WHY TUBE LIGHTS ARE FITTED IN PAIRS IN ENGINE ROOM | STROBOSCOPIC EFFRCT

Ever wondered why sometimes you see the rotors of a helicopter being stationary or rotating slowly in some video clips or a wheel of the vehicle rotating in the opposite direction of actual motion? Well.. the reason behind this is the stroboscopic effect. Let's know what this effect is and its connection with fitting tube lights in pairs.

WHAT IS THE STROBOSCOPIC EFFECT AND HOW IT OCCURS

As the ships use an AC source of either 50Hz or 6oHz, the waveform undergoes zero crossing for 100 or 120 times respectively for a 50 or 60 Hz source as shown in the below illustration.

AC WAVEFORM(2 ZERO CROSSING PER CYCLE)

Thus the light turns off 100 times in a second(referring to 50Hz supply). 

Assuming light was used to illuminate near rotating machinery component with nearly similar RPM or in the multiples of the flicker frequency of light used. Thus relative frequency between the light and the rotating component becomes zero. thus appears to be standstill.

thus the STROBOSCOPIC EFFECT IS a phenomenon where the light falling on the rotating or moving  component causes it to appears to be standstill or moving slow or in a reverse direction due to the optical illusion where the visual perception of the eye does not stop even after the light reflecting the object stops.

Dangers due to stroboscopic effect

1. Due to the illusion of the component appearing to be stationary, the operator may meet with an accident.

2. also the flicker may lead to severe headaches.

How to overcome this effect?

zero crossing of different for different phases 

two lights connected to different phases     

    

       

Using two fluorescent lights with supplies from different phases is the best method to overcome this where the source is AC.

since the zero crossing for both the waveforms are different for different lights thus the lamps won't flicker at the same time thus reducing the effect.