Light intensity behavior of LED lamps within the thermal stabilization period

Abstract

Visible changes in the light intensity of lamps, referred to as flicker, are quantified based on definitions such as normalized gain factor and relative light intensity variation. However, those values also change depending on the time after an LED lamp has been switched on. An experiment has been carried out to analyze this phenomenon. A new metric, a "thermal stabilization time", has been proposed to identify the time to reach steady state light intensity. Although rare, the change in light intensity can reach up to 68% during the thermal stabilization time. Consequently, acquiring data at different intervals can lead to incorrect estimation of critical metrics. Stabilization is an essential factor that should be taken into consideration in LED lamps' measurement. It is recommended by the authors that 60-minute operation is required before acquiring data.

Uncertainties in the Quantification of Supraharmonic Emission: Variations over Time

“…4. The fundamental current decreases rapidly during the first 20 min of operation and stabilizes around 60 min following the trend experienced by the light intensity and the temperature reported in [4] and [5], respectively.…”

“…1b. Detailed information about the amplifier configuration can be found in [4]. The lamp shadowed in blue in Fig.…”

“…A clear explanation of the concept of thermal stabilization time can be found in [4]. The thermal stabilization time of the lamp under study has been investigated in [4], [5] from different approaches. The lamp in Fig.…”

“…In summary, the lowest time value, , for which (1) holds defines the thermal stabilization time, . The difference between the criteria in [4] and [5] is summarized in Table I. The thermal stabilization time of the lamp under study (Fig.…”

“…The thermal stabilization time of the lamp under study (Fig. 1a) is then reported as 60 and 70 minutes in [4] and [5], respectively, when supplied with sinusoidal voltage. The RMS value of the fundamental current of every tested lamp during the first 110 min of operation is plotted in Fig.…”