Basic information, concepts - lighting and light sources

Types of power supplies

LED strips and LEDs supplied with low voltage (typ. 12VDC, 24VDC), can be dimmed. 

Switching of sources for LED strips see this article.

Dimming of LED strips see this article.

Power LEDs supplied with rated current (typ. 350, 500, 700, 1000 mA). 

Dimmable with controllable power supply, see module C-DM-0006M-ILED. 

Switching of sources for current-excited LEDs see this article.

Dimming current-excited LEDs see this article.

Compact LED source (incorrectly LED bulb).

Replacement of classic light bulbs, standard threads according to light bulbs, 230VAC power supply, only types that are explicitly designed for this can be dimmed, see this article.

Tubular LED source (incorrectly LED fluorescent lamp)

Replacement of fluorescent lamps, 230 VAC supply, usually cannot be dimmed.

Light bulbs

Optical radiation is created in them when the solid is heated to a high temperature. The advantage is simple installation and maintenance, the disadvantage is the low specific power (a classic bulb with a power input of 25 W has a specific power of about 9 lm / W) and a short average life (about 1000 hours).

They are easily dimmed, see this article.

Halogen bulbs

The bulb of the halogen bulb is filled with the usual mixture of nitrogen and argon, krypton, or xenon. In addition, the filling contains compounds of hall elements. Halogen bulbs have better parameters than ordinary bulbs. They are manufactured for mains voltage 230 V or as miniature and special types for low voltage (most often 12 V). They are more efficient than conventional light bulbs, but they are more expensive and have very low overvoltage resistance and short life.

They are easily dimmed, see this article.

Fluorescent lamps (low pressure lamps)

they are a popular source of light. With a fluorescent lamp, approximately 21% of the energy supplied is converted into light. The service life of fluorescent lamps is 8-12,000 hours.

Dimmable electronic ballasts controlled by a 0 (1) ÷ 10 V signal are used for dimming, see this article, or via the DALI interface - see this article.

Compact fluorescent lamps

(incorrectly "energy saving" or "energy saving lamps") are light sources that combine the properties of fluorescent lamps and the appearance of light bulbs. The compact fluorescent lamp belongs to the group of low-pressure mercury discharge sources and is designed as a fluorescent tube with an electronic ballast and base. Specific power ranges from 50 to 100 lm / W.

Only types that are specifically designed for this can be dimmed, see this article.

High pressure lamps (mercury, sodium, mixed, very high pressure, xenon lamps).

They are usually used for public lighting and similar purposes.

High pressure lamps usually do not dim.

A solution with DMX and DALI is available for dimming various sources, especially for more complex control. 

Basic concepts

Luminous flux (lm) – expresses the amount of light energy (total amount of radiation) that the light source emits, taking into account the sensitivity of the human eye (characterizes the light output of the light source)

Lighting intensity (lx) –  expresses the ratio of the incident luminous flux to the illuminated area.

The lighting intensity is 1 lx, when the luminous flux of 1 lm falls evenly on an area of 1m2.

Luminosity (cd) –  luminosity expresses in a certain direction (expressed by the spatial angle) the emitted luminous flux (a measure of the luminous flux radiated into a spatial angle).

Brightness (cd/m²) -  the brightness of a light source or illuminated area - is crucial for perceiving the brightness of light

Luminous efficacy (lm / W) – expresses how effectively the light source converts the supplied electrical energy into visible light (also the specific power of the light source).

Light color (color temperature, chromaticity temperature) – characterizes the color of light, given in Kelvin (K), expresses the temperature of an absolutely black body, whose light evokes the same color impression. This information is especially important for LED sources and fluorescent lamps

Color temperatures:

Color rendering index (Ra, more clearly CRI) - evaluation of the fidelity of the color perception, which is created by lighting from a particular source in comparison with what color perception would arise in sunlight. The CRI value can be 0 (colors cannot be recognized) to 100 (natural, perfect color rendering). For interiors with permanent residence of persons, a value of at least 80 is prescribed.

LED – basic information

An LED is usually (unless it is a combination of multiple LED colors) made of a chip that produces blue light through phosphors, which transforms part of this light so that the LED glows white as a result.

The resulting color rendering quality (CRI) is then usually inversely proportional to the efficiency. E.g. LEDs with a specific light output of 80 lm/W have a very good color rendering index (CRI) of 85%, with a CRI of, for example, 70%, the light output can be up to 130 lm/W.

Powerful LED chips (now commonly chips with a power input of W units) must be cooled. Part of the energy is converted into heat, which, unlike light bulbs, is not radiated and must be dissipated. Due to the fact that the recommended LED temperatures are up to approx. 80 ° C (surface temperature of the heatsink recommended approx. 55 ° C), it is necessary to mount the power LEDs on relatively massive heatsinks (which does not emotionally correspond to the highlighted excellent efficiency, but it is temperature and method of heat dissipation).

LED power supplies – selection and comparison:

Power – for ordinary interiors (replacement of fluorescent lamps, light bulbs) LED sources are already fully sufficient today and can solve problems in interior lighting with their luminous flux.

Efficiency – here, LEDs surpass almost all sources comparable in color rendering (higher efficiency is, for example, for metal halide lamps, which we do not use indoors).

Light color – here the LED also wins, it is possible to mix basically any color, which can be observed even when changing conditions (dimming, etc.)

Color rendering index – classic heat sources - light bulbs - win here. Today, however, LEDs already reach CRI 80 and more, so they can be used without problems for ordinary interior lighting, there are LEDs with CRI up to 90, which at the cost of lower efficiency and higher costs can replace light bulbs in special applications (gallery lighting, etc ..).

Lifespan – here LED also wins. The service life of LED sources is stated to be up to 50,000, sometimes up to 100,000 hours. Another advantage is any switching frequency and immediate start-up to full power).