Luminous Flux is what?

The power of visible light radiation, which is estimated by the sensation of the human eye and measured in lumens, is the light flux. This is the energy that any light source gives.

Wavelength

Energy source of light transmits by means of radiated electromagnetic waves. The luminous flux is the velocity of them, which gives information about the power of the glow of a particular source. The energy of light waves is perceived by the human eye in different ways. The wavelength of 0.55 μm in green color is perceived much stronger than in the red with a length of 0.63 μm. In the range of ultraviolet and infrared radiation, our eyes are powerless.

That is why the wavelength is so important for the characteristics of the light flux. Taking into account the susceptibility to the eye, summing the wavelengths, we obtain a normalized value. The luminous flux is the norm of the power of that radiant energy, which is estimated at the expense of the light sensation. Choosing for himself the source of light energy, a person conforms to its equivalent capacity. For example, if you need to replace the incandescent light bulbs. In this case, you need to recalculate the luminous flux.

How to do it

The luminous flux is the main indicator on this path. With the previous two-volt incandescent lamp, it was 250 lm. Precisely the same light flux of LED lamps can be provided by two to three watts, and luminescent by five to seven. Hence, the benefit of LED lamps is more than obvious.

Let's say we need light sources with a capacity of 400 lm. The incandescent lamp should be forty-watt, the fluorescent lamp can have from ten to thirteen watts, and the LED lamp - only four or five. Or, for example, we need a powerful light flux of lamps - in 2500 lm. The incandescent lamp can not in this case be less than two hundred-watt, the luminescence is only sixty to eighty watts, and the LED even less is only twenty-five or thirty.

What are the lamps

The size of the power consumption of any lamp is measured in watts (watts). In everyday life, for example, LED lamps from one to ten watts are used, and for outdoor lighting they need much more powerful - there are over a hundred watts. But it is necessary to know that the power of a lamp is characterized only by the rate of energy consumption, the concept of the strength of light it does not answer.

Here, one or another source can only describe a unit of light flux, which is an absolutely different parameter. It is measured not in watts, but in lumens. Not every lamp manufacturer has these parameters correctly specified. For example, a note on the package: a luminous flux of 280 lumens for a four-watt LED lamp, equivalent to a fifty-incandescent bulb. We look at the table: in the latter the luminous flux is not 280 at all, but all 560 lumens should be. How so?

Calculations

The unit of the light flux of lumens is equal to the flux emitted by an absolutely black body with an area of 0.5305 mm ² at a very high temperature of 1773 ° C, with it solidifying platinum, for example. The strength of light is the density of the light flux in the spatial sense, it is important to consider how the light flux correlates with the magnitude of the solid angle (and the solid angle is the part of the space where all the rays converge). So: a unit of the power of light is not lumen, but candela.

What is illumination? This can be called the surface density of the light flux, which falls on a surface equal to the ratio of the light flux itself to the dimensions of the illuminated surface, where it is evenly distributed. Illumination also has its own unit of measurement, and this again is not lumen. And not even candela. This suite (lux). What will be one lux if the luminous flux is equal to one lumen, distributed evenly over an area of one square meter? And here: 1 Лк = 1 Лм / 1м ² .

Brightness and luminosity

Light streams can be of different brightness and luminosity (luminosity). Brightness is the equality of the surface density of the force of light and its ratio to the area projected by the luminous surface on a plane perpendicular to this direction. The unit of brightness is considered to be one candel per square meter (1 cd / m ² ).

Luminosity (or luminosity) is the density of the light flux emitted by the illuminated surface. It is always equal to the light flux relative to the area of this surface. Luminosity also has its own unit, it is 1 lm / m ² .

Uniform lighting

The coefficient of use of the light flux is a method that makes it possible to calculate the uniformity of illumination of all surfaces horizontally, irrespective of the type of luminaires. Its essence lies in the fact that the coefficient is calculated for each room, taking into account its main parameters and properties of light reflection of finishing materials. This is a fairly time-consuming calculation, not very accurate, but this method is widely used in the planning of indoor lighting.

The room volume always has some kind of enclosing surfaces that will reflect the light stream coming from the sources. These are walls, ceiling, floor, furniture or equipment in the room. All surfaces have different reflection coefficients, with a higher value or less. Calculate the number of lighting devices, not taking into account the reflected flows, is possible only with large errors.

Calculation part

First choose a lighting system and light sources, select the types of lamps for a particular room - a living or working, and then the calculation is made. Its purpose is to determine the number of lamps. The calculation sequence can be performed according to this scheme:

1. Choice of lighting system.

2. Substantiation of normalization in the illumination of this object.

3. Choosing the most economical light source.

4. Choosing a rational type of lamp.

5. Estimation of the factor of the reserve of illumination and the coefficient of its unevenness.

6. Estimation of the reflection coefficient of the surfaces in the room.

7. Calculation of the index of the room.

8. Determination of the coefficient in the use of the light flux.

9. Calculation of the number of lamps that will provide the required illumination of the object.

10. Sketch on the arrangement of luminaires using the room plan (specify the dimensions).

Lighting system

It is especially difficult to calculate working lights, since it is often combined. For example, in local workshops only local lighting is prohibited by law. Select the lighting system according to the smallest size of the object of discrimination, that is, guaranteeing the accuracy of all visual works that will be performed indoors.

Here the norms are valid: works from the first to the sixth digits are performed only with a combined lighting system. These are mechanical, instrumental, assembly and similar shops. Only in industries such as galvanic or foundry can a general lighting system be used. Therefore, choose the system and the norms of illumination at the same time.

Normalized illumination

Artificial lighting by quantitative and qualitative indicators is determined in strict accordance with the established and constantly applicable standards for the given production and type of work.

The quantitative characteristic of illumination is taken at the lowest for each working surface, depending on the discharge of visual works, the contrast and the background of the object in the given lighting system. The discharge is determined by the size of the object (part), its part or the minimum defect on it, which the worker will have to detect and distinguish in his activity. Qualitative indicators of illumination are an indicator of blinding and a pulsation coefficient.

Light sources: pros and cons

How to determine the parameters for choosing an economical and at the same time environmentally friendly light source? The solution can be influenced by many factors, such as: planning decision, architectural, building parameters, air environment and its condition, economic considerations and, of course, design. The designer designing the lighting always compromises, considering many parameters in the calculations.

For example, incandescent lamps are not too economical, they do not have a very high light output, the radiation spectrum is distorted, they become very hot during operation and quickly fail. However, their cost is very low, they are the easiest to operate in operation, and therefore it is quite possible to recommend incandescent lamps for rooms where people temporarily stay, household and so on. Luminescent also have light output simply excellent, long service life, excellent color rendition, no heating. But such lamps are expensive and require professional service. The starting equipment of fluorescent lamps is very complicated, they sometimes flash and rustle, and their utilization is problematic.