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Is high PF important or no flicker? Which light engine is better?
- Dec 30, 2017 -

Now there are two kinds of light engines in the market, one is high PF but there is a serious twinkle of an electroless photoelectric engine, and the other is a non-flickering and low-pf electroluminescence engine.

So which light engine is better?

The cause of

A silicon valley company ExClara invented a LED system, in order to improve the power factor PF, not only take away the electrolytic capacitor, and in order to make the current waveform and voltage waveform match exactly, the LED string can be divided into several groups and conduction in turn.

The result of this is that LED intermittent luminescence can produce a serious twinkle.

Scintillation degree

LED is needs to have certain starting voltage (above 2 v) to conduction, now have to wait as the input voltage rises to a certain height after conduction, doing so will make in the middle of two and a half sine wave, there is a large dark space (see figure 1 arrow area), making it far more than any other lamps and lanterns of the shining (like incandescent lamp, fluorescent lamp) is much more serious.

4. The consequences and problems of flickering

1. Effects on human body:

It produces strain fatigue, blurred vision, and a traditional headache

It can cause an epileptic seizure

Increase repetitive behaviors among autistic children


2. Impact on production workers

Workers who require vision and vision will lead to lower performance;

Workers who use or contact rotating machines will have an effect of turning slower, stopping, or even reversing, which can lead to work-related accidents.


3. Influence on athletes

For athletes with extremely high speed sports such as table tennis, for every 1/100th of a second, there is a darkness of 2ms, and the flicker of this light often causes errors in the direction of the ball.


4. Influence on literary photography

They leave streaks in the picture

There are flashing


A long exposure to the camera creates a strange face


5. Effects on video, TV and film production

The flicker of the light has a bad effect on the production quality of the movie and TV series, with heavy shadow and interference fringes that can't be played.


6. Impact on security and security system

Because the camera's camera could be just in the dark of the light, it's possible to make a full black image, which is to lose a full frame.

If this frame happens to be the moment of the mob's attack, it loses an important piece of evidence.


5. How can I eliminate the flicker

The easiest way

The most thorough approach is to eliminate the source of this brightness flicker.

That is to apply the electrolytic capacitor filter after the rectification, and thoroughly filter the exchange ripple.

After the electrolytic capacitor filter is used, the sine wave after rectification is basically smoothed into a waveform that is close to dc, with only a small ripple, and the larger the capacitance of the electrolytic capacitor, the smaller the ripple.

In other words, the flicker is basically eliminated.


6. The "defect" of electrolytic capacitance is adopted

Why does this "defect" take quotation marks?

Because the result of this test is to use the power of the problem on the market measure to measure!

The results of these tests are questionable.

For example, we use the same electrolytic capacitor of 102 w LED light engine system, using different test instrument test results are as follows: the commonly used on the market of digital power factor meter measured power factor of 0.6590.

However, if we test the same system using the cosine phi phi of the national CHNT, we can get the result of PF= 0.9.

It can be seen that this digital power factor test result is very problematic.

So what is the power factor?

Power factor was linear cos phi in ac electrical system, is the voltage sine wave and cosine of the Angle between the current sine wave, it represents a different phase and voltage of electric current to the voltage sine wave projection vector direction.

Or the current vector and the phase component of the voltage vector.

You can multiply this by the same phase and the voltage is the active power.

Two or two components and a voltage vector is a reactive power.

If cosine phi is 1, or PF= 1, then there's no reactive power.

In the linear communication system, the reason to define a cosine phi phi as a power factor is to be able to compensate by using the opposite device of another phase Angle, so that its reactive power is zero.

However, in a nonlinear system using the rectifier, the current wave is not a sine wave at all, so it is not known how much cosine phi phi is.

I don't know how PF should be defined.

There are said to be four totally different definitions.

However, it is strange that the power of nonlinear system can be measured in the market.

Just all these digital power factor meter can give the power factor of the positive and negative, because they are using the ratio of the active power and reactive power as the power factor, power is no minus sign, of course, the ratio of the two power also have no a plus or minus.

This definition is obviously problematic, and this topic is now the subject of a master's thesis at an American university and a doctoral thesis at the university of Sweden.

One of the most important features of power factor is that there are positive and negative signs.

Because the power factor is divided into inductive load and capacitive load, sensibility is positive.

Tolerance is negative. They can compensate each other.

The usual home refrigerators, air conditioners, televisions and so on are emotional loads.

Therefore, the electric industry bureau often compensates with a large capacitor in the transformer's secondary parallel.

And the LED power supply and the electrolytic capacitor are obviously capacitive loads, so the compensation for the power factor of the appliance should also be beneficial!

But the digital power factor on the market can't give the sign!

Can be seen from the above description, the electrolysis electric face to the engine's low the power factor of the so-called "shortcomings" is a fundamental problem that unclear, if this kind of problem, for one thing not ulterior motives or at least an extravagance!


7. Small power LED lamps should not have the power factor limit at all

The power factor of small power appliances in the original state is very clear, which is that small power appliances below 75W have no power factor requirements and restrictions.

For the lamps and lanterns of the past also didn't ask for any power factor, such as domestic commonly used 36 w fluorescent lamp is the vast majority of the ballast, the starter inductively coupled with its power factor is also very low, only 0.51 or so.

The country has never said a word to it.

Later high power metal halide lamp, even up to 1000 watts, inductance is also used as ballast, power factor and only 0.51, and is the perceptual load and also no one has to ask for a power factor for it.

Later on, it seems that there are no restrictions on the energy-saving lamps (since almost all the commonly used energy-saving lamps are below 15W, so this requirement also has no meaning!).

It is only when the LED light is made that the requirements are very demanding, and the power factor is not required under 5W.

It is known that the eu usually demands the strictest, while the European Union demands that only 25W or more is required for power factor. Our country's demand is five times higher than that of the eu!

It seems to be trying to spite the domestic LED lamps.


There are many more serious problems with the light engine with no electrolytic capacitance

The biggest problem is that it USES a very inefficient linear source, which is only 85% efficient.

Fifteen percent of the power is turned into heat.

If you use this low-efficiency linear power supply to make a light engine on the aluminum substrate, then you have to have 15% of the heat added to the LED.

Take the light engine that should be 10W.

Remove the 1.5 W power supply, power consumption is only 8.5 W supply LED, had LED the electric - light efficiency is 40%, is had a 8.5 x0.6 = 5.1 W heat, now increased the quantity of heat of 1.5 W, is to increase the 1.5/5.1 = 0.3, equivalent to a 30% increase in the quantity of heat.

That is, the temperature of the LED is increased by 30%.

Normally designed radiators should make the temperature at 85 degrees and now increase to 110 degrees, which will reduce its thermal efficiency by 25 percent and reduce its life span from 30, 000 hours to 10, 000 hours.

The conclusion should now be clear: the advantages of a non-flickering high-performance optical engine are far higher than the serious twinkling light engine of the so-called high PF!

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