Luminous flux for LED lamps
Any lamps, whether LED or incandescent, have a major parameter that determines their power. The unit of measurement is watt (w). But the power of the lamps is only a definition of their electricity consumption. To find out how much light a lamp emits, you need to pay attention to an important parameter - the luminous flux.
Luminous flux determination
Each light source has its own indicator of the luminous flux, information about which must be on the packaging of the product or in the instruction manual. Making high-quality lighting, you need to know that lamp power plays a major role in determining the light flux. But be sure to take into account the light return, measured in lumens. All these parameters are important in terms of energy savings.
According to the laws of physics, the maximum light output of any lamps is 683 Lm / W. During the conversion of electricity into a light beam, losses appear that hinder the achievement of a larger indicator.If we compare conventional incandescent and energy-saving lamps, then the indicator of the first is 12 Lm / W, and the indicator of the second is 60 Lm / W. The highest rate give LED lamps - 70-90 Lm / W. To make it easier to determine the light flux of different light sources, there is a table. It can even make a comparison, for example, LED and ordinary incandescent bulbs.
The table accurately shows the indicator for LED, fluorescent and incandescent lamps, provided that they are new. With the duration of operation of any lamp, the size of its flow decreases. This factor must be considered when arranging the lighting of each room in the room.
There is another factor that impairs the indicator of the flow of light - it is the lamp itself. The size of the losses depends on the quality of the materials from which it is assembled. They can range from 20 to 80%:
- The largest percentage of losses are lighting with energy-saving or conventional incandescent bulbs. Here the whole problem lies in the quality reflector installed in the lamp. While the lamp is lit, the scattering angle is 360about, that is, the flow of light is directed in all directions.The reflector of the lamp directs the flow in one direction, which creates a certain percentage of losses.
- The LED lamp or the lamp has the least losses. Their design consists of LEDs illuminating the space in front of them. Having a flux of luminescence in one direction, the LED lamp does not require the use of an additional reflector. For the direction of the glow on the sides, the LEDs are placed on an inclined plane at different angles or use a diffusing bulb. The most common devices with a scattering angle from 120 to 170about. Their losses are no more than 5% due to the use of focusing lenses and protective pads.
- Many luminaires are equipped with reflex glasses for diffusing light. The quality of their performance also affects the level of flow. Thus, a powerful LED lamp with a poor reflector will give a smaller stream of light than a low-power lighting device without a lens.
Light output of diode light sources
The intensity of illumination of different points in space depends on the intensity of the light. For its measurement there is a unit - candela, abbreviated as cd.The light flux that the lamp emits is calculated as the uniform distribution of the light flux to the solid angle. It is possible to determine the intensity of light with a special device - a luxmeter, taking measurements at different points of the illuminated place. There are many types of LED lighting devices designed for use in various environments. Of these, the most distinguished models for street, home, industrial or office use. An example of the ratio of light output - the power of LED lamps can be seen in the table.
Uniform illumination method
There is such a thing as the coefficient of use of light. It is used to calculate the uniform illumination of the horizontal planes of the surface indoors. This method allows you to calculate the coefficient of illumination of each room separately. It is based on the light reflection of different materials of decoration. The main reflectors of light are the walls, the ceiling and the floor. The secondary reflectors affecting the coefficient are furniture, equipment and other objects in the room.Special attention should be paid to the light reflectance, because its light flux can have the same power with a direct stream of light coming from the lighting device. If this is not paid attention, calculating the coefficient for a particular room, the light background may be violated.
In order to correctly calculate the light flux ratio of any lamps, a table is used with a percentage indication of the reflection of light from the surface of different colors. The darker the surface, the weaker the reflected light flux and the lower the coefficient.
The calculation takes into account the norms of the recommended levels of illumination indicated in the table.
The coefficient of light flow allows you to determine other parameters of luminaires with any light source, be it an LED or an ordinary incandescent lamp:
- calculate the total power of the lamps used to achieve the required standard of illumination, taking into account the preliminary determination of the location of lighting devices, their number and models;
- calculate the location, as well as the number of lighting devices, depending on the models of luminaires and the power of the light sources used.
There are other methods for calculating the illumination, for example, by power density and point method. They require the use of formulas, nomograms, tables and special graphs. This definition of the coefficient is time consuming, but is considered more accurate.