Sensitivity of modern lighting technologies at varying flicker severity levels

Efficient lighting technologies are not necessarily less sensitive to voltage fluctuations than the incandescent lamp, and therefore a procedure for controlling the immunity of lamps to voltage fluctuations was defined in the IEC 61547 standard. This procedure checks that a lamp is not more sensitive than the incandescent lamp to voltage fluctuations corresponding to the Pst=1 curve. For a lamp that behaves linearly, these tests are sufficient to guarantee that a lamp is less sensitive than the incandescent lamp at any voltage fluctuation level. This paper analyzes the linearity in the response of a set of lamps with both simulated and real voltage signals. For a given input voltage signal containing fluctuations, a new signal was generated with a voltage fluctuation whose amplitude was proportional to the original one. Both signals were passed through an illuminance flickermeter and the obtained flicker severity values were compared. The results showed that not all the lamps behaved linearly. Some lamps were less sensitive than the incandescent lamp at the reference level, and with other voltage fluctuation amplitudes produced flicker severity values higher than the incandescent lamp. Moreover, the nonlinearity shown with real voltage signals was not reflected with the same nonlinear behavior with simulated fluctuations in all cases. These results lead to the conclusion that the current immunity protocol is insufficient for guaranteeing that a lamp is less sensitive to voltage fluctuations than the incandescent lamp at every voltage fluctuation level.