NEMA White Paper On Dimming LED 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

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.

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

Craig Blackley

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.

Craig Blackley

Thanks for the info Craig!  I have been doing my own testing with a number of lamps and have been struggling to find something that works well-STILL (as I see you were evaluating over a year ago.)

My findings...

The lamp that seems most viable right now is the TCP PRO LED17E26P3830KFL 3000K 17W dimmable 40 degree 1050 lumen lamp

I have also tested but was less impressed with either the light output, color temperature, or operation of the following:

Sylvania- Ultra LED18PAR38/DIM830/NFL25/HVP 18W dimmable Par 38 900 lumen-poor dimming on the low end, flicker and off
FEIT Electric PAR38/WP/LED 21W dimmable Par 38 1200 lumen-poor dimming, snap off
Phillips BC19.5PAR38/AMB3000K FL25 DIM 120v Par 38 1200 lumen-flicker and snap off
GE Energy Smart Technology LED20DP38S830/40 Par 38 1100 lumen-flicker on the low end
Green Creative Titanium LED Series 2.0 01-706-D/830-25D Par 38 1160 lumens-poor color temperature

Toshiba 20P38/30LFL-UP dimmable Par 38 1120 lumen-good color temperature but flickering as it dims

Lighting Science Definity LBL-00225 dimmable Par 38-good color temperature and very little flicker but it does snap out at the end.

The color temperature and when the LED fades out are significant because my houselight system of 300+ par lamps also works with about 30 Par 56 lamps that I would need to convert to medium screw base units which I don't have the time for at the moment.

Best!