Photosensor and control system for dimming lighting fixtures to reduce power consumption

A lighting control system for providing desirable illumination at a task location while saving power, the system comprising:

• at least one lighting fixture having a control ballast and producing controlled electric light with an intensity responsive to a control signal provided to the control ballast;
• and
• a photosensor which generates the control signal, the photosensor including:
• a self-powered wireless photocell unit having a photocell for generating a sensor signal responsive to the illumination level and a wireless to transmitter for transmitting the sensor signal, and
• an interface control unit wired to AC power and the lighting fixture and adapted for receiving the sensor signal and providing the control signal to the lighting fixture;
• wherein the control signal is responsive to illumination measured by the photocell, differences in the ratios of illumination at the task location to an operational sensor location for uncontrolled light and controlled electric light, and a user preference.

A method for commissioning a photosensor for use in a lighting control system comprising the steps of:

• (a) providing a photosensor including a self-powered wireless photocell unit configured to be movably positioned for commissioning and a digital processing unit;
• (b) positioning the photocell unit at a task location;
• (c) initiating a commissioning procedure programmed in the processing unit, wherein the photosensor measures a combined uncontrolled light and controlled electric light illumination level at the task location, turns off an electrical lighting fixture providing the controlled electric light, measures an uncontrolled light illumination level at the task location, turns on the electrical lighting fixture, and prompts an operator to move the photocell unit;
• (d) positioning the photocell unit at an operational sensor location;
• and
• (e) continuing the commissioning procedure, wherein the photosensor measures a combined uncontrolled light and controlled electric light illumination level at the operational sensor location, turns off the electrical lighting fixture, measures the uncontrolled light illumination level at the operational sensor location, turns on the electrical lighting fixture, and calculates set-points for an illumination control algorithm using the measured illumination levels.

A method for commissioning a photosensor for use in a lighting control system, the method comprising the steps of:

• (a) measuring a combined uncontrolled light and controlled electric light illumination level at a task location;
• (b) turning off an electrical lighting fixture providing the controlled electric light;
• (c) measuring an uncontrolled light illumination level at the task location;
• (d) turning on the electrical lighting fixture;
• (e) prompting an operator to move a photocell unit;
• (f) measuring a combined uncontrolled light and controlled electric light illumination level at an operational sensor location;
• (g) turning off the electrical lighting fixture;
• (h) measuring an uncontrolled light illumination level at the operational sensor location;
• (i) turning on the electrical lighting fixture;
• and
• (j) calculating a set-point and ratios for an illumination control algorithm using the measured illumination levels.

A machine-readable medium having encoded on the medium a program code, wherein, when the program code is executed by a machine, the machine implements a method for commissioning a photosensor for use in a lighting control system, the method comprising the steps of:

• (a) measuring a combined uncontrolled light and controlled electric light illumination level at a task location;
• (b) turning off an electrical lighting fixture providing the controlled electric light;
• (c) measuring an uncontrolled light illumination level at the task location;
• (d) turning on the electrical lighting fixture;
• (e) prompting an operator to move a photocell unit;
• (f) measuring a combined uncontrolled light and controlled electric light illumination level at an operational sensor location;
• (g) turning off the electrical lighting fixture;
• (h) measuring an uncontrolled light illumination level at the operational sensor location;
• (i) turning on the electrical lighting fixture;
• and
• (j) calculating a set-point and ratios for an illumination control algorithm using the measured illumination levels.