IGBT/Sinewave dimming?

T

TJ Cornish

Graduate
Jan 13, 2011
1,263
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St. Paul, MN
We're looking at doing some architectural lighting upgrades replacing a VERY old rotary relay system in my church. I'm aware of the desirability of non-SCR dimming for LED bulbs which are likely at some point in the future.

According to this paper from Strand/Philips http://www.strandlighting.com/clientuploads/directory/downloads/Strand_IGBTvsSinewave_Dimming.pdf IGBT dimming is the best of all worlds.

According to some other reading I've done - TheSilence of the Lamps: The New Wave in Dimming and some other docs, it seems like that may be a little generous, and true sinewave dimming would be the most future proof.


So far I'm familiar with Strand A21, the lightolier Bak Paks and bars http://www.lightolier.com/MKABrochures/Comprehensive/files/assets/downloads/page1240.pdf, the ETC Sensor+, and a couple oddballs that show up in Google. The most desirable form factor for us is probably the BakPaks - little pods that can be stuck near the load, which save us from having to re-work the current distribution to make room for a panel like the A21, however I would really like 2K capacity - the largest BakPak is 1.2K.

Anything I'm missing? It's a church so cost is of course a factor, but I don't want to buy twice since it seems that LED fixtures and/or replacement bulbs aren't too far off.
 
Re: IGBT/Sinewave dimming?

A modern sinewave dimmer is simply an AC to AC SMPS. They are not entirely load-independent, and some of them can behave strangely when presented with loads that are significantly capacitive or inductive. I'm not convinced that they have any significant advantages for applications that can tolerate a chopped-waveform (most LED retrofit lamps can tolerate a chopped waveform from at least some dimmers).

The big advantage to the IGBT-based dimmers is the controlled turn-on and turn-off behavior. This allows for the elimination of the output filter (big inductor) and the ability to chop either the beginning or the end of the waveform. So you can build a lightweight dimmer that can handle either inductive or capacitive loads, with almost any rise time you want.

Right now, only Philips (previously Genlyte and Entertainment Technology) makes IGBT-based entertainment dimming for sale in the US. This is due to the ownership of the patents on the technology. Any dimming larger than a simple wallbox dimmer sold by Philips in the US is a Strand product - those Lightolier BakPaks are Strand LightPacks. If you need 2.4K dimming, want IGBT, and don't want a panel design, look at the Strand S21 strips. Very similar dimmer modules to the A21 in a pipe-mount version, and also have options for relay and LED fixture modules.

Note: I work for Philips (but not Strand).
 
Re: IGBT/Sinewave dimming?

Thanks for the info Rob. I didn't realize there were patent issues preventing more firms from using IGBT tech. The S21 strips are interesting, and I have a quote on them from our dealer, but the form factor isn't ideal, since this is architectural lighting, which is hardwired, and the strips still require heavy power input. The advantage of the RakPaks is we can simply remove the relay, and hardwire in the RakPak dimmer inline. Unfortunately 1.2K is a little tight for some things.

I'm very familiar with Philips EnduraLED bulbs. I've got about 200 hours in a lighting retrofit at my company and this is what we're using. Dimmer compatibility is marginal - even with at least one type of "LED-safe" dimmer. We're still working on that part. Other than that (and the price), we really like the bulbs. The light quality and pattern is great, and we're actually replacing more than one old Par30 bulb with a single 36 degree EnduraLED, so energy savings is more like 100 watts -> 12 watts. It's been an interesting project.
 
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