Illumination should be measured at least once a month, and in combined lighting systems, illumination should be measured separately: from the entire system as a whole and from lamps of one general and local lighting.
To check the level of actual illumination, the person responsible for operating the lighting installation must have a Yu-16 lux meter (Fig. 24) with a selenium photocell. The components of the lux meter are a dial meter 1 (a conventional galvanometer with a switch for measurement limits), an external light receiver - a selenium photocell 2, connected to the meter with a flexible wire 3, and an absorber-plate made of milky-neutral organic glass, which covers the light receiver at high illuminances (over 500 OK).
The luminous flux incident on the plane of the photocell causes a photocurrent proportional to the magnitude of the luminous flux. By the deflection of the galvanometer needle, calibrated in lux, one can judge the amount of illumination. The lux meter should be stored in a dry place; when not working, the photocell should be covered with a light-proof case. The lux meter calibration should be checked twice a year.
Rice. 24. Lux meter:
1 - dial meter (conventional galvanometer with a switch for measurement limits); 2 - external light receiver - selenium photocell; 3 - flexible wire
When using the Yu-16 lux meter, you should be aware that the selenium element is not equipped with a correction filter, therefore, according to the manufacturer’s recommendation, when measuring illumination from LD fluorescent lamps, it is necessary to enter a correction factor of 0.9, and when measuring illumination from LB lamps, a correction factor coefficient 1.1. In addition, when using a lux meter, the readings should be taken only after the galvanometer needle is stationary. This is explained by the fact that the selenium photocell has inertia and when the illumination changes, the current in its circuit is not established immediately; In order not to damage the galvanometer, when using a luxmeter, you must first set its switch to the position for measuring the maximum luminous flux (500 lux), and then move lower (100 and 25 lux). The illumination is measured selectively at workplaces located in various areas of the workshop, both under the lamps and in the intervals between them. When choosing locations for measuring illumination, it is necessary to take into account the location of general lighting fixtures. The photocell of the luxmeter should be located directly at the location of the working surface of the workpiece, the surface of the device, scales or the surface of the table on which this or that production operation is performed. It is recommended to select places for measuring illumination in accordance with the nomenclature of workplaces (nature of work) listed in industry illumination standards and sanitary standards, which will ensure easy comparison of the actual measured illumination with the standardized one.
The results of illumination measurements are recorded in a special log of the operation of the lighting installation.
SELF-TEST QUESTIONS
1. What lighting systems exist? Please rate them.
2. Describe the natural lighting arrangement.
3. Describe the artificial lighting device.
4. What determines the glazing area of windows and skylights and the minimum artificial illumination?
5. How to properly operate lighting installations and what instruments are used to measure illumination?
Illumination is controlled using special devices - luxmeters. Lux meters are used for illumination measurements, created by both artificial and natural light sources. Unit illumination measurements- lux (lx), reflects the amount of luminous flux incident on a unit surface. In England and the USA, illumination is measured in foot-candles (fc) - one lumen per square foot (1 fc = 10.76 lux); in some countries in "phot" (phot) - one lumen per square centimeter (1 phot = 10,000 lux).
Insufficient light leads to increased fatigue, decreased performance and negatively affects the quality of vision. Although several parameters are taken into account when assessing light, including luminous intensity and brightness, it is illuminance that is the key parameter.
The operating principle of lux meters is extremely simple: it is based on the operation of a photocell that converts light energy into electric current. All lux meters used for illumination measurements, are small in size and weight.
With the help of which it is carried out illumination measurement, primarily used by occupational safety specialists. Mandatory control of the illumination of the workplace, according to current sanitary rules, must be carried out at least once a year. Current purchase light measuring device and for home use.
The choice of a lux meter largely depends on the tasks assigned to the device. The most reliable and convenient light meter— . It is capable of measuring light levels ranging from 1 to 200,000 lux (PG 3.0%). The continuous operation time of this device is at least 8 hours. Suitable for use in museums, libraries and research centers is an instrument complex created specifically for cultural and art institutions. In addition to the functions of a lux meter, this device combines the functions of a UV radiometer, a humidity and air temperature meter. Moreover, its weight is only 430 grams.
Today buy devices for measuring illumination You can directly contact the manufacturer - NTP TKA LLC. This scientific and technical enterprise has been developing and producing control and measuring instruments since 1999. Every light meter, released by NTP "TKA", meets state standards, has certificates and is easy to use.
Brightness measurement
One of the most important characteristics affecting human performance is the brightness of light. This characteristic is equal to the ratio of the intensity of light in a particular direction to the area of projection of the luminous surface onto a plane perpendicular to the observation axis. Unit brightness measurements- candelas per square meter (cd/m2). Brightness characterizes the spatial and surface distribution of luminous flux. For brightness measurements special devices are used - .
Brightness meter converts the luminous flux created by a natural or artificial light source into a continuous electrical signal proportional to the illumination level. This information is displayed on the display brightness measuring device as a digital value.
First of all, brightness measurement necessary to control the level of light sensation in the human eye. Insufficient or excessive brightness can cause rapid fatigue, blurred vision and, as a result, complete or partial loss of performance. Modern brightness measuring device necessary in order to monitor and promptly respond to changes in this parameter. It must be remembered that the light generated by the source must have such a spectral distribution of energy brightness density that would ensure an unambiguous assignment of one color or another to it. The need for constant monitoring is due to the use of modern technology - LCD monitors, televisions, fluorescent lamps, and the introduction of LED lamps. To eliminate interfering mirror reflections in displays, the brightness of ceiling or recessed luminaires at least in: two main planes should not exceed 200 cd/m2.
Limiting the brightness of visible surfaces of lamps is an important indicator of lighting quality, since brightness is the light value to which the human eye directly reacts. Exceeding the brightness values prescribed by norms and standards is unacceptable due to the likelihood of glare.
Brightness meter- an essential device for occupational health and safety services. Brightness meters are widely used in cinemas, science centers, educational and medical institutions, museums and libraries. Without exception, they are compact in size and light in weight.
Brightness meters There are overhead and projection types. Surface-mounted devices are used to measure flat extended self-luminous objects. For example, to measure the brightness of flat lamps or monitors. The design of the surface-mounted brightness meter is simple. A projection-type brightness meter has an optical design that allows you to cut out a solid corner of the object being examined and project this fragment of the object into a photosensor. Devices of this type make it possible to measure the brightness of distant objects (lanterns, ceiling lamps, signal indicators) of complex shape, as well as the reflected brightness of non-self-luminous objects - walls, cinema screens, road signs and other similar objects. Obviously, the scope of application of a projection brightness meter is much wider than that of an overhead brightness meter. But it has a much more complex design and a much higher price. When searching for the required model be sure to pay attention to the lower sensitivity limit of the measuring instrument. WITHthe spectral sensitivity of the brightness meters in our case is normalized by the functions of the relative spectral luminous efficiency of monochromatic radiation for daytime vision (L>10 cd/m 2 ).
Selecting a device that performsbrightness measurement, depends on the tasks assigned to him. For example, a device combines the functions of a brightness meter (overhead method), luxmeter and pulse meter, and allows for comprehensive control over all lighting parameters in the workplace. I rkomer indispensable when installing film projectors and equipment in cinema halls, and - will not only allow you to control the brightness of movie screens, but also measure the color characteristics of the image created by digital movie projectors (chromaticity coordinates and correlated color temperature).
Measurement of optical parameters of LEDs
LED technologies used today are increasingly replacing traditional types of lighting. This is due to their characteristics: high vibration resistance, ease of maintenance and long service life. Thanks to sufficient contrast of the emitted lighting and optimal color temperature, LEDs are increasingly used for general lighting of residential buildings and office premises.
However, the introduction of advanced lighting technologies into everyday life requires careful monitoring optical parameters of LEDs. Parameter measurement LEDs includes luminous flux measurement, spectral analysis of lighting and its color characteristics. AND measurements are taken using the device.
An indisputable assistant in calculating the energy efficiency of lighting devices can be, which allows you to make measurementsphotosynthetic photon flux density PPFD[
µmol/s/m²].
For LED luminous flux measurements The goniometric method or the integrating sphere method can be used. LED measurement The goniometric method is based on step-by-step fixation of the values of the intensity of the luminous flux emitted by the source when it is rotated through a known angle. The integrating sphere method, in turn, allows you to obtain the same data much faster by performing simple technical operations. In it, the luminous flux of the LED is compared with the pre-calculated flux of the reference light source (relative photometry).
LED measurement The integrating sphere method is carried out using a photometric ball, which allows one to obtain the most accurate data. In accordance with Lambert's law, the ball scatters the light flux evenly, which allows you to produce as quickly as possible measurement of optical parameters of LEDs.
It is on the basis of the integrating sphere method that specialists from the scientific and technical enterprise “TKA” created. Using this device you can carry out as accurately as possible LED measurement in real time. In it, the luminous flux of the LED is compared with the pre-measured flux of the reference light source. The light receiver is a photodiode installed in the lower hemisphere. Because of this, it is possible to move from relative measurements to direct measurements of luminous flux in lumens (absolute photometry). The small size of the device greatly facilitates the process measuring the luminous flux of single LEDs. At the beginning of 2014, the device has no direct domestic analogues, and its affordable price makes the device number one for LED measurements.
Measuring indoor temperature and humidity
Modern humidity measuring device, this is a device that performs accurate measurements of humidity levels necessary to ensure working conditions in the construction, food, oil and gas and other industries. Depending on the area of application of the device, there are structural differences.
The familiar to many people are gradually becoming a thing of the past. temperature meters based on mercury thermometers. Modern thermometer is a digital device that has a number of advantages over its mercury predecessor. Firstly, it does not contain mercury, and therefore is not subject to various prohibitions on use (recently, various government agencies have issued decrees banning the use and transportation of mercury temperature meters). And this trend is observed in most world countries.
Secondly, its body is made of stainless steel, which guarantees the strength of its body much higher than mercury glass. Thirdly, digital thermometers do not require preliminary calibration; temperature corresponds to the actual one. Fourth, the cost of digital ownership temperature meter significantly lower than the cost of a mercury analogue, because when using mercury thermometers, significant funds will be needed to clean up the area after an accidental spill of this dangerous metal.
The issued scientific and technical progress "TKA" additionally display parameters calculated in real time: wet bulb temperature(tvl, °C) and dew point temperature(t tr, °C).
Relative humidity is a defining characteristic in the wood, printing and agricultural industries. When working with wood and paper in production facilities, as well as for preserving agricultural products in warehouses, it is a reliable assistant. thermohygrometer. It will protect wood products in very dry air or during varnishing processes. Will adjust the necessary air temperature and humidity indicator for storing paper sheets. It will help keep the harvest safe and sound.
Control over humidity air will help increase livestock productivity and reduce the cost of feed and energy resources, and will also provide favorable sanitary and hygienic conditions on farms.
The current generation of the NTP "TKA" company are mobile and compact devices that can simultaneously serve several buildings. In addition to the industries mentioned above, thermohygrometers They are also used in the textile (in the production of yarn and fibers) industry, as well as in the production of tobacco products.
The devices produced by NTP "TKA" implement a unique ability to determine values of THC and WBGT indices in real time thanks to the simultaneous measurement of air temperatures and inside a black ball, air humidity and calculation of exact values temperature wet thermometer and according to a special program protected by a Certificate of Official Registration of a Computer Program. Additional simultaneous determination of average radiation temperature and thermal radiation flux density provides an effective and reliable assessment of possible thermal overheating when examining a hot environment.
A new line is being developedautonomous recorders, whichdesigned to measure relative humidity, temperature and atmospheric pressure and recording them in the internal memory and can additionally be equipped with a data transfer function both via USB, and by WiFi, with the possibility of combining several such devices into a measuring and information network.
Illumination- a physical quantity characterizing the illumination of a surface created by a luminous flux incident on the surface. The SI unit of illumination is the lux (1 lux = 1 lumen per square meter), and the GHS unit is the phot (one phot is equal to 10,000 lux). Unlike illuminance, the expression of the amount of light reflected by a surface is called brightness.
Illumination is directly proportional to the luminous intensity of the light source. As it moves away from the illuminated surface, its illumination decreases in inverse proportion to the square of the distance.
When light rays fall obliquely towards the illuminated surface, illumination decreases in proportion to the cosine of the angle of incidence of the rays.
Luxmeter(from Latin lux- light and... meter), a portable device for measuring illumination, one of the types of photometers. The simplest lux meter consists of a selenium photocell that converts light energy into electric current energy, and a dial microammeter with scales graduated in lux that measures this photocell. Different scales correspond to different ranges of measured illumination; The transition from one range to another is carried out using a switch that changes the resistance of the electrical circuit. Even higher illuminances can be measured using a light-scattering attachment placed on the photocell, which attenuates the radiation incident on the element by a certain number of times (constant over a wide range of radiation wavelengths).
The relative spectral sensitivity curves of a selenium photocell and the average human eye are not the same; Therefore, the Luxmeter readings depend on the spectral composition of the radiation. Typically, devices are calibrated with an incandescent lamp, and when measuring illumination created by radiation of a different spectral composition (daylight, fluorescent lighting) with a simple lux meter, correction factors obtained by calculation are used. The measurement error of such a lux meter is at least 10% of the measured value.
Luxmeters of a higher class are equipped with corrective filters, in combination with which the spectral sensitivity of the photocell approaches the sensitivity of the eye; a nozzle to reduce errors when measuring illumination created by obliquely incident light; control attachment for checking the sensitivity of the device. The spatial characteristics of lighting are measured by a Luxmeter with spherical and cylindrical attachments. Luxmeter models are available with devices for measuring brightness. The measurement accuracy of the best Luxmeter is about 1%.
Digital light meter MS6610
There is a data hold mode on the display (Data Hold).
Characteristics:
- Display: 3 1/2 - digit, max. value - 1999
- Light intensity measurement range: 0~2000lux, 2000~19990lux, 20000~50000lux
- 3 ranges: x1, x10, x100
- Accuracy: ±5%
- Photodetector: one silicon photodiode with filter
- Photodetector dimensions: 83x52x20.5
- Dimensions/Weight: 125.5x72x27mm/180g
Poor lighting in premises, a workplace or a room in an apartment negatively affects human health, reduces concentration, performance, irritability and mental disturbances. Very bright light is also an irritant and does not provide anything positive for a person.
Therefore, it is necessary to ensure normal illumination of the premises, which is regulated by a certain SNiP standard. This requires a simple installation of appropriate lighting lamps for each room.
Illumination of premises in nominal terms is the flux of light that is emitted onto the surface at right angles per unit area. When light falls at an acute angle, the illumination decreases depending on the angle of inclination.
Illumination is measured in lux, which is equal to 1 lumen (unit of luminous flux) per m2.
The illumination of the premises directly depends on the strength of the light that comes from the source. The greater the distance from the light source to the surface, the lower the illumination parameter.
Norms
Each type of room has its own lighting standards. For example, for a grocery store, the highest pulsation value is set at 15%, illumination at 300 lux, but for a sporting goods or building materials department, the standards are completely different. The rules also establish certain permissible illumination for clinics, kindergartens, car services and other facilities.
Example of illumination calculation
Let's determine the required lighting for the bedroom. The bedroom area is 25 m2. The value of the norm according to the rules for rooms of this type is multiplied by the area: 150 x 22 = 3300 lux. The total luminous flux of lighting devices at this level of illumination must be at least 3300 lumens.
Now all that remains is to choose the right lighting lamps for the bedroom. When choosing, you can, for example, purchase three such 12-watt lamps. This will ensure the creation of a luminous flux of 3600 lumens, as can be seen from the table values.
This calculation is approximate, since LED lamps have different light parameters depending on the manufacturer. Thus, you can easily independently calculate the required power and type of lamps to create standardized illumination of any room in accordance with the rules of SNiP.
Instruments for measuring illumination
To measure room illumination, various devices are used, which have their own design features and measurement methods. Let's look at the main devices in more detail.
Lux meters are divided into electronic and analog, which are no longer produced, and only old samples of such models remain.
This lux meter is used:
- Checking compliance of room illumination with regulatory data.
- Measuring lighting parameters when carrying out work to assess working conditions.
- During electrical installation work to compare illumination indicators with calculations for lighting devices.
The principle of operation of the lux meter is based on the operation of the built-in one, to which the flow of light is directed. In this case, a significant flow of charged particles appears in the photocell. As a result, a flow of electric current appears, the strength of which depends on the strength of the light flux directed at the photocell. Usually this parameter is displayed on the instrument scale.
Types of lux meters
Depending on the location of the sensor that measures room illumination, lux meters are divided into types:
- Monoblock (one-piece device) . The sensor is fixed in the device body itself.
- Device with remote sensor , connected by a flexible wire.
To make simple measurements, a regular monoblock lux meter is suitable, without various auxiliary functions. To determine several illumination parameters when performing professional calculations, it is necessary to use devices that have an additional set of functions. Such devices have built-in memory and can determine average parameter values.
A significant advantage for a lux meter is the presence of special filters that help more accurately determine the value of light intensity that comes from lighting devices with different shades of colors.
The presence of a remote sensor in the lux meter makes it possible to determine the illumination with greater accuracy, since the influence of external factors is reduced. Modern models have a liquid crystal display. It makes it much easier to take readings from the device.
Devices for photographic equipment
Photographic equipment uses devices such as exposure meters and exposure meters . They are designed to determine the parameters of brightness and exposure illumination. By determining the values of these indicators, a professional photographer can obtain high-quality photographs.
Exposure meters are divided into types:
- Internal.
- External.
Flash meters
Such devices are designed to measure illumination when photographing. In this case, pulse-type lighting devices (photo flashes) are used as an additional element. In modern camera models, the flash meter is located in the body. It changes the flash output at different light levels.
Professionals use flash meters with a remote sensor; they more accurately determine the illumination.
Photometer
Such a device is called a multimeter. It is a more modern flash meter model. Its advantage is the combination of exposure meter and flash meter options.
Light pulsation
The uniformity of the luminous flux of lighting devices leaves much to be desired. The effect, expressed in the presence of fluctuations in the light flux, is not visible to the eye, but its impact on human health is of great importance.
The danger of such light is that it is visually impossible to determine the presence of light pulses. And as a result of their action, sleep may be disrupted, discomfort, depression, weakness, heart failure and other symptoms may occur.
The pulsation parameter is its coefficient, which expresses the force of change in the flux of light directed per unit surface area over a period of time. The formula for calculating this coefficient is quite simple. The irradiance ripple factor is determined by the difference between the highest and lowest illuminance for a certain time, divided by twice the average illuminance, and the result is multiplied by 100%.
Sanitary regulations determine the upper limit of the pulsation coefficient. In the workplace it should be no more than 20%, and depends on the degree of responsibility of the employee’s work. The more responsible the work, the lower the lighting pulsation coefficient should be.
For administration premises and offices with intense visual work, this coefficient should not rise above the 5% mark. In this case, the flow of light with a pulsation frequency of up to 300 hertz is taken into account, since there is no point in taking a higher frequency into account, due to the fact that it is not perceived by the human eye and does not have a negative effect.
Determination of lighting pulsation
To determine the pulsation of light, an effective simple device is used that measures the brightness, pulsation and illumination of rooms, and is called a luxmeter-pulsometer-brightness meter.
Device functions
- Measuring the pulsation of light waves that occur when various lighting devices flicker.
- Measuring the lighting pulsation of computer monitors and other screens.
- Determination of room illumination.
- Determining the brightness of lighting devices and monitors.
The principle of operation of the device is to check the lighting level using a photosensor with further signal conversion and displaying the result on a liquid crystal display.
The light pulsation coefficient can be determined using a program on a computer, or you can analyze the measurements yourself. To analyze measurements on a computer, a special program “Ecolight-AP” is used, which works with the device “Ecolight-02”.
Distinctive features of measuring instruments that detect pulsations are sensitivity levels, type of power supply and quality of photosensors.
The highest pulsation coefficient is produced by LED lamps, when using which this parameter sometimes reaches 100%. and have a low pulsation coefficient. Incandescent lamps have a pulsation coefficient of no higher than 25%. In this case, the cost and quality of the lamps do not play a role. Even expensive lamps can produce significant levels of light pulsation.
Methods for reducing lighting pulsation
- The use of lighting devices operating on alternating current with a frequency of more than 400 hertz.
- Installation of lighting fixtures for different phases with a three-phase network.
- Installation of a ballast compensation device () into the lighting device and special connection of offset lamps. The first lamp operates on a lagging current, and the 2nd on a leading current.
- Installation of lamps with electronic ballasts. They are equipped with an electronic ballast that smoothes out ripples and stabilizes the voltage.
If lighting devices in a room are connected to one phase, then connecting them to different phases will be problematic. Therefore, it will be more convenient to purchase lamps with electronic ballasts. Their advantage is that they comply with all regulations.
Controlling the level of lighting pulsation is necessary for human health, since deviations from the norms lead to disruption of the performance and well-being of employees.
For residential buildings, indoor lighting is also important. The pulsation of light is not visible, but over time its negative impact becomes apparent.
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