Stroboscopic Effect in Fluorescent Lamps

Stroboscopic Effect in Fluorescent Lamps

The stroboscopic effect is a phenomenon by virtue of which a running or moving appliance appears to be stationary. Also, due to the stroboscopic effect, the devices may seem to be moving in the opposite direction or look as if they are moving slower than their actual speed of motion. Stroboscopic Effect is generally observed when the environment is illuminated with the help of fluorescent lamps; however, it may occur when tube lights and other ac powered light sources are used.

Explanation of the Stroboscopic Effect

Fluorescent lamps contain fluorescence material that gets excited upon being irradiated by electromagnetic radiation of a particular wavelength and tend to emit out energy in the form of light. The efficiency and life span of fluorescent lamps is approximately three times more than the filament lamps, which is why they are usually preferred for domestic and commercial purposes. These types of lamps are generally provided with a 50-60 Hz ac current supply. While being operated, the number of times that the lamp tends to cross the zero frequency or become zero is equal to twice the frequency of the power supply. This means that if the lamp operates at a supply frequency equal to 50 Hz, it passes the zero instant at least a hundred times. Similarly, a lamp operating at 60 Hz supply frequency tends to cross the zero frequency 120 times. The persistence of vision of a human eye does not allow us to notice and acknowledge the flickering of the light caused when the lamp crosses the zero frequency. When the light from such lamps or light sources falls on the moving parts of the devices, they appear to be moving relatively slower than their actual speed or seem to be moving in the opposite direction. In some cases, the moving parts of the device may also appear to be standing still and not moving at all. This effect is known as the stroboscopic effect. It can occur in both three-phase and single-phase power supplies. A stroboscopic effect is a form of illusion that disrupts the normal view of the moving objects present in the surroundings.

The Wagon-wheel effect: gifs

Dangerous Consequences of the Stroboscopic Effect

The stroboscopic effect appears to be harmless, but it can be dangerous in numerous ways. Some of the real-life examples given below demonstrate the dangerous consequences caused due to the stroboscopic effect:

1. The rapidly moving needle of a sewing machine may appear to be standing still in a place because of the stroboscopic effect of the tube light or a fluorescent lamp present in the room. This may cause severe injury to the user in many ways.

2. The stroboscopic effect may cause the wings of a running machine at a factory or industry to appear to be standing still. If the worker operating the machinery is unaware of this phenomenon, he/she is most likely to get harmed or face serious injuries.

3. The stroboscopic effect causes severe headaches.

4. Due to the ageing of the lamps, the flickering may also occur at 20-70 Hz frequency. The stroboscopic effect caused due to this may also induce epileptic seizures.

5. About 10% of the people working in an area that is exposed to the stroboscopic effect are much likely to develop migraines and other related problems.

6. It tends to cause a significant amount of downfall in the performance.

Measures to Prevent the Stroboscopic Effect

There are certain measures that can be employed to prevent the occurrence of stroboscopic effect given below:

1. Stroboscopic effect occurs at a significantly higher level if the environment is illuminated with the help of a fluorescent lamp. Hence, one must avoid the usage of fluorescent lamps to avoid the stroboscopic effect.

2. If a three-phase power supply is used to power the lamps, then the adjacent lamps must be fed with different phases. This would cause the lamps to undergo zero frequency at different instants. Thereby, minimizing the flickering of lights.

3. If a single-phase power supply is employed to power the lamps, then the connection of the lamps should be made in such a way that the adjacent lamps are in parallel with the power supply.

4. In one lamp connection, a capacitor or condenser can be connected in series with the choke. This creates a phase shift that helps to eliminate the stroboscopic effect.

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