Artificial lighting is provided in rooms where there is not enough natural light or to illuminate the room during those hours of the day when there is no natural light.
By design, artificial lighting can be of two types: general and combined, when local lighting is added to the general lighting, concentrating the light flux directly at the workplace. General lighting is divided into general uniform lighting (with uniform distribution of luminous flux without taking into account the location of equipment) and general localized lighting (with distribution of luminous flux taking into account the location of workplaces).
Combined lighting has a number of advantages over general lighting:
The total consumption of electrical energy is reduced by reducing the installed power of light sources due to the close location of local lamps to the working surface;
Electrical energy is saved by turning off local lighting fixtures in vacant workplaces;
The visibility of relief details is increased due to the individual selection of local lamps;
Shadows and glare in workplaces are limited;
It is possible to create high levels of illumination on inclined surfaces.
The use of local lighting alone inside buildings is not allowed. In industrial enterprises, it is recommended to use a combined lighting system where precise visual work is performed, where equipment creates deep, sharp shadows, or work surfaces are located vertically. A general lighting system can be recommended in rooms where the same type of work is carried out throughout the entire area, as well as in administrative offices, warehouses and passageways. If workplaces are concentrated in separate areas, for example, at marking plates, quality control tables, it is advisable to resort to localized placement of general lighting fixtures.
Artificial lighting eliminates the above-mentioned disadvantages of natural lighting and provides optimal light conditions.
Artificial lighting is divided into working, emergency, security and duty.
Work lighting is mandatory for all premises, buildings, as well as areas of open spaces. It serves to ensure normal working conditions, the passage of people, and the passage of vehicles.
Emergency lighting is divided, in turn, into safety and evacuation lighting.
Security Lighting are provided in cases where the shutdown of working lighting and the associated disruption of maintenance of equipment and mechanisms may cause:
Explosion, fire, poisoning of people;
Long-term disruption of the technological process;
Disruption of the operation of such facilities as power plants, radio and television transmission and communication centers, control centers, pumping installations for water supply, sewerage and heating, ventilation and air conditioning installations for industrial premises in which the cessation of work is unacceptable, etc.;
Violation of the regime of children's institutions, regardless of the number of children in them.
Evacuation lighting In premises or places where work is carried out outside buildings, the following should be provided:
In places dangerous for the passage of people;
In passages and stairs used for evacuating people (if the number of evacuees is more than 50 people);
Along the main passages of industrial premises where more than 50 people work;
On stairwells of residential buildings six floors or more high;
In industrial premises without natural light, etc.
Emergency lighting light sources can be turned on simultaneously with the main lighting luminaires and remain constantly lit or turn on automatically only when the power supply to normal lighting is interrupted.
Security lighting(in the absence of special technical security means) is provided along the borders of territories protected at night.
Emergency lighting- lighting of premises during non-working hours. If necessary, part of the working or emergency lighting fixtures can be used for emergency lighting
To artificially illuminate work areas with electric light, direct, reflected and diffuse light is used (Fig. 4.4).
Rice. 4.4. Types of lamps depending on the share of luminous flux falling on the lower hemisphere:
P - direct light; R - diffused light; ABOUT - reflected light
The choice of certain luminaires for light distribution depends on the nature of the work performed in the room, the possibility of dust, air pollution, and the reflectivity of surfaces in the room. For example, diffused and reflected light luminaires are used in rooms where greater uniformity of lighting is required, when it is necessary to soften the sharpness of shadows or highlights on highly reflective surfaces, etc.
Standardization of artificial lighting parameters.
According to SNiP 23-09-95, the standardized parameters of artificial lighting are:
Illumination of the working surface E, OK;
Blindness rate R,%;
Illumination pulsation coefficient K p,%.
Illumination of the working surface - luminous flux density on the surface illuminated by it:
, (4.4)
where Ф - luminous flux density, lm; S- surface area illuminated by luminous flux, m2.
The standard value of illumination is set to its minimum value at which performing a certain job does not harm the worker’s vision. E min is set for the darkest area of the working surface. It is established according to the characteristics of visual work, which is determined by visual tension when performing this work.
There are eight categories of visual work in total. The first six categories (from work of very high precision to rough visual work) are classified depending on the smallest size of the object of discrimination (the thickness of the mark on the scale of the device, the thinnest line of the drawing, a crack in the product, etc.), the contrast of the object of discrimination with the background ( small, medium, large) and background characteristics (light, medium and dark). VII category sets the requirements for working with luminous materials and products in hot shops, VIII - for general monitoring of the progress of work.
Blindness rate- criterion for assessing the glare of a lighting installation, determined by the expression
P = (S- 1) × 100%, (4.5)
Where S- glare coefficient equal to the ratio of threshold brightness differences in the presence and absence of blinding sources in the field of view. In industrial premises, the glare rate should not exceed 20-40%, depending on the level of visual work.
When lighting industrial premises with gas-discharge lamps powered by alternating current of industrial frequency (50 Hz), the depth of illumination pulsation is limited.
Illumination pulsation coefficient- a criterion for assessing the relative depth of fluctuations in illumination as a result of changes in time of the luminous flux of gas-discharge lamps when powered by alternating current, expressed by the formula
Where E max, E min- respectively, the maximum and minimum values of illumination during the period of its fluctuation, lux; E c r- average illumination value for the same period, lux.
The value of the pulsation coefficient, depending on the lighting system and the nature of the work performed, should not exceed 10-20% (for work related to monitoring computer video terminals, K p- no more than 5%).
Currently, the following light sources are used for artificial lighting:
Incandescent lamps, including halogen;
Arc sodium gas discharge lamps;
Arc mercury halogen lamps.
If necessary, distinguish colors;
For work involving prolonged eye strain;
In production facilities with a continuous production cycle or work in three shifts;
In children's and school institutions;
In rooms where lighting is used as an architectural decoration of interiors.
The disadvantage of the most common fluorescent lamps is the pulsation of their light flux, the depth of fluctuation of which can reach 55%. Pulsation of the light flux, a multiple of the frequency of alternating current, can in certain cases cause a “stroboscopic effect”, which disrupts the correct visual perception of moving objects, when a rotating object may appear motionless. Pulsation of the light flux leads to rapid visual fatigue. In modern multi-lamp lamps, with the help of special electrical circuits for connecting lamps, this drawback can be eliminated.
To calculate a lighting installation with uniform placement of general lighting fixtures and a horizontal working surface, the main method is the so-called luminous flux utilization coefficient method or the lighting installation utilization coefficient method. This method takes into account both the luminous flux of light sources and the luminous flux reflected from the walls, ceiling and other surfaces of the room.
The calculation is carried out according to the formula:
Where F l- luminous flux of one lamp, lm; E n- normalized illumination, lux; S-room area, m2; Z= 1.15 - coefficient taking into account the ratio of average illumination to minimum, when illuminated by lines of fluorescent lamps Z= 1,1; K 3- safety factor taken depending on air pollution in the room; N- number of lamps; h- luminous flux utilization factor.
The luminous flux utilization coefficient is determined using lighting tables. It depends on the efficiency and luminous intensity distribution curve of the lamp, the reflection coefficients of the ceiling, floor and walls, the height of the lamp suspension above the design surface and the configuration of the room, which is determined by the index (indicator) of the room:
Where A, b- width and length of the room, m; h p- height of the lamp suspension above the design surface, m.
The minimum required illumination is established according to SNiP 23-05-95 or industry standards. The number of lamps is selected taking into account their optimal location. Based on the required luminous flux, the nearest standard lamp is selected, its power is determined, and then the power of the entire lighting installation is determined.
To calculate localized and local illumination of horizontal and inclined surfaces and illumination in cases where reflected light can be neglected, the point method is used, where the formula is used
Where E- illumination, lux; I- luminous intensity in the direction from the source to a given point on the working surface, cd; a- the angle between the normal to the working surface and the direction of the light flux to the source; K 3- safety factor; h r- height of the lamp suspension above the working surface, m.
Artificial lighting can be general(all production premises are illuminated by the same type of lamps, evenly located above the illuminated surface and equipped with lamps of the same power) and combined(to general lighting, local lighting of work areas is added by lamps located near the apparatus, machine, instruments, etc.). Using only local lighting is unacceptable, since the sharp contrast between brightly lit and unlit areas tires the eyes, slows down the work process and can cause accidents.
According to their functional purpose, artificial lighting is divided into: working, duty, emergency.
Work lighting mandatory in all rooms and illuminated areas to ensure normal work of people and traffic flow.
Emergency lighting included outside working hours.
Emergency lighting is provided to ensure minimum illumination in the production area in case of sudden shutdown of working lighting.
In modern multi-span one-story buildings without skylights with one side glazing, natural and artificial lighting (combined lighting) is used simultaneously during the daytime. It is important that both types of lighting are in harmony with one another. Lighting devices make up the largest group of electrical appliances in every home. Light sources are an important element of everyday life.
Sources of artificial lighting. Their advantages and disadvantages
All modern lamps can be classified according to three main characteristics: the type of base, the method of producing light and the voltage from which they operate. Let's start with the most important thing - the method of obtaining light flux. The ability of the lamp to consume a certain amount of electrical energy fully depends on it. Let's take a closer look at some of the features of these lighting lamps.
Incandescent lamps
Incandescent lamps (Fig. 1) belong to the class of thermal light sources. Despite the introduction of more technologically advanced types of lamps, they remain one of the most popular and cheapest light sources, especially in the household sector.
The action of these lamps is based on heating the coil by current passing through it to a temperature of 3000 degrees. The bulbs of lamps with a power of 40 W or more are filled with inert gases - argon or krypton. Household lamps range from 25 to 150 watts. Lamps with a power of up to 60 Watts with a reduced base are called minions. You can check the serviceability of the lamp with a tester; the spiral must have a certain resistance. A lamp with an incandescent lamp has only two possible malfunctions: 1. The lamp has burned out 2. There is no contact in the electrical wiring, as a result of which no voltage is supplied to the base.
Advantages: Simple in design, reliable, do not have additional devices when turned on, practically do not depend on the ambient temperature, ignite instantly.
Flaws: They do not have a very long service life, about 1000 hours.
Fluorescent lamps
Fluorescent lamps (Fig. 2) refer to low pressure gas discharge lamps. They can be of various shapes: straight, tubular, curly and compact (CFL). The diameter of the tube is not related to the power of the lamp, which can reach up to 200 W. Tubular lamps have two-pin base types depending on the distance between the pins: G-13 (distance - 13 mm) for lamps with a diameter of 40 mm and 26 mm and G-5 (distance - 5 mm) for lamps with a diameter of 16 mm.
Compact fluorescent lamp (CFL) (Fig. 3)- a fluorescent lamp that has a curved bulb shape, which allows it to be placed in a small lamp. Such lamps can have a built-in electronic choke (ECG) and can be of different shapes and different lengths. They are used either in special types of lamps or to replace incandescent lamps in conventional types of lamps (lamps with a power of up to 20 W, which are screwed into a threaded socket or through an adapter).
Fluorescent lamps require the operation of a special device - a ballast (choke). Most foreign lamps can work with both conventional (with a choke) and electronic ballasts (EPG). But some of them are intended only for one type of ballast.
Lamps with electronic ballasts have the following advantages: the lamp does not flicker, lights up better, does not make noise (noise from the throttle), is lighter in weight, saves energy (power losses in electronic ballasts are much lower than in ballasts).
By changing the types of phosphor, you can change the color characteristics of the lamps. The letters included in the name of fluorescent lamps mean:
L - luminescent, B - white, TB - warm white, D - daylight, C - with improved color rendering. The numbers 18, 20, 36, 40, 65, 80 indicate the rated power in watts. For example, LDTs-18 is a fluorescent lamp, daytime, with improved color rendering, with a power of 18 W.
A lamp with fluorescent lamps works as follows (Fig. 4) - a tubular lamp is filled with argon and mercury vapor. The starter is necessary to start the lamp, you need to warm up the electrodes for a short time, the current flowing through the inductor and the starter increases significantly, heats the bimetallic plate of the starter, the lamp electrodes warm up, the starter contact opens, the current in the circuit decreases, a short-term high voltage is formed on the inductor, its accumulated There is enough energy to break through the gas in the lamp bulb. Next, the current flows through the inductor and the lamp, with 110 Volts falling on the inductor and 110 Volts on the lamp. Mercury vapor, using a phosphor, creates a glow that is perceived by the human eye. The inductor consumes almost no energy; the energy it takes during magnetization is almost completely returned during demagnetization, while the wires are uselessly loaded; to unload the network, capacitor C is used. Energy exchange occurs not between the network and the inductor, but between the inductor and the capacitor. The presence of a capacitor reduces the efficiency of the lamp; without it the efficiency is 50-60%, with it - 95%. The capacitor, which is connected in parallel with the starter, is used to protect against radio interference.
A malfunction of a fluorescent lamp may consist in a breakdown of the electrical contact in the lamp circuit or in the failure of one of the lamp elements. The reliability of the contacts is checked by visual inspection and testing by a tester.
The performance of the lamp or ballasts is checked by sequentially replacing all elements with known good ones.
Typical malfunctions of lamps with fluorescent lamps
|
Malfunction |
Remedy |
|
|
Protection is triggered when the lamp is turned on |
1. Breakdown of the compensating capacitor (from radio interference) at the lamp input. 2. Short circuit in the circuit behind the machine. |
1. Replace the capacitor. 2. Check the voltage at the contacts of the cartridges and starter. 3. Replace the lamp with a working one. 4. Check the integrity of the lamp spirals. |
|
The lamp does not light up. |
There is no voltage on the lamp socket on the mains side, the mains voltage is low. |
Check with an indicator or tester the presence and value of the supply voltage. |
|
The lamp does not light up, there is no glow at the ends of the lamp. |
1. Poor contact between the lamp pins and the socket contacts or between the starter pins and the starter holder contacts. 2. Lamp malfunction, broken or burnt coils. 3. Starter malfunction - the starter does not close the filament circuit of the lamp electrodes. 4. Malfunction in the electrical circuit of the lamp. 5. Throttle is faulty. |
1. Move the lamp and starter to the sides. 2. Install a known-good lamp. 3. If there is no glow in the starter, replace the starter. 4. Check all connections in the electrical circuit. 5. If no broken wires, broken contact connections or errors in the electrical circuit are detected, then the inductor is faulty. |
|
The lamp does not light up, the ends of the lamp glow. |
The starter is faulty. |
Replace starter. |
|
The lamp flashes but does not light up, there is a glow at one end. |
1. Errors in the electrical circuit. 2. A short in the electrical circuit or socket that may short out the lamp. 3. Closing the terminals of the lamp electrodes. |
1. Remove and insert lamps, swap ends. If the previously non-luminous electrode glows, then the lamp is working. 2. If there is no glow at the same end of the lamp, check whether there is a short circuit in the socket on the side of the non-luminous electrode. 3. If no short circuit is detected, check the wiring diagram. 4. Replace the lamp |
|
The lamp does not blink or light up; there is a glow at both ends of the electrodes. |
1. Error in the electrical circuit. 2. Starter malfunction (breakdown of the capacitor to suppress radio interference or sticking of the starter contacts). |
Replace starter. |
|
The lamp blinks and does not light up |
1. The starter is faulty. 2. Errors in the electrical circuit. 3. Low mains voltage. |
1. Check the network voltage with a tester. 2. Replace the starter. 3. Replace the lamp. |
|
When the lamp is turned on, an orange glow is observed at its ends, after a while the glow disappears and the lamp does not light up. |
The lamp is faulty, air has entered the lamp |
Lamp needs to be replaced |
|
The lamp turns on and off alternately |
Lamp failure |
1. The lamp needs to be replaced. 2. If flashing continues, replace the starter. |
|
When the lamp is turned on, the spirals of its electrodes burn out. |
1. Inductor malfunction (insulation or turn-to-turn short circuit in the winding is broken). 2. There is a short circuit to the body in the electrical circuit. |
1. Check the electrical circuit. 2. Check the insulation of the wires. 3. Check the electrical circuit for a short to the lamp body |
|
The lamp lights up, but after a few hours of operation, blackening of its ends appears. |
1. Short circuit to the lamp body in the electrical circuit. 2. Throttle malfunction. |
1. Check for a short to the housing, check the wiring insulation. 2. Using a tester, check the value of the starting and operating current; if these values exceed normal values, replace the inductor. |
|
The lamp lights up, when it burns, the discharge cord begins to rotate and moving spiral and serpentine stripes appear |
1. The lamp is faulty. 2. Strong fluctuations in network voltage. 3. Poor contact in connections. 4. The lamp covers the magnetic field lines of the inductor leakage. |
1. The lamp needs to be replaced. 2. Check the mains voltage. 3. Check contact connections. 4. Replace the throttle. |
Advantages: Compared to incandescent lamps, they are more economical and durable, and have good light transmission. The service life is up to 10,000 hours for imported lamps and up to 5000-8000 hours for domestic ones. Convenient to use where the lamp is on for many hours.
Flaws: At temperatures below 5 degrees, they are difficult to ignite and may burn more dimly.
DRL gas discharge lamps
DRL lamps(mercury arc with phosphor (Fig. 5.6), these are high-pressure discharge lamps. Thanks to additional electrodes and resistors placed in the bulb, the lamp does not need an ignition device, is connected to a network with an inductive ballast and is ignited directly from a voltage of 220 Volts, a capacitor is needed to reduce the current.
After turning on the lamp, it lights up, the luminous flux created by the lamp gradually increases, the combustion process lasts 7 - 10 minutes. When the voltage disappears, the lamp goes out. It is impossible to light a hot lamp; it needs to cool completely; after turning it off, it can only be re-lit after 10-15 minutes. They come in power from 80 to 250 watts.
Repair of lamps with DRL lamps consists of identifying the failed element and replacing it with a known good one.
Advantages: significantly more economical than incandescent lamps, insensitive to temperature changes, so they are convenient to use for outdoor lighting, service life up to 15,000 hours.
Flaws: low color rendering, pulsation of light flux, sensitivity to voltage fluctuations in the network.
Halogen lamps
Halogen incandescent lamps(Fig. 7) belong to the class of thermal light sources, the light radiation of which is a consequence of the heating of the lamp coil by the current passing through it. Filled with a gas mixture containing halogens (usually iodine or bromine). This gives the light brightness, saturation, and can be used in point light sources.
It is better to use lamps from well-known companies - halogen lamps emit ultraviolet rays, which are harmful to the eyes. Lamps from well-known companies have a special UV-resistant coating.
If a malfunction occurs, measure the voltage at the lamp base; if the voltage is normal, replace the lamp. If there is no voltage on the lamp base, there is a malfunction in the transformer or in the contact part of the electrical fittings.
Advantages: Service life 1500-2000 hours, have stable luminous flux throughout the entire service life, smaller bulb sizes compared to incandescent lamps. With the same power as an incandescent lamp, the light output is 1.5-2 times greater.
Flaws: Changes in the mains voltage are undesirable; when the voltage decreases, the temperature of the filament decreases and the service life of the lamp decreases.
Energy-saving lamps
Energy saving lamps (Fig. 8) are intended for use in lighting fixtures of residential, office, commercial, administrative and industrial premises, in decorative lighting installations.
They can be used in any lamp as a substitute for incandescent lamps. Energy-saving lamps are a type of low-pressure discharge lamps, namely compact fluorescent lamps (CFLs).
The power of energy-saving lamps is approximately five times less than that of incandescent lamps. Therefore, it is recommended to choose the power of energy-saving lamps based on a 1:5 ratio to incandescent lamps.
The main parameters of such lamps are color temperature, base size and color rendering coefficient. Color temperature determines the color of the energy-saving lamp. Expressed on the Kelvin scale. The lower the temperature, the closer the color of the glow is to red.
Energy-saving lamps have different glow colors - white warm light, cool white, daylight. It is recommended to choose the right color based on the interior of the apartment or house and the visual characteristics of the people who are there. Cool white light is designated 6400K. This type of lighting is bright white and is better suited for office spaces. Natural white light is designated 4200K and is close to natural light. This color can be suitable for a children's room and living room. White warm light is slightly yellowish and is designated 2700K. It is closest to an incandescent lamp, better suited for relaxation, and can be used in the kitchen and bedroom. Most people choose a warm color for their apartment.
If flickering appears in an energy-saving lamp, this indicates a malfunction of the device; the lamp is either loosely screwed in or faulty and must be replaced.
Advantages: Lasts 8 times longer than conventional incandescent lamps, consumes 80% less electricity, produces 5 times more light for the same energy consumption, can work continuously in places where lighting is required throughout the day, is less sensitive to shaking and vibrations, heat up slightly, do not buzz or flicker.
Flaws: Warm up slowly (about two minutes), cannot be used in open street lamps (do not work at temperatures below 15 degrees C), cannot be used with dimmers and motion sensors.
LED bulbs.
LED bulbs(Fig. 9) are another new generation light source.
LEDs serve as the light source in such lamps. An LED emits light when electric current passes through it.
LED main lighting lamps consist of: a diffuser, an LED or a set of LEDs, a housing, a cooling radiator, a power supply, and a base. The cooling radiator is of great importance, since the LEDs and power supply get hot. If the radiator is small or poorly made, then such lamps fail faster (usually the power supply fails). The power supply converts 220V alternating voltage into direct current to power the LEDs.
Available in GU5.3, GU10, E14, E27 cartridges. Lamps are available in soft warm light (2600-3500K), neutral white (3700-4200K) and cool white (5500-6500K). There are LED bulbs that can be dimmed (using a dimmer for incandescent bulbs), but they are more expensive.
Advantages: Economical (electricity costs are 10 times less than incandescent lamps), long service life (20,000 hours or more), safe components are used in production (do not contain mercury), resistant to voltage surges, do not require heating (unlike energy saving lamps).
Flaws: Quite a high price, LEDs gradually lose brightness, cannot work at temperatures above 100 degrees C (ovens, etc.).
ROSTOV STATE UNIVERSITY OF COMMUNICATIONS
Department: “Life Safety”
Calculation and graphic work
in the discipline: “Life Safety”
On the topic: “Natural lighting”
Task 4, option 10
Completed
group student
Rashnikov A.V.
teacher
Pavlenko Yu.V.
Mineral water
1. Lighting characteristics and units of measurement 3
2. Advantages and disadvantages of natural lighting. General lighting provisions. 6
3. Types of natural lighting 8
4. The principle of rationing natural light 10
5. Calculation of side one-sided natural lighting in the production area. 15
5.1 Determination of the normalized value of K.E.O. 15
5.2 Determination of the total area of light openings. 16
5.3 Determining the number of light openings 17
6. Plan and section of the room indicating accepted light openings 19
References 19
1. Lighting characteristics and units of measurement
To characterize light, certain lighting concepts and quantities are used.
We often observe phenomena that are associated with the action of energy sources located at a considerable distance. Thus, we feel the energy of the Sun in the form of heat and light, despite the fact that it is located at a great distance from the Earth. In such cases, energy transfer occurs through radiation. This energy is called radiant. It propagates in space in a straight line in the form of electromagnetic oscillations called electromagnetic waves. To measure wavelengths λ in the visible part of the spectrum, fractional values of the basic unit of length - the meter are used: 1 micron (µm) is equal to 10 -6 m; 1 nanometer (nm) is equal to 10 -9 m; 1 angstrom (A) is equal to 10 -10 m.
The power of radiant energy is called radiant flux, which is the amount of radiant energy transferred per unit time. It is measured in watts (W). The human eye perceives radiant energy within wavelengths from 380 to 760 nm. This part of the spectrum of electromagnetic oscillations is called the visible part of the spectrum. Acting on the eye, it causes a sensation of light. The action of individual parts of the visible spectrum at certain ratios is perceived by the eye as white light. These include radiation from daytime scattered light from the sky, sun, etc.
The sensitivity of the eye to radiation of different wavelengths of the visible spectrum is not the same. It is called spectral sensitivity of the eye. The normal human eye is most sensitive to yellow-green radiation, the wavelength of which is 556 nm. The power of radiant energy, characterized by the sensation of light it produces, is called luminous flux. The unit of luminous flux is the lumen (lm). A lumen is the luminous flux emitted by a platinum plate with an area of 0.5305 mm 2 at a solidification temperature of 2042 ° K (Kelvin). To measure large luminous flux values, a kilolumen is used, which is equal to 1000 lm.
The distribution of light flux in space is characterized by its spatial density, determined by the amount of light flux per unit solid angle. The spatial density of the luminous flux is called by the power of light. The unit of luminous intensity is taken to be the spatial density of the luminous flux when, within a solid angle of 1 degree (steradian), a luminous flux of 1 lm is uniformly distributed. This unit of light is called a candle (sv). Steradian is a unit of measurement of solid angle. It is equal to the solid angle cutting out a sphere of radius on the surface R area numerically equal to the square of the radius of a given sphere r 2 .
The surface density of the incident light flux is called illumination. It is characterized by the amount of luminous flux per unit surface. If the incident luminous flux is uniformly distributed on the surface, then the illumination E equal to
Where F pad - luminous flux in lm;
S is the surface area on which the luminous flux falls.
The illumination created by a uniformly distributed luminous flux of 1 lm on a surface of 1 m2 is called lux (lx). Lux is taken as a unit of illumination. The illuminated object will be the better visible, the more light intensity each surface element receives.
The ratio of the intensity of light emitted in the direction under consideration to the area of the luminous plane is called brightness. By measuring the luminous intensity in candles and the projection of the luminous surface in square meters, we obtain the brightness expressed in candles per 1 m 2. This unit is called a nit (nt). A uniformly luminous flat surface has a brightness of 1 nit, emitting light in a direction perpendicular to it with an intensity of 1 light per 1 m 2.
Thus, the main light quantities are luminous flux, luminous intensity, illumination and brightness.
2. Advantages and disadvantages of natural lighting. General lighting provisions.
In railway transport and transport construction, lighting is of particular importance in ensuring the safety of train traffic and creating healthy, highly productive working conditions, and to a large extent natural lighting. Clear visibility and discrimination of signals (traffic lights, semaphores, etc.), instrument readings on control panels are possible only with sufficient illumination of the object in question, correct placement of light sources in relation to the illuminated object and objects in relation to the eye of the worker.
The adaptation of the eye to different levels of brightness in the field of view is called adaptation. Adaptation allows people to navigate well in bright light and in conditions of almost complete darkness. The time it takes for the eye to readapt from one brightness level to another varies. Adaptation to high brightness (light adaptation) occurs quickly, in contrast to adaptation to low brightness (dark adaptation), which takes longer.
An object can be detected if there is some difference in the brightness of the observed object and the background against which it is viewed. The greater the contrast, the better the subject is visible against the background. The ability of the eye to perceive the smallest contrasts is called contrast sensitivity. The lower the contrast perceived by the eye, the higher its contrast sensitivity. As the background brightness increases, contrast sensitivity also increases. However, it should be noted that the increase in contrast sensitivity occurs only up to a certain value of background brightness, after which it gradually decreases.
The accuracy of visual work is also determined resolving power normal eye, which is equal to one. The sensitivity of the eye to distinguishing small details will be greater, the lower the resolving power of the eye.
The reciprocal of the resolving power of the eye is called visual acuity. Visual acuity equal to one will be with the resolving power of the eye also equal to one. With a resolving power of two, visual acuity will be 0.5.
Visual performance (visual acuity, contrast sensitivity, speed of discrimination, etc.) is determined by the following factors: the degree of brightness of the objects in question, the presence of contrast between the object and the background, the angular size and time of observation of the object. Improvement of the visual functioning of the eye is ensured by increasing the illumination of working surfaces with the obligatory elimination of glare from the field of vision.
3. Types of natural lighting
Daylight- lighting of premises with direct or reflected light penetrating through light openings in external enclosing structures. Natural lighting should be provided, as a rule, in rooms with constant occupancy. Without natural lighting, it is allowed to design certain types of industrial premises in accordance with the Sanitary Standards for the Design of Industrial Enterprises.
The following types of natural indoor lighting are distinguished:
lateral one-sided - when the light openings are located in one of the external walls of the room,
Figure 1 - Lateral one-way natural lighting
side - light openings in two opposite external walls of the room,
Figure 2 - Lateral natural lighting
upper - when lanterns and light openings in the covering, as well as light openings in the walls of the height difference of the building,
combined - light openings provided for side (top and side) and overhead lighting.
Ministry of Education and Science of the Russian Federation
Federal State Budgetary Educational Institution of Higher Professional Education
Ulyanovsk State Technical University
Department of Safety and Industrial Ecology
Laboratory work No. 16
Completed:
Student of group RTd-31
Abramov A.V.
Kudrin A.N.
Ulyanovsk, 2012
Goal of the work:
1.1. Master methods for assessing the qualitative and quantitative characteristics of lighting and the effectiveness of a given lighting installation for a specific job.
1.2. Familiarize yourself with systems and types of lighting, with the characteristics and criteria for choosing light sources and lamps for certain jobs and premises.
1.3. Study the principles of rationing artificial, natural and standardized lighting of premises for specific visual work, taking into account all influencing factors.
1.4. Master methods for calculating artificial, natural and standardized lighting of premises (lighting calculations).
1.5. Learn to work with basic lighting measuring instruments: lux meter, visibility meter, etc.
Theoretical part.
1.Name the factors influencing the choice of standard artificial working lighting E.
In the current SNiP P-4-79 (with amendments and additions in 1986), all visual work, depending on the size of the object of discrimination, is divided into 8 categories.
Object of distinction– the item in question, its individual part or defect that needs to be distinguished during the work process (line, mark, stain, scratch, etc.).
Discharge characterizes the accuracy of visual work.
Background- a surface adjacent directly to the object of discrimination on which it is viewed.
The contrast of the object with the background is considered high at K > 0.5 (object and background differ sharply in brightness), average at K< 0,2 (отличается мало).
2. How is the number of lamps for lighting a room determined?
Number of lamps
3. How many steps are there in the light scale? What are the maximum and minimum values of e?
Scale of normalized illumination values lux (31 steps):
0,2; 0,3; 0,5; 1; 2; 3; 5; 7; 10; 20; 30; 50; 75; 100; 150; 200; 300; 400; 500; 600; 750; 1000; 1250; 1500; 2000; 2500; 3000; 3500; 4000; 4500; 5000.
E min =0.2, E max =5000;
4.Name the advantages and disadvantages of the general lighting system. Where is it used?
General lighting in a combined system ensures uniform brightness distribution, for which its share of illumination can be 10% or higher than the norm for combined lighting.
General artificial lighting is usually apply for lighting rooms with low-precision and rough visual work, i.e. with grades 5-7. For work of medium and high precision, it is used if there are justifications made by the designer (for example, the impossibility or inexpediency of installing local lighting in a combined system).
5.Name the advantages and disadvantages of ln.
In incandescent lamps(LN) light is created by an incandescent body, heated as a result of the passage of electric current through it. LNs can be vacuum and gas-filled (filled with inert gas: argon, krypton).
The advantages of LN include:
Almost complete independence from environmental conditions, including temperature;
Operability even with significant deviations of the network voltage from the nominal one;
Wide range of powers and voltages;
Direct connection to the network without additional devices;
Simplicity of design and ease of use;
Relatively small dimensions;
No pulsation of the light flux due to the high thermal inertia of the filament;
Low cost.
The disadvantages of LN are: predominance of yellow-red rays in the spectrum, low luminous efficiency compared to LL and RL (in modern types of LL it has been significantly increased), high (blinding) brightness of the filament, limited combustion duration.
Measuring illumination using a luxmeter.
Photoelectric lux meter type Yu16 is designed to measure illumination (in lux) created by incandescent lamps, fluorescent lamps and natural daylight. The device has three main measurement limits: 25, 100 and 500 lux and three additional ones: 2500; 10,000 and 50,000 lux, obtained using a porcelain absorber placed on a photocell (in the case of measuring high artificial and daytime natural light).
Rice. 8.1 Schematic diagram of a lux meter.
Working conditions: ambient temperature from 10° to 35°C, relative humidity up to 80%.
The main error does not exceed ± 10 - 15% of the measured value. The settling time of the moving part is no more than 5 seconds, accuracy class 1.0.
Operating principle of the device Fig. 8.1 is based on the phenomenon of the photoelectric effect, when when the surface of a selenium photocell is illuminated, a current arises in a closed circuit, deflecting the moving part of the magnetoelectric meter I. The magnitude of the current and, consequently, the deflection of the meter needle is proportional to the illumination on the working surface of the photocell.
On the body there are two clamps for attaching a photocell and a measurement limit switch.
Before measuring you must:
position the device horizontally, taking into account that installing it near live wires that create strong magnetic fields, near a heat source (above 40 ° C) and in humidity areas (more than 80%) is unacceptable;
check the position of the arrow, which should be at the zero scale mark when the photocell is turned on. In case of deviation, it can be set to the zero position using a screw located on the front side of the device (the photocell is darkened);
connect the photocell to the meter, observing the polarity indicated on the terminals (+) and (-).
Measuring artificial illumination indoors should begin with the switch position at the limit of 500 lux, and only with a small deviation of the arrow (less than 10 divisions) is it advisable to move the switch to the limit of 100 lux or even lower. In the presence of illumination of more than 500 lux, measurements are carried out using an absorber mounted on a photocell.
Measuring natural light indoors and outdoors must be done with an absorber with the switch position at the limit of 500 lux.
If the arrow deviates by less than 10 divisions, it is allowed to move the switch to lower limits, and if the value is 500 lux, it is allowed to remove the absorber when the switch is positioned at the limit of 500 lux.
When measuring, a photocell is brought into the specified area at the required angle and a reading is made on the scale. If the illumination created by fluorescent lamps is measured, the luxmeter readings are multiplied by correction factors:
0.9 for LD lamps; 1.1 for LB lamps; when using absorber at 100.
Measuring natural light entails the introduction of a correction factor equal to 0.8.
The device must be handled with extreme care. It is prohibited: to move the photocell curtain; bring the photocell to the lamp; contaminate the surface of the photocell and absorber and touch it; disassemble the absorber; subject to shocks.
When measuring illumination, it is necessary to record in the protocol not only the measured levels, but also indicate the area and height of the room, the type of lamp, the height of its suspension or installation above the work surface, the number, type and power of lamps, the brightness of the walls, ceiling and equipment.
The nature of visual work, date, time of day is indicated.
When measuring natural light, the number and size of windows are indicated. A sketch of the room or workplace is given, and the points where illumination was measured are noted.
Artificial light sources can be compared with each other according to the following parameters: rated supply voltage U (V), electric power of the lamp P (W), luminous flux emitted by the lamp F (lm), maximum luminous intensity J (cd); light output
Еv = Ф/Р (lm/W),
those. the ratio of the luminous flux of the lamp to its electrical power; lamp life and spectral composition of light.
Incandescent lamps are widely used in industry. Their advantages: ease of use, ease of manufacture, low inertia when turned on, the absence of additional starting devices, reliability of operation under voltage fluctuations and under various meteorological environmental conditions. The disadvantages of incandescent lamps include: low luminous efficiency (for general purpose lamps Ev = 7...20 lm/W), relatively short service life (up to 2.5 thousand hours), the predominance of yellow and red rays in the spectrum, which is not Their spectral composition differs greatly from sunlight.
Halogen lamps - incandescent lamps with an iodine cycle have become widespread. Their advantages over incandescent lamps are increased luminous efficiency (up to 40 lm/W), due to an increase in the temperature of the filament. The service life of the lamp also increases to 3 thousand hours, due to the fact that tungsten vapor evaporating from the filament combines with iodine and again settles on the tungsten spiral, preventing sputtering of the tungsten filament. Halogen lamps have a radiation spectrum closer to natural.
The main advantage of gas-discharge lamps over incandescent lamps is their high luminous efficiency of 40...110 lm/W. They have a significantly longer service life, up to 8...12 thousand hours. From gas-discharge lamps you can obtain a luminous flux of any desired spectrum by selecting inert gases, metal vapors, and phosphors accordingly. Based on the spectral composition of visible light, fluorescent lamps (LD), daylight with improved color rendering (CLD), cool white (LCW), warm white (WLT) and color white (WL) are distinguished. The main disadvantage of gas-discharge lamps is the pulsation of the light flux, which can cause a stroboscopic effect, which distorts visual perception. The disadvantage of gas-discharge lamps is the long burn-up period, the need to use special starting devices to facilitate ignition of the lamps, and the dependence of performance on the ambient temperature. Discharge lamps can cause radio interference, the elimination of which requires special equipment.
The advantages of LED lamps are as follows: high luminous efficiency, long service life up to 50 thousand hours, can have different spectral characteristics without the use of filters, safety of use, small size, high strength, absence of mercury vapor, low ultraviolet and infrared radiation, low heat generation, resistance to vandalism. The disadvantages of these lamps include: high price, the use of voltage converters, high pulsation coefficient of the light flux without a smoothing capacitor, the spectrum is slightly different from that of the sun.
According to the distribution of the luminous flux in space, lamps of direct, predominantly direct, diffused, reflected and predominantly reflected light are distinguished. Depending on the design, luminaires are distinguished as open, protected, closed, dust-proof, moisture-proof, explosion-proof, explosion-proof.