Ripple factor. Pulsation, flickering of LED lamps: the reason and ways to deal with it
Almost 90 percent of the information our brain receives through the organs of sight. It is clear that for a better perception of information, we need good lighting. Our body perfectly perceives natural light. But, unfortunately, we (like our ancestors) cannot afford to go to bed at sunset. Therefore, we have to constantly use artificial lighting in the room. Naturally, such lighting has a number of drawbacks, compared to natural. One of which can be safely called is the pulsation (flickering, blinking, blinking) of lamps. Today we will try to deal with such a concept as a pulsation (flickering, blinking, blinking) of LED lamps. At all. increased ripple of the lamp occurs due to periodic fluctuations in the level of luminous flux, which we receive from any lamp, including the LED.
Light pulsation - This is one of the characteristics of artificial lighting, showing the frequency of flicker of light.
Sanitary standards and regulations require maximum levels of pulsation for each type of lighting. According to SP 52.13330.2011, the ripple is allowed in the range of 10-20 percent. In residential areas, such requirements do not apply.
Most likely because of this, all the boxes of LED lamps simply do not indicate the ripple factor. And in vain ... As we will find out later, very vain ...
Real ripple rates of LED devices
We know what can be both from constant and alternating voltage. And this means that the level (coefficient) of pulsation, flickering, blinking of any LED lamps will be a complete repetition of the level of pulsations of their power sources.
If the lamp is powered by DC, then the luminous flux. emanating from it will be constant, which in itself means a zero coefficient of pulsation.
But in our homes there is no constant voltage. Therefore, depending on the power supply of LED lamps, the ripple will be from 1 to 30 percent.
Often there is a ripple in the LED lamps appearing after. Not often, but this problem also has a place to be.
For comparison, for the time of the measurements, the following figures were obtained:
Pulsation coefficient for induction lamps is not more than 5%.
- for incandescent lamps (halogen) - no more than 5%
- fluorescent from 5-40%
- LED from 1-30%
We see that the ripple factor (blinking, flickering, blinking) of LED lamps can cover the entire range of ripples, depending on the type of power supply used.
Therefore, it can be understood that it is necessary to fight and reduce pulsation to a minimum. So what is harmful pulsation?
The hazard of pulsation (flicker, blinking) LED lamps
We can record the change in incoming information up to 300 Hz. Visually, we do not feel them, but at the subconscious level everything is BAD. As a rule, a person begins to feel bad, there is discomfort, fatigue, dizziness. And it is good if you come across such a pulsation not for long. But if you constantly have such lighting at your workplace, then this will (sooner or later) cause permanent suppression, insomnia, cardiovascular and possibly (not yet proven. But research is being conducted) oncological diseases.
It is also worth noting that such an important and dangerous state of LED lamps is a stroboscopic effect. This is a proven and dangerous fact.It needs to be “cleaned up” from workplaces as quickly as possible. An example of a stroboscopic effect: the frequency of flickering of the lamp coincides with the frequency of rotation of the part on any machine. From this, it seems that the parts on the machines “spin-spin” very slowly. Because of this effect, more than one hundred workers were injured, crippled, and more than one hundred died.
Therefore, the optimal ripple rate of ANY light source should be considered up to 5%.
Comparison of some lamps in terms of pulsation (flicker, blink)
Below are the graphs of the tested lamps by the ripple factor:
1. Incandescent lamp 60 W - 18% pulsation
2. LED lamp Armstrong - ripple 41%
3. Fluorescent lamp 9 W WalSun - ripple 31%
4. Camelion fluorescent lamp - 4% pulsation
5. Fluorescent lamp LB40 - 25% pulsation
6. Lamp LED Philips 9 W - ripple 3.2%
7. LED corn lamp "Chinese" - ripple 68%
According to the data obtained, it is easy to understand that the LED lamp does not give us reason to consider a low ripple. The best factor can be considered a Philips LED lamp. This is not surprising. The more expensive the lamp, the better the brand, the better the pulsation coefficients.Conversely, the widespread use of well-known light sources (Armstrong) does not mean that you will receive high-quality lighting.
After all, before buying, you should ask the seller for certificates for the lamps and accessories (if the light source is going to be "on your lap"). Only then can you be sure that you will not get a negative impact from the pulsation.
Video review comparison of the pulsation of various lamps
In this video you will see a series of comparisons of tests on illumination and ripple on a number of lamps: from incandescent lamps to LED.
Is it possible to cope with the flashing of LED lamps
It is rather simple to cope with blinking, but only for those who understand where and what to do. As a rule, without a soldering iron here is not enough.
All Chinese models do not have drivers in their lamps. so here the problem is solved only with the installation of the driver. But here it is necessary to understand that it must also be found of such dimensions in order to install it in the lamp.
You can try to install a capacitor. In addition to a soldering iron, it is necessary to be able to count. Each lamp has its own. There is no way to do without measurements in order to choose the right capacitor.
All methods are reduced only to the replacement or installation of normal drivers. But again ... These are additional expenses and labor costs. Miser pays twice! Therefore, do not skimp and buy. The pulsation will be there, but the minimum that absolutely suits us.
For those who want to remove the pulsation (blinking, flickering) on their own, there is a good help - "LEDlamps .how to remove pulsation Author: Team Publisher: Russia Year of publication: 2015 Language: Russian Format: Mp4 Quality: excellent Size: 408.20 MB ". Hammer in a search engine and you will succeed.
How to determine the ripple (blinking, flickering) of LED lamps
One of the easiest ways to determine if there is a ripple in your lamp is to use a video camera. Modern cameras in phones have a parameter - quenching the flicker of 50 or 60 Hz. You need to find this option in the parameters and enable it. After that, bringing the camera to the lamp, you can see the flickering (with nothing to confuse it). If the picture remains clear - congratulations, flicker in your lamp or not, or it is negligible.
You can also determine the flicker with the ease of the phone and photos. It is enough to take a photo of the lamp without illumination. The photo will show you whether or not there is a ripple.If you see horizontal darkened stripes on the photo, then you are out of luck ...
More serious methods - using a computer, photo a, resistor, we will not consider. There is a lot of material on this subject in the network Search, yes obnashchite.
We briefly remembered the history of artificial lighting, and also talked a little about what the main parameters are in energy-saving lamps in general and LED lamps in particular. Today, as promised, we will move on to measurements and comparisons (however, so far without unwinding).
Is it worth it?First of all, I was worried about the obvious question - nevertheless, is ordinary LED lamps, which can be bought in a store, in real conditions, so fabulously effective? To answer it, I decided to measure the illumination created in my room by different bulbs, screwed into the same (my) chandelier. Initially, there were three twenty-ovative ELL CFLs in it; for comparison, I took three 12-watt Gauss LED lamps (claimed to be an analogue of a 100 watt incandescent lamp) and, for the purity of the experiment, three ordinary incandescent bulbs of 95 watts each. The measurements were carried out in the center of the room, that is exactly where the brightness of the lighting is most interesting and necessary for me.I will say right away - from the point of view of photometry, this is probably not entirely correct; but from the point of view of ordinary life, such a comparison, it seems to me, is of primary interest, since it reflects the behavior of a light bulb not in the integrating sphere, but in the ordinary chandelier.
The measurements were carried out with a luxometer Mastech MS6610. I eliminated outside illumination with thick curtains (with the lights turned off, the device showed zero lux). Since the luminous flux of fluorescent and LED lamps depends on their temperature, the luminance values were taken twice - immediately after switching on and after a ten-minute warm-up (it was empirically found that after ten minutes of operation the illumination changes very little). Of course, incandescent bulbs do not need to warm up, so for them the measurement was carried out only once, immediately after switching on, so as not to spoil the chandelier, designed, if memory serves me, up to 40 watts (for an incandescent lamp) in each horn. The results of this experiment can be observed in the table below.
Well, it is clear that this test LED lamps (at least those that I had) really surpass everything that can now be screwed into a regular E27 cartridge (with the exception, perhaps, of some exotics).With incandescent lamps everything is clear - I already guessed that the result would not be very impressive. It is more interesting to compare LED lamps and still popular CFLs.
Immediately striking that in the first ten minutes of the CFL brightness change almost five times. In practice, this means that for the domestic scenario “I went into the room (storage room) for two minutes to find something,” they are the worst of all - by the time they reach the operating mode, they will most likely be turned off. This is in addition to the fact that gas-discharge lamps and so poorly tolerate frequent inclusions, although, let's say, in the closet, they may not be so frequent, but, nevertheless, short. LED lamps, on the contrary, somewhat dim the brightness as it warms up - the voltage drop, and, consequently, the power (at constant current) on the heated LED is less. However, the difference in brightness here is not as stunning as in the case of CFLs (which indirectly indicates a fairly good heat sink specifically in these lamps). By the way, it can be seen that after warming up, the difference is still in favor of the LEDs, although its size is such that the illumination created by those and others can be considered approximately equal.However, we are talking about a roughly equal illumination created by a twenty-watt CFL and a twelve-watt LED-lamp - almost twice the power savings. You can not even talk about incandescent lamps - with many times more power consumption due to the created illumination, they lose both CFLs and LEDs. In addition, as I mentioned above, ninety-five watt lamps cannot be screwed into my chandelier at all, so in reality with incandescent lamps I would not even get these hundred lux. Of course, such a limitation is associated with heating.
Incandescent bulbs, obviously, have gone the distance, so let's compare the CFL and LED heating lamp.
These images were also taken after a ten-minute warm-up. It can be seen that the CFL heats up to one hundred degrees or more, while the maximum temperature of the LED lamp is only about sixty. That is, the opportunity to get burned about CFLs, in principle, exists (the protein begins to collapse at eighty degrees Celsius), while with an LED lamp it is impossible in principle. Trifle, but nice.
More measurementsSo, we figured out that in terms of the characteristics that come to mind first, the LEDs are clearly better.Time to talk about more subtle matters such as power factor and ripple factor. For some reason, they rarely remember these hackery, and, of course, they (for the time being?) Are never written on their packages, but in vain.
The ripple factor is a very important indicator. Despite the fact that changes in brightness with a frequency of more than 16 - 20 Hz, our brain consciously does not process, the effect of them is quite noticeable. Significant pulsations of general illumination can lead to fatigue, migraines, depressions and other unpleasant things in terms of the psyche. This indicator is normalized in SNiP 23-05-95. There are a lot of different tables, but, in general, from them it can be taken out that the ripple factor of the general illumination should not exceed 20%. It is worth making a reservation that talking about all this makes sense up to a frequency of about 300 Hz, because the retina itself no longer has time to react to changes in illumination, and therefore in this case an irritating signal simply does not come to the brain.
The power factor for the end user, in principle, is unimportant. This parameter shows the ratio of the active power consumed by the device to the total power that takes into account the reactive part, which does not produce useful work, but, in particular, the heating wire.Also common is the name “cosine phi” - this is all because the quantity of interest to us can be entered as the cosine of some conventional angle. The maximum, ideal value of the power factor is 1. Household meters take into account only active power, they write it on packages; for the consumer in this sense, there is no problem. However, if we are talking about global scale (for example, a millionth city entirely illuminated by LED lamps), a low power factor can create big problems for power engineers. Therefore, its rating is the rating of the lamp in the sense of a bright LED future.
I measured the power and power factor with the muRata ACM20-2-AC1-R-C head. The ripple factor was measured with an Uni-Trend UTD2052CL oscilloscope, to which the following circuit was connected:
To whom it is interesting, this is a classic frequency-compensated “current-voltage” converter on the operational amplifier, supplemented with an artificial midpoint. It feeds, to eliminate interference, from the battery. The BPW21R diode is a photometric class device with a characteristic compensated according to the sensitivity of the human eye.The documentation guarantees the linearity of the current depending on the illumination in the photovoltaic mode, so that the circuit produces a voltage directly proportional to the illumination of the photodiode and is quite suitable for measuring the ripple factor. It is determined, by the way, as the ratio of the range of pulsations to twice the average value. Both the scope and average value are included in the standard automatic measurements of any modern digital oscilloscope, so there is no problem with this - it only remains to double and divide. Comparison of the measurement results of this improvised design with the values given by the TKA-PULSE device (State Register) showed that the measured pulsation coefficient did not exceed one percent.
So, the results of measurements for the lamps that were at my fingertips:
With E27 socket:
With E14 socket:
About the lamp Wolta should talk separately
On the package we read the proud inscription:
“Optimal flicker frequency for eyes.” To go nuts! What is the frequency there? Maybe they mean that it is far beyond the three hundred Hertz regulated by sanitary standards?
On the oscilloscope we see:
100 Hz, ripple factor 68%. According to SanPiN does not pass. What they understand as optimality is a mystery ...
As we see, here at LED lamps not everything is so rosy. Immediately it turns out very interesting fact - it seems that the quality of LED lamps can not be judged only by the manufacturer; the same brands, generally speaking, set both quality records and anti-records. It should be noted that I passed the general verdict presented in the table, giving greater importance to the ripple coefficient than to the power factor, for the reasons stated above. But even the ripple factor of 1% cannot fully justify a power factor of 0.5 in the case of an industrial product sold in millions of copies. However, for the home it is better to take such a lamp than a product with a unit power factor and a ripple level of 50%.
Of course, lamps with a ripple factor of more than 20% are categorically not suitable for general lighting (there is no need to twist it into a six-piece chandelier). By the way, for the “Era” CFLs mentioned by me, it is slightly less than 10%, and for the classic incandescent lamp - about 13%.
The last parameters that can be casually discussed are the color temperature and the color rendering index.Despite the fact that they are formalized, at the household level it all comes down to “like / dislike”. I must say that all the lamps tested in this regard pleased me - none of them had a clear bias or excessive yellowness, all had a pleasant white tint. But this, of course, for my taste, and nothing more.
In the following articles, we will finally see what's inside the lamps, and try to figure out which internal causes make good lamps good and bad ones bad.
Note:The choice of lamps for tests is determined solely by the consideration of what was. If (when) other lamps appear, I measure and lay out.
One of the most important physical factors in every workplace is lighting. Lighting not only makes it possible to perform work, but also ensures the level of productivity and quality of work, injury safety and the state of health of workers. Monitoring and evaluation of lighting conditions for certification of workplaces is carried out in accordance with the requirements of R 2.2.2006–05 “Guidelines for hygienic assessment of factors of the working environment and the work process. Criteria and classification of working conditions "according to the method described in MU OT RM 01-98 / 188.8.131.526-98" Evaluation of workplace lighting. "At the same time, the illumination is estimated by parameters that characterize both the quantity and the quality of light. Among the indicators of the quality of light, a special place is occupied by the pulsation of illumination. This parameter of the light environment invariably raises questions.
Analysis of the results of certification of workplaces with personal computers shows that most of them are “conditionally certified” due to non-compliance with the requirements of the norms on limiting the depth of pulsation of light. And often new lighting installations, often made with imported lamps, having a modern design and providing a sufficient amount of light, often do not meet the requirements of the norms for limiting pulsation. As a result, externally spectacular lighting systems do not meet the requirements for the quality of lighting and turn out to be harmful in terms of conditions and labor protection. The use of four-lamp raster mirror lamps in administrative premises also often leads to a violation of the requirements of the rules for the pulsation of illumination. At the same time providing the required levels of illumination is not a problem.
At high levels of illumination, the assessment of lighting conditions as harmful causes confusion among employers: there is a lot of light, whence can there be “harmfulness”? However, this “harmfulness” is very clearly noted by those working in conditions of increased pulsation, who, without fixing it visually, express an unwillingness to work “under fluorescent lamps”. This problem is not new, and according to G. M. Knorring, an outstanding lighting designer, “in the first years of using fluorescent lamps, when the harm of pulsations was underestimated and measures were not taken to restrict them, otherwise the lighting installations were otherwise compromised. for pulsations. "
What is the ripple light? Among the indicators of the quality of the light environment, this is perhaps the most "cunning" parameter. The treachery of the pulsation of the luminous flux is that the eye does not feel the vibrations of the light, but the brain reacts negatively to them, and the person does not understand why he is very tired and does not feel well.
The cause of the illumination pulsation is the alternating current feeding the lighting installations. The luminous flux of light sources when powered by an alternating current of industrial frequency of 50 Hz pulses at twice the frequency of 100 Hz (see figure).
This phenomenon is most characteristic of gas-discharge light sources. The process of electrical discharge in these lamps is practically non-intrusive and follows the frequency of the alternating current, and therefore, the emission of the phosphor, which has only a low afterglow, is also variable in time. It should be noted that the pulsation of illumination is also observed in lighting installations with incandescent lamps; it is very insignificant when using high-power lamps (3-5% with lamps of 300-500 W), but with a decrease in power to 100-60 W it can reach 11-18 %
The pulsation of the luminous flux is not perceived visually, since the frequency of pulsations of 100 Hz exceeds the critical frequency of fusion of light flashes. Electrophysiological studies have shown that pulsation adversely affects the bioelectric activity of the brain, causing increased fatigue. This is due to a change in the basic rhythmic activity of the nerve elements of the brain, rebuilding their inherent frequency in accordance with the frequency of the light pulsation.
The negative impact of the ripple increases with increasing depth.Most researchers note the negative effect of light pulsation on human performance both during prolonged exposure to pulsed illumination and during short-term exposure for 15–30 minutes. This determines the requirements for limiting the depth of pulsation of the light flux in lighting installations.
Since the main quantitative parameter of lighting installations is the normalized level of illumination, as a criterion for estimating the depth of light fluctuations in lighting installations powered by alternating current, the coefficient of illumination of the illumination on the working surface, characterizing its depth, was adopted. It is equal to the ratio of half of the maximum difference in illumination over a period of fluctuation to the average illumination over a period, expressed as a percentage.
It has been established experimentally that the negative effect of pulsation on the human body is sufficiently small only at a pulsation depth of no more than 5–6% at a frequency of 100 Hz. With a light oscillation frequency of 300 Hz and more, the depth of the pulsations does not matter, since the brain does not respond to this frequency.
When working with VDT on cathode-ray tubes, the question of limiting the pulsation of illumination is particularly acute,since the human brain reacts extremely negatively to two or more simultaneous, but different in frequency and non-multiple rhythms of light stimuli. This is the situation when working on a personal computer. Therefore, to lighting installations in rooms with computers are very stringent requirements for the pulsation of illumination - no more than 5%.
Limiting the pulsation of illumination is required not only in rooms with computers, but also in the performance of other types of work, especially work related to exact. In this case, particular attention should be paid to the system of combined lighting, where the pulsation should be limited not only in local lighting (as a rule, for this purpose, lamps with incandescent lamps are used), but also in general. There is reason to believe that peripheral vision is especially sensitive to pulsation, therefore, general illumination must also meet regulatory requirements (no more than 20%). In practice, often the general illumination of mechanical shops, made with lamps with high-pressure discharge lamps (DRL, DNaT) without distribution over the network phases, creates a pulsation of illumination reaching 80-90%.
It should be noted that the presence of pulsations of illumination that exceed regulatory requirements, can cause a so-called stroboscopic effect, that is, the phenomenon when fast moving objects appear progressively to have multiple outlines. Rotating objects, depending on their speed of rotation, may seem to have stopped, changing the speed or direction of rotation. Distortion of visual perception of rotating, moving or changing objects in flickering light, which occurs when the frequency characteristics of the movement of objects coincide or are multiplied and the luminous flux changes with time, can be a direct cause of injury.
Measures to limit the depth of the pulsation of light are well developed. They are set forth in any reference literature on lighting engineering (“Reference book on lighting engineering” edited by Yu.B. Aizenberg, “Reference book for the design of electric lighting”, edited by G.M. Knorring, etc.). The requirement for the mandatory assessment of the coefficient of pulsation of illumination is set out in R 2.2.2006-05 "Guidelines for the hygienic assessment of factors of the working environment andlabor process. Criteria and classification of working conditions ”and in the Guidelines“ Evaluation of workplace lighting ”. Control of the pulsation coefficient of illumination is currently performed instrumentally using instruments.
All sectoral and departmental regulatory documents on lighting contain normalized values of the pulsation coefficient, and their requirements should be taken into account when designing lighting installations (OA). In addition, GOST 17677-82 "Lamps. General technical conditions ”also contains requirements for limiting pulsation, in particular, it is indicated that in luminaires with a number of lamps multiple to two, control gears should be used to ensure the phase shift between the lamp currents (see Section 3.2.3 of GOST). And the requirements of this GOST must be complied with.
Theoretically, all of our existing lighting installations should ensure the proper quality of lighting. Moreover, the practical support of the requirements of standards for limiting the depth of the pulsation of illumination is technically achievable: the use of the most suitable for this type of work light sources, ballast with a “split phase”, the inclusion of lamps on different network phases, if necessary, the use of VCHPRA ..However, as shown by the results of the survey of illumination, almost all existing lighting installations at workplaces with computers do not provide a normalized pulsation depth of illumination and, as a rule, it is 28-35%, and sometimes reaches 41-50%.
Solutions that comply with regulatory requirements for lighting (both in quantity and quality) should be provided at the design stage. Unfortunately, the design level of lighting installations currently leaves much to be desired. In addition, during certification of luminaires, the pulsation coefficient of the illumination is not checked. The situation is complicated by the fact that most of the domestic manufacturers of luminaires do not comply with the requirements of GOST 16677-82 in terms of limiting the depth of the pulsation of illumination. Often, lighting installations in offices where there are workplaces with computers are mounted without projects at all, just someone liked the lamps in a nearby institution, they decided not to install three, but, for example, four such lamps — so that it was lighter! And if the order of installation of lighting installations is not observed, then what quality of lighting can we talk about.By the way, competent designing of lighting in rooms with computers is a difficult task, technical decisions sometimes have to be taken at the level of a compromise, only an experienced lighting technician can handle this task.
In fairness it should be noted that recently the lighting has finally been noticed. Many employers have the intention to bring the lighting systems in a state that meets the requirements of the standards, including the pulsation coefficient of the illumination. Many of them are faced with the problem of the lack of information about the possibility of acquiring the appropriate high-quality equipment, and this is at a time when any manufacturer is looking for markets and is ready to offer its products.
Unfortunately, in order to ensure the required standards for the pulsation of illumination, it is often necessary today to reconstruct existing operating installations. However, this process should not be allowed to take its course. The modern lighting market is filled with both cheap low-quality products and high-level products, but expensive.In order to reasonably choose the “middle ground”, it is impossible to do without specialists who are familiar with lighting issues.
It is necessary to once again pay attention to the need for high-quality design of newly created lighting installations; it is unacceptable to install lighting systems without appropriate projects. It is necessary to take a more responsible approach to the process of acceptance of lighting installations into operation, and to carry out production control in full compliance with the requirements of regulatory documentation. The issue of information should be resolved: consumers need to know what they need and where to buy it, and manufacturers need to provide information about their products in full, and in a form that is accessible and understandable to buyers.
Unfortunately, it is very difficult to get information about the lamps sold. Sellers assert that there is a certificate for the lamp, indicating that the lamp in the passport for compliance with the requirements of GOST (as a rule, these are GOST requirements for fire safety). There are no instructions on the types of installed ballasts in the passport. That is, you need to be very good at how to ask an interesting question about the limitation of the ripple coefficient in order to get an adequate answer.
As for the reconstruction of existing lighting installations, the most appropriate solution to this problem is the development of standard recommendations with the assistance of competent specialists - lighting engineers.