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Using LEDs in homes, especially smart homes, is now common-place as they use as little as 10% of the energy of a conventional incandescent or halogen bulb. But they do behave differently to conventional bulbs and in many cases you need to take consideration when using them with Fibaro Dimmer 2 modules.
This application note shows how to use a Fibaro Dimmer 2 module with LED lighting in a Home Automation installation.
LED bulbs are very different to the conventional bulbs they're replacing. Conventional bulbs are based on a simple 'filament' wire that glows white hot as the electrical current passes through it. If you vary the voltage and current applied to the bulb you can directly change its brightness.
LED bulbs are more complex, they include electronic circuitry to control them and enable them to work in domestic mains (230V) electrical systems. It's this complexity that allows them to achieve such great power saving efficiency but also what makes them more difficult to use with dimmers of any type.
Many dimmers cannot be used to control LEDs (even if the LEDs are dimmable), so you need to choose a 'Universal Dimmer' such as the Fibaro Dimmer 2 module that is designed to work with a variety of lighting sources including LEDs. It intelligently analyses the bulbs connected to it and then selects the most suitable dimming type - trailing-edge or leading-edge.
Electronic loads like dimmable LEDs may be designed to work with trailing-edge or leading-edge dimmers and the Fibaro Dimmer 2 is designed to take this into account, configuring itself to the best mode to work with your LEDs.
Even though the Fibaro Dimmer 2 is designed to work with LEDs, there are three important points to observe; the dimmer's minimum load, its maximum load and its configuration to work with LEDs.
The Fibaro Dimmer 2 has different minimum and maximum load ratings depending on the type of load you are using it with and whether you are using the Fibaro Dimmer Bypass 2.
The Fibaro Dimmer Bypass 2 acts as an intelligent load in the lighting circuit and will help prevent the LEDs flickering at startup, low dim settings or when they should be Off.
The Fibaro Dimmer Bypass 2 should be installed in one of the light fittings or in the wiring going to the light fitting (Figure 1), it must be connected between the Switched Live coming from the Fibaro Dimmer 2 going to the light fitting(s) and the Neutral. You only need one Fibaro Dimmer Bypass 2 for each circuit (not for each light bulb).
Note: You must use the new Fibaro Dimmer Bypass 2, do not use the older Fibaro Dimmer Bypass as this may damage the module or your LEDs.
Figure 1: Installing the Fibaro Dimmer 2 and Bypass 2
LEDs can generate extremely high in-rush currents when they initially start up, especially if they are being controlled by a leading-edge dimmer. This means that it is easy to exceed the maximum load on the Fibaro Dimmer 2 without even realising it!
It is therefore common practise to de-rate the maximum power rating of the Fibaro Dimmer 2 when using LEDs. According to the technical specifications of the Fibaro Dimmer 2 it is rated for between 50-200VA when used with LEDs without the Fibaro Dimmer Bypass 2 and 5-200VA when used with LEDs with the Fibaro Dimmer Bypass 2.
To get an exact power rating in Watts you need to know the "Power Factor" of your LEDs and use the following calculation:
W = VA x PF
So for example, if your LEDs have a Power Factor of 0.5 then your calculation becomes:
W = 200VA x 0.5PF
So you can see that the Fibaro Dimmer 2 should be de-rated to 100W when used with your LEDs.
You can also apply the rule to find the minimum load:
W = 50VA x 0.5PF
W = 5VA x 0.5PF
Here you can see that the minimum load when using the Fibaro Dimmer 2 with your LEDs should be 25W when not using the Fibaro Dimmer Bypass 2 and 2.5W when using the Fibaro Dimmer Bypass 2.
That said, this isn't a hard and fast rule so we would always recommend experimenting with your LEDs with and without the Fibaro Dimmer Bypass 2 and hopefully you will get satisfactory results!
Note: When installing or removing the Fibaro Dimmer Bypass 2, or making any changes to the load (for example bulb type or rating) you must re-calibrate the Fibaro Dimmer 2 after each change!
The Fibaro Dimmer 2 has an auto-calibration feature that detects the type and rating of the bulb(s) being used. During the calibration cycle it configures the dimming type between leading-edge and trailing-edge and adjusts various settings such as dimming level and rate to suit the load.
In most cases you should not need to make any further changes to these settings and in fact we recommend that you leave them well alone unless you fully understand what each setting does!
By default a calibration will be performed after the first power on. For that reason it is not advisable to power on the Fibaro Dimmer 2 without the desired Load.
During this period Z-Wave connection is disabled and the Fibaro Dimmer 2 will not reply to any commands.
The calibration result will be confirmed with the LED indicator glowing in one of the following colours:
By default the calibration is performed without the Fibaro Dimmer Bypass 2. If you have a Fibaro Dimmer Bypass 2 installed it is required to force the appropriate calibration procedure using the B-button menu or Parameter 13.
When installing or removing the Fibaro Dimmer Bypass 2, or making any changes to the load (for example bulb type or rating) you must re-calibrate the Fibaro Dimmer 2 after each change!
The lighting should not be used before changing the operating mode or calibration procedure.
Installing the Fibaro Dimmer 2 modules involve working with 240V mains wiring. If you are not comfortable doing this you should consult a qualified electrician. This application note is provided as a guide, all work is are carried out at your own risk. Vesternet do not accept any responsibility or liability.