Part 1: dimming LED lighting solutions
November 16, 2018
Illuxtron International has many years of experience in developing various LED lighting solutions. The dimming methods are very important in this. Illuxtron LED fixtures can be dimmed in many ways. But how does dimming actually work and what do you have to keep an eye on? In this series we explain the different options.
Dimming means reducing the current supplied to the fixture. This reduces the lumen output and the light intensity decreases. It is possible that the dimmer will not work properly with the fitting. That can be seen in various ways:
• The fitting flickers when it is dimmed or switched off.
• There are also cases where it cannot be dimmed right down to a very low light level.
• And cases where the maximum light level (100%) of the fixture cannot be achieved.
Illuxtron has tested the most widely used dimmers. The result is a list of dimmers that can be found at the back of our catalogue. If a dimmer is not on this list, we cannot guarantee that there will be no problems with dimming. If a dimmer is on the list, it will generally work fine.
Dimming low voltage lumiaires
If a dimmer is to work properly with a low-voltage system (with a driver), a dimmable driver (AC dimmable) should be used. These drivers can be found on our website under Downloads, TCI driver list. The benefit of this situation is that you can reuse the existing dimmer when renovating.
Note: There are also drivers that are directly dimmable without a separate dimmer needing to be included. This generally gives a better dimming a result. They are usually operated by a pulse signal or a digital signal. This therefore means extra wiring from the operating point to the driver, although this is increasingly being superseded by new techniques such as wireless operation.
Casambi  is an example of this.
The dimming process
The 230V mains supplies a voltage that varies as shown in Fig. 1a. When you connect that to a fixture, you get the maximum amount of light output. The light source is fully on.
When you start dimming, the dimmer takes a ‘bite’ out of the sine wave so that there is less current available for the fixture. The light output is therefore less. The size of the ‘bite’ is adjustable from being a very small nibble (the fixture is then fully on) to a very large bite (the fixture then only emits a small amount of light).
That ‘bite’ can in principle be taken in three ways:
• Leading edge: a bite is taken out of the start of every sine wave.
• Trailing edge: a bite is taken out of the end of every sine wave.
• PWM dimming (pulse width modulation – Fig. 2): is a bit more complicated and expensive, but it does have a number of advantages Within a single sine wave, small pieces of the current are allowed through to the fixture a large number of times. The dimming percentage is 50% in Fig. 2, comparable to Fig. 1b and Fig 1c, but it has been achieved in a different way.
Dimming methods leading and trailing edge are also referred to as triac dimming.
Pros and cons of the dimming methods:
Controlling (operating) the dimmer:
The dimming process can be controlled (operated) in a variety of ways. Each of these methods involves ‘telling’ the dimmer what it has to do.
• Using a knob
Turning the knob anticlockwise reduces the light output and clockwise gives more light.
• Using one or two pushbuttons (a ‘push’ dimmer or a ‘pulse’ dimmer)
You use these to give an ‘up’ or ‘down’ instruction.
• Using an analogue control voltage that varies from 1 to 10V.
A voltage of 1V results in a minimum light level; voltage 10V gives the maximum light level.
This control voltage is supplied by an external system such as a domotics system or a computer.
• Using a digital signal
Various so-called protocols are used for this:
Combinations of the systems mentioned above also occur, for example: operating a 1 – 10V or DALI system using pushbuttons.
Casambi is a technique for controlling lighting simply that is very much on the rise. Illuxtron fittings are compatible with this system as long as the correct dimmer or switch is used. The smart digital dimming system is operated using an app on a phone or tablet.
If you would like to connect Illuxtron fixtures to a Casambi app, that’s fine. Smart dimmers are available for every type of lighting. See www.casambi.com for more information. Ask our Sales team about the options for supplying Casambi via firstname.lastname@example.org.