There are two types of light engines in the market now, one is an electrolytically capacitorless light engine with high PF but serious flickering, and the other is an electrolytically capacitor light engine with no flickering but low PF. So which light engine is better?
First, the origin of the problem
Now there are two kinds of light engines in the market, one is an electrolytic capacitorless light engine with high PF but serious flicker, and the other is an electrolytic capacitor light engine with no flicker but low PF. So which one is better?
Second, the cause
A Silicon Valley company ExClara invented an LED system, to improve the power factor PF, not only by taking out the electrolytic capacitors, but to make the current waveform and voltage waveform exactly match, using the LED string divided into several groups and sequential conduction. The result of this must be to cause the LED to intermittently light and produce serious flicker.
Third, the degree of flicker
LED was originally required to have a certain start-up voltage (2V or more) to conduct, and now wait for the input voltage to rise to a certain height before conduction, which will inevitably make in the middle of the two half-sinusoidal waveforms there is a very large dark area (see the arrow area below), which makes it flicker far more than other lamps (such as incandescent, fluorescent lamps) to be much more serious.
Fourth, the consequences and problems caused by flicker
1. The impact on the human body:
-Can produce strain fatigue, blurred vision, and the traditional headache; -Can produce strain fatigue, blurred vision, and the traditional headache.
-Causes seizures in photosensitive epileptics; -Increases in autistic children.
-Increases repetitive behaviors among autistic children.
2. Effects on production workers
For workers who require vision and vision-related workers can to a decrease in operational performance.
-For workers who use or come into contact with rotating machinery, it can have the effect of slowing down, stopping, or even reversing the rotation, which can to serious workplace accidents.
3. Impact on video, TV, and movie production
The flickering of lights has a bad effect on the production quality of movies and TV dramas, with ghosting and interference streaks, which make it impossible to play.
4. Impact on security, warning system
Because the camera's camera moment may happen to be in the light of darkness, it is possible to shoot a black image, that is, the loss of a complete frame. If this frame happens to be the mob murder moment, then a piece of important evidence is lost!
Fifth, how to eliminate flicker
The thorough approach is to eliminate the root cause of this brightness flicker. That is the rectifier after the use of electrolytic capacitor filtering, completely filters out this AC ripple.
After the use of electrolytic capacitor filtering, the rectified sinusoidal waveform is smoothed to become close to the DC waveform, there is only a small ripple, and the larger the capacity of the electrolytic capacitor, the smaller the ripple. In other words, the flicker is eliminated.
Six, the use of electrolytic capacitors "shortcomings" - PF low
Why these "shortcomings" with quotes? Because this test result is measured with the market problematic power factor meter! And the results of these power factor meters are very doubtful.
For example, we use the same electrolytic capacitors of the 102W LED light engine system, using different test instruments to test the results as follows: the market commonly used digital power factor tester measured a power factor of 0.6590. But if we use the national CHNT recognized Cosφ meter to test the same system, but can get PF = 0.9 results. It can be seen that the test results of this digital power factor meter are very problematic.
So what exactly is the power factor?
Power factor is originally a linear AC electrical system in the cosφ, that is, the voltage sine wave and current sine wave between the angle of the cosine value, which represents the voltage and the voltage is different from the phase of the current sine wave projected onto the direction of the voltage vector. Or it is the value of the component of the current vector that is in phase with the voltage vector. Multiplying this in-phase value by the voltage is the active power. Multiplying two two components the voltage vector is the reactive power. If cosφ = 1, that is, PF = 1, then there is no reactive power. The reason for defining a cosφ as the power factor in a linear AC system is to be able to compensate by employing another device with an opposite phase angle to zero reactive power.
However, in a nonlinear system that employs a rectifier, the current wave is not sinusoidal at all, so there is no way to know what its cosφ is equal to. That is, it is not known how PF should be defined. Internationally, there are 4 different definitions. But strangely enough, there are power factor measurements for nonlinear systems available on the market today.
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