug, wherein the multi-tap capacitance is measured between the first and second connector lugs, and can be configured to be equal to the base capacitor value plus values of one or more selected tap capacitors connected in parallel with the base capacitor by the plurality of switches.

14. The method for luminance characterization of a luminaire according to claim 13 wherein the connecting a multi-tap capacitor comprises connecting a multi-tap capacitor having (t) number of tap capacitors, and wherein the t tap capacitors have a capacitance value (C x ) where

C

x

=

C

tap_tot

⁢

(

2

t

-

x

)

2

t

-

1

for x equal 1 to t, where C tap — tot has a value equal to the difference between a capacitance value for operating the luminaire at a minimum brightness and a capacitance value for operating the luminaire at a maximum brightness.

15. The method for luminance characterization of a luminaire according to claim 13 wherein the connecting a multi-tap capacitor comprises connecting a multi-tap capacitor wherein the base capacitor has a capacitance value selected to operate the luminaire in a minimum brightness mode.

16. The method for luminance characterization of a luminaire according to claim 11 comprises:

connecting a power meter to a power source of the ballast coil;

measuring a power consumption of the luminaire for each configuration of the switches; and

storing the power consumption in the database.

17. The method for luminance characterization of a luminaire according to claim 16 wherein the measuring a power consumption comprises:

measuring a real power consumption and a power factor; and

storing the real power consumption and the power factor in the database.

18. A luminaire and corresponding data set of luminance characterization information the luminaire comprising:

a ballast coil;

a multi-tap capacitor connected in series with the ballast coil, wherein the multi-tap capacitor has a plurality of tap capacitors integrated into a capacitor housing;

a plurality of switches, wherein each switch is coupled to one of the plurality of tap capacitors for selectively coupling the tap capacitors together to produce a multi-tap capacitance corresponding to a configuration of the plurality of switches; and

a lamp connected in series with the multi-tap capacitor and the ballast coil; and

the data set comprising records pertaining to lumen output measurements of the luminaire, wherein the data set has a plurality of records relating the lumen output measurements to each multi-tap capacitance, wherein each multi-tap capacitance corresponds to one of a set of configurations of the plurality of switches.

19. The luminaire and corresponding data set of claim 18 wherein the multi-tap capacitor comprises a base capacitor integrated into the capacitor housing, wherein the base capacitor has first and second terminals connected, respectively, to a first and a second connector lug, wherein each of the plurality of tap capacitors has a first tap capacitor terminal and a second tap capacitor terminal, wherein the first terminal of the base capacitor and each of the first tap capacitor terminals is connected, respectively, to a corresponding connector pin in a multi-pin connector, and wherein the second tap capacitor terminals are connected to the second terminal and the second connector lug. wherein the multi-tap capacitance is measured between the first and second connector lugs, and can be configured to be equal to the base capacitor value plus values of one or more selected tap capacitors connected in parallel with the base capacitor by the plurality of switches.

20. The luminaire and corresponding data set of claim 19 wherein the multi-tap capacitor has (t) number of tap capacitors, and wherein the t tap capacitors have a capacitance value (C x ) where

C

x

=

⁢

C

⁢

tap_tot

⁢

⁢

(

⁢

2

t

-

x

)

⁢

2

t

-

1

for x equal 1 to t, where C tap — tot has a value equal to the difference between a capacitance value for operating the luminaire at a minimum brightness and a capacitance value for operating the luminaire at a maximum brightness.