Optimization of the Calibration Interval of a Luminous Flux Measurement System in HID and SSL Lamps Using a Gray Model Approximation

Public lighting systems base their efficiency on the correct measurement of the photometric properties of lamps and luminaires. Metrological traceability, given by external calibrations, is essential to guarantee confidence in the test results. Maintaining traceability implies periodically calibrating the measuring equipment. This work presents a proposal for optimizing the calibration intervals of the equipment used in the measurement of total luminous flux according to IES LM 78 and IES LM 51 for HID and IES LM 79 for SSL lamps. The theory of first-order gray models is applied to estimate the time intervals in which the equipment will go out of tolerance. A methodology is presented to use historical calibration certificates in non-symmetric intervals and calculate points of symmetric intervals to represent the equipment behavior. Additionally, an experimental scheme for a whole system is presented, by weighing each piece of equipment and its relevance in the test of HID and SSL lamps. Finally, the methodology is applied in the lighting laboratory of IIGE with its calibration certificates and the results and advantages are discussed.