Flicker causes disturbance and can cause physiological effects such as headaches. Stroboscopic effects can lead to dangerous situations by changing the perception of rotating or moving machine parts. Lighting systems should be designed in a way that avoids flicker and stroboscopic effects.
Flicker and stroboscopic effects
When using LED luminaires, it is important to consider that while LEDs are usually operated with stabilised direct-current voltage, dimmed operation is often realised using pulse-width modulation (PWM, see also chapter 188.8.131.52, "Dimming with operating current regulation and pulse-width modulation"). The PWM frequency should be higher than 400 Hz for high-quality LED luminaires to reliably avoid negative physiological effects. In industrial plants, danger arising from stroboscopic effects may require separate considerations.
In LED retrofit lamps, costly direct-current generation for LED supply is often passed on. The consequence is pronounced 100 Hz flicker, which may lead to the impairments mentioned above.
Flicker and stroboscopic effects which may occur during discharge lamp operation can be avoided by combining them with electronic control gear (ECG). For low-pressure discharge lamps (fluorescent lamps and compact fluorescent lamps), ECG are the current standard for new installations, which solves the issue of flicker.
Stroboscopic effects can be avoided by using halide lamps with direct-current voltage supply or by operating them with high supply voltage frequencies (ca. 30 kHz).