Wireless Dimmers - Range?

Hi there,
I have the impression that the dimming range, particularly the lower end on the wireless product is somewhat restricted, i.e. the connected lights do not go down to 1%. It also seems to be related to the load.
I have not found anything in the specs which come with the product to get an idea what the range should be. Can anyone confirm what I see, or is there a spec out?

Regards
Thomas

 

Thomas

The minimum brightness setting is a tricky one. It's a requirement in some markets that at minimum brightness (not the off state) that the load is visibly turned On.

You are quite right when you say that the minimum brightness is related to the load. Different load types, such as incandescents, iron-core low voltage, electronic low voltage, fans etc, behave differently to the phase-control diming method. Electronic and iron core transformers for example both will give a different apparent brightness at the same conduction angle. As the firing angle advances the apparent differences become less obvious, as the eye does not respond in a linear fashion. It would be impossible to set a minimum brightness that gave the same result across all load types.

Another effect is that it's important to not dim the load completely Off, as the load indicator would still be On and any monitoring software would indicate that the load is in the On state.

More than anything, it's just a matter of making sure that we are covered for all the markets in the world where the product is sold and that no unpredictable behaviour is observed.

 

Thanks for your reply Newman,

Your answer is clear an naturally correct. My query is related to the fact that the minimum brightness that I find with the wireless product is quite high, I would guess 10% on an incandescent, while I'll give it 3% on an electronic transformer with 150 Watt load. By the by, I am using the trailing edge version of dimmers.
This relatively high minimum eliminates the problem of dimming so low that the load is on, while the dimmer isn't "off". But it leaves the light too bright. This is not always an issue, but for some locations and applications, this is similar to the poor dimming range of some electronic control gear for fluorescents.
Further, we achieve a much better range with the wired product, where we get an almost smooth transition from zero to 100%. I am sure the same legalities would apply there?
Another question which you might clarify is how the load, lets say, 25W versus 200W on a 1-channel dimmer would influence the minimum range, if at all?

Regards
Thomas

 

The biggest difference between the C-Bus wired and wireless devices is that the Wireless products only have a 2-wire connection. This brings it's own set of constraints upon what can be done. You don't get something for nothing, as they say! The wired C-Bus product is a 3-wire design and there are more options from a design perspective.

The larger the load the lower the minimum brightness setting will appear. This is because of the thermal intertia of the larger lamps. A firing angle that has a 500W lamp apparently Off may leave a 25W lamp with a noticeable glow.

The more heavily loaded the channel is then the lower the minimum setting will appear to be. This is because the Off-state power consumption of the device is spread across more loads and the lamp heating due to this is reduced. The less power per half cycle flowing through the lamp, the dimmer it will be. How great a visual difference there would be between a 25W and a 200W load, I'm not exactly sure.

To give you some idea of what actually is happening at the load, the power being delivered to the load at minimum brightness is approximately 2% of the total power in a mains half-cycle.

 

O.k. that is valuable info, and makes sense . The reason why I ask is that the wireless product is obviously a retro-fit product, and as far as I am concerned, will be in most cases tied in with a wired network.
That being said, there will be the percieved and real difference in certain aspects of product performance, but as we are talking about a retro product, we also need to compare ourselves only to the crappy wall mount dimmers commonly available. In that regard, the wireless product still is fine. I say fine, because there are some things which are not ideal, or up to scratch.
I also would like to mention that it appears that the comms between the wireless products are not 100%. As it is a wireless product, I think that that is the way things pan out, but... Assuming that this is caused by marginal comms due to distance or interference, it may be good to include a signal strength- check- routine. I am thinking here of the type available with Bluetooth products, even some wireless security products. It may be that this is not a priority for you now, but as retrofit products are most likely to find their way into private residences and consequently in the type of setup I mentioned above with scenes and schedules run off a Touch Screen, reliable comms are an advantage, to put it that way.
Anyway, that's my couple of cents worth of opinion.

Thank you for your replies, Newman
Regards
Thomas