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In visual perception, flicker is a human-visible change in luminance of an illuminated surface or light source which can be due to fluctuations of the light source itself, or due to external causes such as due to rapid fluctuations in the voltage of the power supply (power-line flicker) or incompatibility with an external dimmer.
The requirements of a flicker measurement equipment are defined in the international electro-technical standard IEC 61000-4-15. [2]A flickermeter is composed of several function blocks which simulate a 230 V/60 W or a 120 V/60 W incandescent lamp (reference lamp) and the human perception system (eye-brain model).
An unregulated DC supply will produce a lower output voltage. The output voltage ripple will decrease in line with the usually reduced load current. In a cathode-ray tube television, the reduced output voltage will make the screen image smaller, dimmer and fuzzier.
Lights flickered, a subway line was disrupted and some elevators and escalators briefly stopped running when a small explosion at an electrical facility caused a momentary power outage in New York ...
The lights flicker and the analog dials spin back up as emergency power comes online. For everyone working on site — including the senior leadership team — safety is personal. Should something ...
This effect is eliminated by paired lamps operating on a lead-lag ballast. Unlike a true strobe lamp, the light level drops in appreciable time and so substantial "blurring" of the moving part would be evident. Fluorescent lamps may produce flicker at the power supply frequency (50 or 60 Hz), which is noticeable by more people.
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New lighting systems have not used magnetic ballasts since the turn of the century, however some older installations still remain. Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz (twice of the utility frequency; the lamp is lit on both the positive and negative half-wave of a cycle).