What are the Important Parameters of LED Lights?

LED lamps have many parameters. Due to the different nature of lighting, the focus of these parameters will be different.
The most common parameters that change in general lighting systems are power, luminous flux and color temperature. As a professional lighting system: it is necessary to pay attention to the light distribution curve and color temperature in applications such as road lighting. The production line, factory lighting, should pay attention to the color rendering index to see the accuracy of the produced object. Consideration should be given to the power factor when installing high-power lamps in a large area. Below is a brief introduction to these indicators.

Strength

Power is the most primitive and common parameter for all devices. The power indicator only showed how much electricity the lamp could consume, but it has now become almost the only indicator other than the lamp type. When people talk about lamps and lanterns, they always talk about “15w bulb”, “120W street light” etc. Few people talk about other indicators. The main reason for this is that the power parameter is easily understood and accepted by everyone, and the power and lighting effect are basically proportional in the same series of lamps. That's why power rose into a comprehensive index in everyone's minds rather than just showing how much power was consumed.

Light flow(Luminous Flux)

Luminous flux is the basic indicator of a light source that shows how much light energy the light source emits. The original definition of luminous flux means that when a standard candle is placed in a circular area two meters in diameter, the light passing through this sphere is one lumen per square meter and is written in lm.

As a luminous flux index, there are generally two methods of marking: one is marking the absolute value. For example, if the luminous flux of a 120W street lamp is 12000 lm, it can be directly marked with 12000 lm. However, this does not reflect how much electricity is consumed to extract light energy, so many lamps use the format lm/W to reflect the efficiency of electricity use.
This form of labeling is called the “light effect” indicator. In the example above, the luminous efficiency of the street lamp can be expressed as 100 lm/W. This is a relative parameter, the larger the value, the higher the power usage rate.

There is also an indicator called "lamp efficiency", which expresses the rate of use of the lamp from the light source. For example, if the light flux of an LED light source is 1000 lumens, install it in a street light and then do a general test. The light flux is only 900, then the efficiency of the lamp is 90%. This indicator is generally not used much and is easy to compare with lm/W.

Some manufacturers deliberately ignore the efficiency of the lamp and mark the light effect of the light source directly as the entire light effect.


Soli Lighting AK Series 1200W 150000lm


Color temperature and color rendering index

The more popular meaning of color temperature refers to the high temperature color of an object. For example, the temperature after burning iron red is the color temperature corresponding to that color. As the temperature rises, the color of the iron gradually turns yellow, white, and blue. The color with high temperature is called high color temperature, it usually points above 5000K, and the reddish color below 3000K is called low color temperature. The temperature mentioned here is in Kelvin K, not our commonly used degrees Celsius ℃. Its absolute value is as large as Celsius, but the overall coordinate is shifted down by 273.15°C, meaning zero Celsius is equivalent to 273.15K Kelvin.

Kelvin is not below zero, and zero degrees is the limit of low temperature in the universe.

Let's talk about the color rendering index. It refers to the degree of color of the illuminated object when the surface of the object is illuminated with a certain light. The color temperature of the noon sunlight is 5500～6000K. The color of objects seen under the sun is considered natural color, so people define the color rendering index of sunlight as 100.

Many people think that as long as the color temperature of the light source is controlled at 5500～6000K, the color rendering index can reach 100. This is actually a misunderstanding. The International Illumination Institute made a "chromaticity diagram" in 1931. The actual situation is when the color temperature of the lamp beads is 5564K, the color rendering index can only be 75. This is because there is a problem with its composition. light.

It can be seen from the spectrum that the LED lamp beads have obvious blue peaks. The position of the white area on the chromaticity diagram is different, which causes the color rendering index to change. Simply put, even if the light source is at the same color temperature, more or less light of a particular color will also affect the color rendering index.

There is no need to pursue an excessively high color rendering index in a general lighting environment. For example, car lamps and street lamps should focus on color temperature, while production shops or painting rooms should focus more on the color rendering index.

Light distribution curve

The light emitted by the light source is "free and diffuse" and in most cases cannot meet people's lighting effects requirements. This requires completion and adjustment of these lights to make them work better. Such confinement and termination of light is called "light scattering" (light scattering will inevitably lead to loss of luminous flux).

For example, the flashlight concentrates the light forward, and the most common examples of light distribution applications, the old incandescent lamp, adds a lampshade to make the light shine, etc. The figure above is the light distribution curve of the two lamps. The spot on the left is similar to a flashlight, the light is concentrated at a small angle. The street lamp on the right adjusts the light on both sides (commonly known as the flat bat-shaped light distribution curve) to enhance the light slightly further away from the lamp head in a straight line to avoid excessive light under the lamp. This is very important for special lighting places such as streetlights and car lights.

Power Factor

Power factor is an important index specific to AC devices. Due to the presence of capacitive and inductive loads, a large amount of reactive current will be produced in the circuit. Even if utilities won't charge more electricity fees for this reason, they must bear the consequences of increasing the wire diameter investment or the wire heating and voltage drop itself. At present, the country does not have strict requirements for the power factor of low-power electrical appliances, but attention should be paid to the large-scale use in a local area.

In addition to the above indicators, there are also indicators such as brightness and illumination. However, these indicators relate to the illumination distance and reflective properties of the illuminated object and will only be used when designing or evaluating the lighting effect in a particular situation and have no practical meaning as a lamp itself.