Got this from ESTA Standards watch & thought others might find it useful:
On February 23 the National Electrical Manufacturers Association published LSD 49-2010, Solid State Lighting for Incandescent Replacement—Best Practices for Dimming, which can be downloaded for free from the NEMA website at http://www.nema.org/stds/lsd49.cfm. The white paper discusses some of the technical issues and provides recommendations for the dimming and design of screw-based incandescent replacement LED lighting products.
The white paper probably doesn't contain anything that would be news to engineers and technicians involved in the design of commercial LED luminaires for the entertainment market. However, it might be a good, succinct introduction to some of the technical issues with LED drivers and dimming for those who don't have to design the equipment but who have to explain it to customers, and for people who are beginning to dabble in LED lighting for the home. Chapter 4 on LED drivers gives a description of the voltage/current characteristics of LEDs and is a good education for those who think that LEDs can be strung together like incandescent lamps.
Jeff,
I have to agree that it has some good basic info and everyone should read it. It's really not that long or too terribly technical [says the guy with the EE].
I will say that it ultimately disappointed me as the doc was suposed to be "Best Practices for Dimming" and the closest it came to that was:
"To summarize: the incandescent lamp dimmer reliability is ensured if each of the stresses when the dimmer drives non-incandescent loads is less than the stress when the dimmer drives the rated incandescent load. "
Since we are getting lots of calls from people wanting to know if Brand X LEDs will work on ETC gear, I was hoping this doc would help set some standards. Guess not.
Oh well, read, enjoy, ask questions, and have fun.
David
I have an installation where we have put in 2 EnR racks, with D20 modules- they are running in test mode while the rest of the building gets completed.
I was onsite today and noticed that the electrician was puting in LED Par lamps inthe houselight fixtures- this was a change from the planned incandescent lamps.
Some of the lamps are flicking on and off- but it is single lamps on a shared circuit, not all the lamps. This may have nothing to do with the dimmers, but the flickering is quite regular.
The panic reaction was that the lamps and dimmers were not getting along with each other.
The data sheet for the lamps ( Philips EnduraLED ) says they will dim to 10% and are designed for " leading edge Triac dimmers"
Since the dimmers are in test mode, I assume they are geting a pretty dang clean waveform.
I haven't connected DMX to the racks yet, but I will do that next week, and see what happens when they actually dim.
Anybody have any thoughts or experience with this ?
I'm a bit nervous about potentially dmamging my dimmers, or a large quantity of expensive LED lamps.
I'm more nervous about having to tell the engineers that they will have to change to a different dimmer module
Craig Blackley
Craig Blackley, Jack A. Frost Ltd.
Philips actually sent us a few of the Endura style lamps to test with our dimmers recently. We did find behavior similar to what you're seeing under certain circumstances. It most frequently happened when the lamps were turned off briefly, then back on. After that, a few lamps on a given circuit would sometimes start blinking at a regular rate. Oddly enough, this is actually more likely to happen at full than when set to any level less than full. It also happens less often when fading to full instead of snapping on.
As you saw in the datasheet, the product is meant to be dimmable and it is designed for the type of dimmers you're using. It does have a reasonable range of dimming, and (aside from the blinking) can be set to any level without flickering. They did appear somewhat steppy while fading from one level to another, though.
While undesirable, the blinking behavior is not something that should cause any damage to the dimming system. You'd have to check with Philips to see if they're concerned about damage to their product. The (slightly) good news is that this is something they should be aware of now, so they may be working on a solution. The not-so-good news is that this isn't a problem that can be fixed by choosing a different dimmer module.
Mark Penisten--ETC Associate Systems Engineer
Hey thanks for the great info.
I like to be the kind of supplier "who makes it work" but in this case, I'm glad to know its not really my problem.
The fading shouldn't be too much of a problem- these are houselights in a hospital auditorium- I thin kbeing able to set them to a dimmed level is more important than the actual fade
Hopefully the problem will be witha few lamps, that they can swap out.
I'lll post a follow up note once we get DMX control on the system, and we do complete testing
As promised- a follow up on our installation of Philips LED lamps
When the Unison rack is running "with processor" ( as opposed to in test mode ) the lamps are much happier
Some of them still go into their flashing mode- if yuo snap their power on.
When changing levels with even a short fade ( 1 second) they do not start flashing.
So our system runs with presets from Paradigm, and from an ELement- so the lamos are all happy.
Fading is pretty good- down to about 20%. The odd behavoir is that at the low end all the lamps on the same circuit do not fade together. Its not too noticable if the fade is not too slow- at typical "house light " speeds it is quite accaptable.