Light - important characteristic livability, comfort in the workplace and in living quarters depends on it. Doctors have long noted that the main reasons for vision loss in many people are working conditions; lighting parameters in workplaces are often not well thought out.

In addition, it has been proven that bad light has a negative effect on brain function, causes drowsiness, and leads to decreased performance. Excessive lighting is also not useful, activating the work of the body's auxiliary resources, it leads to accelerated wear and tear of all systems.

Our laboratory measures lighting in workplaces, as well as in residential and non-residential premises, in compliance with all norms and regulations. We work with both individuals and legal entities.

The specialists of the Moscow Disinfection Service offer you their professional assistance in assessing the quality of illumination of the room you are interested in.

We offer:

• Measuring illumination of workplaces;
• Measurement of room illumination;
• Measurement of artificial light.

All work is carried out by experienced specialists who are well acquainted with the technologies of microclimatic research. Measurements are performed using high-tech equipment, which allows obtaining results with minimal error parameters.

The illumination level is measured in accordance with the interstate illumination standard enshrined in GOST 24940-96.
What lighting parameters should specialists measure:
Minimum, average and maximum illumination;
Cylindrical illumination;
Calculate KEO (daylight factor) and KZ (safety factor);
Determine the relative spectral luminous efficiency of monochromatic radiation.

In order for the study to be reliable and accurate, before taking measurements it is necessary to replace all burnt out light bulbs and thoroughly clean the lamps.

The most accurate results are provided by lux meters whose spectral error is no more than 10%.

However, it is possible to measure illumination in an unprepared object, but the results of the study necessarily reflect that the room was not prepared.

Europe also has its own standards for the quality of room lighting, here are some of them:

• 300 lux is the lighting standard for rooms in which employees do not have to examine small details;
• 500 lux is the norm for offices where employees spend most of their working time at the computer;
• 750 lux – for rooms in which technical drawings are drawn up or checked.

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A slight shadow or presence nearby may affect the measurement results. electromagnetic radiation. After the lighting measurements have been completed, the illumination indicators are calculated using special formulas and compared with the standard ones. Based on the results, an evaluation protocol for the facility is drawn up.

"Moscow Disinfection Service": light measurement

Employees of the Moscow Disinfection Service offer legal entities and individual entrepreneurs to measure illumination. We propose to conduct a number of other studies aimed at creating comfortable and safe working conditions at the site.

The problem of measuring illumination from artificial sources

One of the main problems when illumination measurement- this is an impossibility measure the illumination with a luxmeter and pulsations from artificial light sources during daylight hours. Natural light created by windows, transparent light openings, etc. seriously distorts measurement results. The situation is aggravated by the fact that during the day, light openings are a source of light, and at night, as a rule, they absorb it, unlike other surfaces (especially if they are light-colored). Thus, a high value of natural illumination coefficient (NLC) in a room makes it more comfortable…. But! Only during daylight hours. At night, such a room requires additional artificial lighting.
That's why, techniques for measuring illumination and pulsation require measurements to be taken in the absence of natural light. That is, before measuring room illumination it is necessary to densely darken all light openings in it. If this is not possible (for example, buildings with a large glass area), then measuring illumination is allowed only at night. This gives rise to several problems:

• inability to carry out artificial light measurements in northern regions with long daylight hours in summer;
• restrictions on access to enterprises and organizations in the evening and at night;
• the need for measurement laboratory personnel to work at night

How to measure illumination and pulsations during daylight hours.

Measure illumination with a lux meter during daylight hours, it is still possible, if you take into account the fact that the illumination value is additive. That is, the illumination values ​​from all light sources at the measurement point are added up:

$$E = \sum\limits_(i = 1)^N ((E_i))$$

Then, knowing the natural (E amb) and total illumination (E sum) at the measurement point, you can calculate the artificial illumination (E art) using the formula:

$$(E_(art)) = (E_(sum)) - (E_(amb))$$

An example of calculating artificial illumination taking into account the presence of natural light.

However, measure lighting pulsation during daylight hours this method of measurement will not help. The light pulsation coefficient is calculated using the formula:

$$(K_p) = \frac(((E_(\max )) - (E_(\min ))))((2(E_(med)))) = \frac(((E_(\max )) - (E_(\min ))))((2\frac(1)(T)\mathop \smallint \nolimits_0^1 E\left(t \right)dt))$$

Consider the following example. Let us have workplace(RM), illuminated by artificial and natural light sources. Wherein:

• the average total illumination is E sum = 750 lux with a maximum value
  E sum.max =900 lux and minimum - E sum.min =600 lux;
• constant background natural illumination through light openings is E amb = 400 lux;
• in the absence of natural light, the average artificial illumination from lamps is E art = 350 lux with maximum and minimum values, respectively, E art.max = 500 lux and E art. min = 200 lux.

Obviously, during daylight hours, using a regular lux meter, we can only measure the total illumination E sum (with the lamps on) and the natural illumination E amb (with the lamps off). Knowing the values ​​of E sum and E amb, we can calculate the value of artificial illumination E art:

$$(E_(art)) = (E_(sum)) - (E_(amb)) = 750 - 400 = 350\;lx$$

which corresponds to the value of illumination from artificial sources in the absence of natural light.
At the same time, using a regular lux meter-pulse meter we can obtain the pulsation coefficient only for the total illumination, calculated by the formula:

$$(K_(p.sum)) = \frac(((E_(sum.\max )) - (E_(sum.\min ))))((2(E_(sum.med)))) = \frac((900 - 600))((2 \times 750)) = \frac((300))((1500)) = 0.2\;\left((20\% ) \right)$$

However, we need to measure the ripple factor of artificial lighting, which is:

$$(K_(p.art)) = \frac(((E_(art.\max )) - (E_(art.\min ))))((2(E_(art.med)))) = \frac((500 - 200))((2 \times 350)) = \frac((300))((700)) = 0.43\;\left((43\% ) \right)$$

We see that with a regular lux meter-pulse meter during daylight hours we will get an underestimated pulsation coefficient (in our example we will get 20% instead of the real 43%).
In order to obtain the true value of Kp, the presence of a natural background must be taken into account in the formula for calculating the pulsation coefficient. Then the calculation of K p will look like this:

$$(K_(p.art)) = \frac((((E_(sum.\max )) - (E_(amb))) - \left(((E_(sum.\min )) - (E_ (amb))) \right)))((2\left(((E_(sum.med)) - (E_(amb))) \right))) =\\= \frac((\left(( 900 - 400) \right) - \left((600 - 400) \right)))((2\left((750 - 400) \right))) = \frac((500 - 200))((2 \times 350)) = \frac((300))((700)) = 0.43\;\left((43\% ) \right)$$

BUT! In fact, not a single luxmeter-pulsemeter can take into account the value of natural light when measuring pulsations and therefore cannot be used to measure them during daylight hours.

The professional illumination meter eLight01 is the only device that takes into account the value of the natural background illumination when calculating the pulsation coefficient. This mode is implemented in the standard delivery of the device and does not require a separate method for measuring illumination.

Method for measuring illumination and pulsations in the presence of natural light.

For the light meter-pulse meter-brightness meter eLight01, a special technique for measuring illumination and pulsation during daylight hours, which also additionally includes a method for measuring the coefficient of natural illumination (DLC) and calculating the uncertainty of illumination measurement results. This technique is included in the standard operating manual for the eLight01 device.
When performing measurements of illumination and pulsations in accordance with the operating instructions for the combined device eLight01 (according to SVMT.424179.001 RE), the following operations are performed:

1. turn on the lighting installations at least 20 minutes in advance. before starting measurements;
2. monitor the voltage in electrical network power supply for lighting installations;
3. place the eLight01 light meter sensor at the measurement point;
4. measure the level of total illumination Eo at the measurement point;
5. turn off the lighting installations and measure the level of background illumination in order to control its level and stability for 15 seconds. You should make sure that the maximum result of measuring the new illumination differs from its minimum value by no more than 10%;
6. if the level and stability of background illumination meet the requirements of the measurement methodology, then the device switches on the illumination measurement mode taking into account the natural background;
7. wait the time required for the device to measure the background illumination level until the readings appear on the device display;
8. turn on the lighting installations, read illumination measurement results and pulsation coefficient taking into account background illumination;

During measurements performed at several points, it is necessary periodically - at least every 15 minutes. control the stability of the background lighting level.

Mode for measuring illumination with the eLight01 luxmeter, taking into account natural light.

The light meter-pulse meter-brightness meter eLite01 implements unique light and pulsation measurement mode from artificial light sources during daylight hours. The measurement technique (SVMT.424179.001 MI), taking into account the natural background, is contained in Appendix D of the operating manual. Let's give short description this mode:
1) Starting the measurement of illumination and pulsations taking into account the natural background is carried out by stopping the current measurement by pressing the “SQUARE” button of the BOI-01 remote control.

2) From the measurement control menu that appears, select the “Background consideration” item and press the “Ok” button. Before starting the measurement mode taking into account the background, it is necessary to leave only the source of background illumination (that is, turn off all artificial light sources). After starting the measurement mode taking into account the background, the device at the first stage, within 10 seconds, goes into the mode of measuring and averaging the background illumination value.

After starting the measurement mode taking into account the background, a flashing “BACKGROUND” icon appears in the status bar, informing the user that this mode is enabled.
ATTENTION!!! When measuring the average background illumination value, it is strictly prohibited to perform actions that could lead to distortion of the measurement result. For example:

• change the position of the IG,
• turn on/off light sources,
• open/close window and door openings,
• movement of objects and people in the vicinity of the measurement point,
• and so on.

After completing the measurement of background illumination values, the BOI-01 remote control switches to the mode of displaying the level of general illumination minus the just measured background illumination value.
Because At this stage, the switched off light sources are not yet switched on, then the illumination readings are equal to zero (or close to it).

3) Finally, you need to turn on artificial lighting. After turning on the light sources, the first line on the BOI-01 screen will display the illumination value obtained by subtracting the background illumination level from the general illumination level. The second line represents the pulsation value of the switched on light sources, which is calculated AFTER(!) subtraction of the background values, which avoids distortion of the pulsation coefficient when using the manual background subtraction method.

4) Exit from the “Background Accounting” mode is carried out by stopping the measurement by pressing the “Square” key and selecting the “Normal Mode” menu item.

Also, exiting the “Background Accounting” mode is possible by selecting another operating mode.

ATTENTION!!! The “Background Accounting” function ensures the reliability of the measurements ONLY if the following conditions are met:

• measurements of the background and subsequent general illumination are made at one point in space;
• during measurements, movements and changes in the orientation of the IG were excluded;
• When measuring, fluctuations in background values ​​are excluded;
• background measurement and follow-up measurement of general illumination should be carried out as quickly as possible to minimize inevitable background changes over time.

Luxmeter Yu-116 is designed to measure illumination created by fluorescent lamps, incandescent lamps and natural light.

The device consists of a meter (galvanometer) and a selenium photocell with attachments. Operating principle: under the influence of light, an electric current arises in a selenium photocell, with a current strength proportional to the strength of the incident light, which is recorded by a magnetic-electric meter. The device readings are expressed in lux (lx).

The instrument panel has two scales (from 0 to 1 lux and from 0 to 30 lux) and two buttons for switching ranges with a sign for converting the illumination to the type of attachment used. On each scale, a dot indicates the starting point of measurements: 1st range from 20 lux, 2nd range from 5 lux.

On the side wall of the device there is a pole plug for connecting a photocell. The selenium photocell is housed in a plastic housing.

To reduce the cosine error, a photocell attachment is used, consisting of a hemisphere made of white light-scattering plastic and an opaque plastic ring with a complex profile.

The nozzle is designated by the letter "N" and is used only in combination with absorbing nozzles "M", "R", "G", each of these three nozzles together with the nozzle "K" forms three absorbers with an attenuation coefficient: "KM" - 10 times, "KR" - 100 times, "KG" - 1 time, which significantly expands the measurement range.

Measurement procedure:

1. Select and install absorbent nozzles (indoors they usually start with “KR” nozzles, outdoors - with “KG” nozzles).

2.Connect the photocell to the meter (observe polarity 1).

3. Place the photocell on the surface under study (plane).

4.Press the right button and take readings on a scale of 20-100

a) if the arrow is in the range from 0 to 20 lux, press the left button for indication on a scale of 5-30 lux;

b) if the arrow is in the range from 0 to 5 lux, you must switch to the “KM” attachment.

5.Reading of readings. The instrument readings are multiplied by the degree of attenuation of the nozzle and a correction factor (for incandescent lamps 1.0, for fluorescent lamps LB - 1.15, LDC-0.95, LHB-1.03).

For example: white fluorescent lamps LB, device readings 36 lux, “KR” attachment, E = 36 x 10 x 1.15 = 414 lux.

6. Turn off the device, disconnect the photocell, remove the attachments.

Determination of lighting indicators of natural and artificial lighting using a Yu-116 lux meter.

1. Determination of horizontal illumination by natural light is carried out at several points with the best and worst light conditions (near the window, in the center of the room, near the inner wall). The average illumination value is calculated.

2.Definition of KEO. The average horizontal illumination indoors and outdoor illumination are determined. KEO is calculated using the formula:

KEO = (E inside / E outside) x 100%

3. Determination of horizontal illumination at the workplace (performed in the dark). When performing a study during the day, it is necessary to determine the illumination when the lighting is on, then when it is off. The difference will be artificial lighting.

4. Determination of the unevenness coefficient. The illumination is determined at several points on the working surface at a distance of 0.5 m from each other. Illumination should differ by no more than 30% (0.3).

5. Determination of surface reflectance. The illumination of the surface (wall, ceiling, table, etc.) is determined, then the photocell is rotated 180 degrees and the reflected illumination is determined at a distance of 20-30 cm from the surface.

Calculation using the formula:

E neg.

K.neg.= x 100%

E total.

Determination of horizontal illumination of artificial light sources using the simplified “watt” method (based on specific power).

This method allows you to roughly estimate the level of artificial lighting in the room, provided that the lamps are evenly placed.

The calculation is based on the dependence of the average horizontal illumination on the total luminous flux all sources and room sizes.

1. The specific power of all sources is determined by the formula:

P = W 1 + W 2 + W N/S WHERE

P - specific power, W/m2

S - room area, m 2

W 1 ;W 2 ….. W n - power of individual light sources, watts.

2. Horizontal illumination is determined by the formula:

E = P x B, Where

E - horizontal illumination, lux

P - specific power, W/m2

B - luminous output of sources, lm/W (or illumination created by an incandescent lamp - lux, with a specific energy consumption of 1 W/m2).

Found according to table No. 4. (For fluorescent lamps B = 10 lm/W).

Table No. 4 Luminous efficiency of incandescent lamps lm/W depending on the power and type of lamp

The light meter is apparently some kind of measuring device. But not everyone will give a clear answer as to what quantity he controls. It’s good if they remember about the lighting in the room or workplace. Indeed, the device is designed to measure one of the characteristics of the lighting environment. We will try to cover this issue in detail: the purpose, principle of operation of the device and methods of its use.

A little theory

There is a lot of confusion on the Internet in scientific and technical terms related to the field of lighting technology. The same device is called differently. The device in question - a lux meter, for example, is sometimes passed off as a luminous flux meter, although this is not the case.

Luminous flux is a characteristic of a lighting element, and we can talk about this value only in relation to a specific lighting source (incandescent lamp, gas-discharge element, LED, etc.). The SI unit of this characteristic is lumen (lm). This is the luminous intensity of 1 candela (cd) per solid angle of 1 steradian (sr).

This parameter is measured using a photometric ball (spherical integrator) with a diameter of 1 or 2 meters, or with desktop integrating spheres ranging in size from 10 cm to half a meter. All these devices, naturally, are not for household use, since the price of even a small domestic device TKA-KK1 for monitoring LEDs is 35,000 rubles.

The flux of light acting per unit area is expressed by illumination. The unit of this characteristic is lux (lux) - the result of illuminating a surface of 1 m² with a flux equal to 1 lumen. The concept of “illuminance” does not refer to the light source, but to the environment.

• The luminous flux is a constant value for each source, while the illumination at each point in the room depends on several factors:
• the number of sources located near the measurement site;
• light pressure of each of them;
• distances to sources;

reflective ability of furnishings.

What is a lux meter and what is it for?

“Measure everything that can be measured, and what cannot be measured, make it measurable” - this aphorism attributed to Galileo confirms that illumination can also be measured. Since its unit is lux (in Greek - light), the device for measuring illumination is called a luxmeter (meter - I measure). It is used both indoors and outdoors. In what cases is it used? It has been established that both weak and excessively bright light has an adverse effect on processes occurring in the brain. With a lack of lighting, performance decreases, concentration decreases, and drowsiness occurs. Excessively bright light leads to stimulation of the nervous system. Both of these create the preconditions for an accident. Therefore, planned labor safety measures at workplaces include checking the lighting of workplaces. GOST R 55710-2013 sets standards for illumination (in lux) of premises for various purposes. Simplified, in the office according to sanitary standards

The process of photosynthesis in plants, which produces nutrients from carbon in the air, occurs under the influence of light. At the same time, plants react differently to temperature conditions and light levels. Almost all cultivated plants and most vegetables develop well in moderate lighting conditions. Other species require high temperatures and light. Therefore, lux meters are used to control and maintain the required illumination for various crops in greenhouses, greenhouses, and botanical gardens.

Design and principle of operation

The basis of any lux meter is a photocell - a semiconductor device in which light quanta transfer their energy to electrons, resulting in electricity. The current strength is proportional to the amount of illumination in the place where the photodetector is located.

Another element of the lux meter is an analog or digital indicator. In mechanical devices, an electric current converted by a galvanometer causes a rotational movement of the pointer needle. In digital devices, an analog signal (electric current) is converted into a digital signal using an optical-electronic converter, with the result displayed on a liquid crystal display. Structurally, both units (photodetector and converter) are made either in the form of independent elements connected to each other by wire, or in a common housing.

A monoblock is better suited for quick measurements because it weighs less and is more convenient to use. However, inconveniences arise when measuring in hard-to-reach places, with different directions and recording the readings. Therefore, when conducting workplace certification, devices with a remote photosensor are most often used. Let's look at some of the most common models.

Device for measuring illumination Yu-116

The device is still a Soviet development Yu-116 in the range from 1 to 100,000 lux. It consists of 2 parts: a selenium photocell and a pointer galvanometer, which is used to measure readings. Stored in a case unassembled, which provides reliable protection from damage. Before operation, the photodetector is connected to the converter using a plug.

The meter scale has 2 concentric arc scales. The inner one is graduated from 0 to 30 lux, the outer one - from 0 to 100. The photocell is equipped with a light-scattering attachment consisting of white translucent plastic and an opaque ring. It is designated by the letter “K”, measurements with it are made in the above ranges. There are 3 more filter attachments: M, P and T. When installed in parallel with the base attachment K, the measurement range increases respectively: 10, 100 and 1000 times.

Two buttons on the instrument panel are designed to switch from one scale to another. When enabled left button, measurements are made in the ranges: 0 – 30, 0 – 300, 0 – 3000, 0 – 30,000 (when installing the appropriate attachments). When the right one is on: 0 – 100, 0 – 1,000, 0 – 10,000, 0 – 100,000. In addition to the buttons on the case, there is a corrector for setting the dial indicator to the zero position.

Luxmeter Yu-117 differs from its predecessor only big amount buttons Instead of two scale switching keys, the device is equipped with five range switching buttons, which increases the measurement accuracy.

Buttons for turning on the device, power control and a zero control knob have also been added. Both models are powered autonomously - from a galvanic element of the Krona type with a voltage of 9 V. The price of devices from different sellers ranges from 6 to 10 thousand rubles.

How to use a lux meter?

1. You can quickly and safely find the desired measurement range for a photodetector if you act in a certain sequence:
2. Install attachments with maximum light absorption (K and T) on the photodetector, turn on the right button, which corresponds to measuring the maximum illumination - 100,000 lux. If the measuring needle does not respond, turn on the left one (up to 30,000 lux).
3. If the arrow does not move, replace the filter with a more transparent one (P) and turn it on in the same sequence: first the right button, then the left one.
4. If there is no movement, install a soft filter (M) and perform similar manipulations.

If in this case, when the left button is pressed, the result is less than 5 lux, remove the base attachment K and end the search.

Remember: excessive illumination of the selenium photosensor may affect the accuracy of the measurements, so follow the given sequence of actions.

Testo lux meters

One of the modern illumination meters, the most popular in Russia, is the digital lux meter Testo 540 (Germany). The device is made in one volume, the photocell is integrated with the body, which increases ease of use: there is no connecting wire that can get caught on something, measurements can be made with one hand.

The shape and dimensions of the device resemble cellular telephone. The same display is used to indicate the readings, and the keyboard contains only 3 buttons: power on, selection of the measurement system (SI or American - foot-candle) and saving the results. Measuring range: 0 – 100,000 lux or 0 – 93,000 fc.

The device is ideally suited for use in everyday life. With its help, you can measure the lighting level in living rooms, schools, kindergartens, greenhouses, potato storage rooms, and so on. Operating the device is extremely simple: press the power button, select the system (triangle) and that’s it. The result will appear almost instantly. To save the measurement result, press the “mode” button.

The Testo 545 digital device belongs to the class of professional devices for measuring environmental illumination. The light receiver is made separately from the electronic unit and is connected to it by a conductor. Different from younger brother b O greater functionality:

• memory for storing up to 3000 measurement results;
• storing 99 measurement locations in memory;
• connection to personal computer;
• constructing a three-dimensional graph of the amount of illumination within the room;
• printing data on a printer.

This device is used in the process of measuring the illumination of buildings, structures, as well as streets, roads and other public places. The price of the Testo 540 lux meter is comparable to the price of the Yu-116 device (about 10 thousand), and Testo 545 is sold for 35 thousand rubles.

A lux meter is one of the most accessible and at the same time effective instruments for measuring the illumination parameters of an object. Its use provides comfortable conditions for a person, both in a work environment and in everyday life. We hope that this article will help you navigate when choosing a device with the necessary capabilities for a reasonable price.

Measurement of artificial illumination and ripple factor in the presence of natural light

Measurement of artificial illumination and ripple factor in the presence of natural light.

Measurement of artificial illumination during the daytime.

MUK 4.3.2812-10 establishes the requirements that it is allowed to measure artificial illumination and pulsation coefficient only if the natural background illumination at the surveyed point does not exceed 10% of the measured artificial illumination. That is, this means that for most rooms with external windows such measurements should be carried out in the dark. Such requirements are introduced in order to eliminate the influence of natural daylight on the measurement results.

The presence of even relatively small windows in the examined premises leads to a significant distortion of the results of measurements of artificial illumination and pulsation coefficient, especially on sunny days.

The ability to measure artificial illumination and pulsations in the dark is often complicated by the fact that access to many objects is closed after hours or at night. At the same time, it is not possible to organize the staff of these facilities to provide access to them at night.

Another obstacle to measuring artificial illumination and its pulsation coefficient in the dark is the polar day, which occurs in summer in many northern regions of Russia. The 24-hour presence of sunlight makes it impossible to carry out such measurements for several months.

Illumination measurements with natural background subtraction.

A solution to the problem of the presence of a natural background when measuring artificial illumination could be measurements with windows covered with light-proof materials (curtains, blinds, shutters, etc.). However, it is not always possible to close window openings, especially in industrial, public and office buildings with a large glass area.

In such cases, the only way to measure artificial illumination is the method of subtracting the natural background from the value of the total (total) illumination. This method is based on the fact that at each point in space the resulting illuminance is the sum of all illuminances created at a given point by each individual light source:

where E1, E2, E3,.....,EN is the illumination created at a given point by light sources number 1, 2, 3, ...., N.

That is, in the presence of natural and artificial lighting, the total illumination will be their sum:

where Eest is the background of natural illumination, Eisk is the value of artificial illumination.

In the example shown in Fig. 1, we see

that the background natural illumination of 100 lux (Eest, yellow line) was added to the artificial illumination level of 200 lux (Eisk, blue line) and the total illumination level was 300 lux (E, green line).

Thus, if, with artificial lighting turned off, at the examined point we measure the illumination due to the presence of natural light and subtract it from the value of the total illumination at the same point, then we will obtain the value of artificial illumination:

The limits of the main relative error of the measurement result performed in this way, provided that the contribution of the random component is insignificant, can be estimated as θ = 1.1√2 θpr, where θpr is the relative error of the measuring instrument, (θ = 12.5%, with θpr = 8 %), with a confidence level of P = 0.95.

Measurements of artificial illumination with subtraction of the natural background can be performed, for example, with a conventional luxmeter-pulsemeter-brightness meter "Ecolight-02". However, it must be taken into account that carrying out such two-stage measurements is only possible on the condition that, during the time that both stages of measurement are carried out, the level of natural light remains constant. Those. Such measurements should be carried out under the most stable light conditions, namely:

• dense clouds;
• lack of movement of people and objects in the area of ​​the measurement point;
• minimum time between measurement steps
• and so on.

Measurement of the pulsation coefficient of artificial lighting in the presence of a background of natural light.

We have described a method for measuring artificial illumination in the presence of a natural background. They even showed how this can be done using a regular lux meter and manual recalculation of the measurement results. However, this method cannot be directly applied to the measurement of the ripple factor of artificial lighting. Let's illustrate this with an example.

If you look at Fig. 2, you can see that in our example maximum value pulsations of artificial lighting (blue curve) Emax = 200 lux, with the minimum value Emin = 100 lux. Then, using the formula for calculating the pulsation coefficient from the article “Pulsations of illumination and brightness,” we obtain that:

those. Kp = (200-100) / (200+100) = 100/300 = 33.3%.

However, if we measure the pulsation coefficient of the total (artificial and natural) illumination with a conventional lux meter-pulse meter (for example, the same “Ecolight-02”, which helped us a lot in the previous example with subtracting the background), then, in the presence of a background of natural illumination, Eest = 100 lux (yellow straight line), we get the values ​​for the total illumination (Fig. 2, green curve) Emax = 300 lux, Emin = 200 lux. Substituting these values ​​into formula (4), we get:

Kp = (300-200) / (300+200) = 100/500 = 20% (!).

The underestimation of the illumination pulsation coefficient occurs due to the addition of a constant level from natural lighting. Since a conventional lux meter cannot take into account the presence of a natural background when calculating the pulsation coefficient, it is IMPOSSIBLE to measure the pulsations of artificial lighting with such a device in the presence of a natural background!!!

However, there is a way to get the correct ripple factor of artificial lighting when there is a natural background. To do this, before calculating Kp, it is necessary to subtract the background value at a given point from the maximum (Emax) and minimum (Emin) values ​​of total illumination. Having carried out the specified background subtraction, we obtain the following expression for the ripple coefficient:

We simplify and get the following formula:

Using this algorithm, we will obtain the true value of the pulsation coefficient of artificial lighting. Let's try to calculate Kp from our example in Fig. 2., where we have the level of natural illumination Eest = 100 lx (yellow straight line), the maximum illumination value Emax = 300 lx and the minimum illumination value Emin = 200 lx. Using formula (5), we calculate the pulsation coefficient of artificial lighting taking into account the natural background:

Kp = (300-200) / (300+200-2×100) = 100 / (500-200) = 100/300 = 33.3%

We see that, having carried out calculations using the proposed algorithm, we obtained the same value of the artificial lighting pulsation coefficient as when calculating it in the absence of a natural background. That is, if such an algorithm for calculating the pulsation coefficient is implemented in a lux meter-pulse meter, taking into account the presence of a natural background, then, as a result, we will receive the correct value. Of course, subject to the same requirements for the conditions for carrying out such measurements that were formulated above for carrying out measurements of artificial illumination, taking into account the presence of a natural background.

The measurement error of the pulsation coefficient of artificial illumination in the presence of a natural background can be estimated by the value of the main relative error of the measuring instrument, which for this parameter is 10%.

How to measure the pulsation coefficient of artificial lighting in the presence of a natural background using the Ecolight-01 luxmeter-pulsemeter.

The proposed algorithm for measuring pulsations of artificial lighting in the presence of a natural background is implemented in the luxmeter-pulsemeter-brightness meter "Ecolight-01". This device has a special measurement mode taking into account the presence of natural light. Let's give a fragment with a description of this mode from the Operation Manual for "Ecolight-01".

2.3.4.5. Measurement of illumination and pulsations taking into account the level of background illumination is carried out in the mode of stopping the current measurement by selecting the menu item "Background accounting".

Before starting the measurement mode taking into account the background, it is necessary to leave only the source of background illumination (for example, extinguish all artificial light sources). After starting the measurement mode taking into account the background, the device at the first stage, within 10 seconds, goes into the mode of measuring and averaging the background illumination value (Fig. 10).

After starting the measurement mode taking into account the background, a flashing icon appears in the top information line informing the user that this mode has been enabled.

ATTENTION!!! When measuring the average background illumination value, it is strictly prohibited to perform actions that could lead to distortion of the measurement result. For example, change the position of the photo head, change the light situation at the measurement point (turning on/off light sources, opening/closing window and door openings, moving objects and persons in the vicinity of the photo head, etc.).

After completing the measurement of background illumination values, the device switches to the mode of displaying the level of general illumination minus the just obtained background illumination value. Because At this stage, the switched off light sources are not yet switched on, then the illumination readings are equal to zero (or close to it). (Fig.11)

After turning on the light sources, the BOI-01 screen will display the illumination value obtained by subtracting the background illumination level from the general illumination level. The second line represents the pulsation value of the switched on light sources, which is calculated AFTER(!) subtraction of the background values, which allows you to avoid distortion of the pulsation coefficient when using the manual background subtraction method. (Fig. 12).

ATTENTION!!! The “Background Accounting” function ensures the reliability of the measurements ONLY if the following conditions are met:

• measurements of the background and subsequent general illumination are made at one point in space;
• during measurements, movements and changes in orientation of the photo head are excluded;
• When measuring, fluctuations in background values ​​are excluded;
• The background measurement and the subsequent total illuminance measurement should be carried out as quickly as possible to minimize inevitable background changes over time.