Conventional Fixtures LED House Lighting

[yanksrule0422]

Hi,

Recently my church maintenance team decide to go forth with an LED house lighting project. Unfortunately they didn't consult me and now we have issues.

They converted all house bulbs to LED. Our 60 watt incandescents were replaced with their LED counterparts (i dont have a specific model). They replaced our reflector incandescents (i'm not sure the exact model) with TCP LED12DR5627K LEDs.

The issue is that the dimming curve on these lights is not appropriate for a church. They stay rather bright until they reach about 35%. Only then does the dim become much more noticeable. Simultaneously, they flicker below 20%. The closer it gets to 0, the worse the flicker is. And lastly, when they reach 3% they cut off.

The church definitely wants to stick with LED, what would be the most appropriate course of action in fixing this issue?

 

[sk8rsdad]

In general, LEDs don't dim well on systems designed for incandescent loads. There are exceptions, but it would seem your combination of dimming and LEDs is not one of them.

It may be possible to get better results by replacing your dimmers with reverse phase ELV and finding a more suitable dimming curve. They're still likely to drop out below a certain voltage and pop on though. Hunt up the manufacturer's recommended dimming and see what it will cost to retrofit your facility.

http://www.tcpi.com/spec-sheets/DOCUMENTS/LED Downlights Spec Sheet.pdf

 

[TheaterEd]

Talk to your dimmer Manufacturer. It took a lot of work to get my dimmers playing nicely with our LED house lights. Odds are though you will never get a smooth curve all the way to zero. Good luck.

 

[ElGusto]

Out of morbid curiosity, what kind of LED lamps did they get?

 

[yanksrule0422]

In general, LEDs don't dim well on systems designed for incandescent loads. There are exceptions, but it would seem your combination of dimming and LEDs is not one of them.

It may be possible to get better results by replacing your dimmers with reverse phase ELV and finding a more suitable dimming curve. They're still likely to drop out below a certain voltage and pop on though. Hunt up the manufacturer's recommended dimming and see what it will cost to retrofit your facility.

Thank you for the reply!! A couple questions:
What is a reverse phase ELV? Also which manufacture would recommend the dimming (dimmer packs or LEDs)?

Also idk if it's worth mentioning, but we've currently got NSI DDS 9800s as our dimmer packs and a GrandMA1 as our main console

 

[BillConnerFASTC]

What kind of dimmers?

In general, mains dimming of LED retrofits will never be real satisfactory. We have had limited success with a few combinations and generally for sconces or in places where low end cut off is not an issue.

The TCP lamps - some of them - are among the best of retrofits for mains dimming, but still has to be a high quality dimmer. Don't forget reduced load means you can usually reduce total number if dimmers.

How the quality of light otherwise? At all warm? Do people look good under it?

 

[yanksrule0422]

What kind of dimmers?

In general, mains dimming of LED retrofits will never be real satisfactory. We have had limited success with a few combinations and generally for sconces or in places where low end cut off is not an issue.

The TCP lamps - some of them - are among the best of retrofits for mains dimming, but still has to be a high quality dimmer. Don't forget reduced load means you can usually reduce total number if dimmers.

How the quality of light otherwise? At all warm? Do people look good under it?

NSI DDS 9800s

The color temp isn't bad whatsoever

 

[BillConnerFASTC]

I'm not sure but I doubt those dimmers will ever do a good job mains dimming LEDs, nor is there likely to be a retrofit module. I'd add up LED loads and then look for a dimmer and do a little rewiring in the dimmer room. I like the Fleenor DMX8DIM. Does a great job with the TCP designer series lamps.

 

[yanksrule0422]

I'm not sure but I doubt those dimmers will ever do a good job mains dimming LEDs, nor is there likely to be a retrofit module. I'd add up LED loads and then look for a dimmer and do a little rewiring in the dimmer room. I like the Fleenor DMX8DIM. Does a great job with the TCP designer series lamps.

For the sake of learning, what is a retrofit module?

What do you mean by adding up the LED loads? Is that literally finding out how much power they take up together?
What would be an adequate substitution if my dimmers turn out to need more than 250 W?

 

[Les]

For the sake of learning, what is a retrofit module?

What do you mean by adding up the LED loads? Is that literally finding out how much power they take up together?
What would be an adequate substitution if my dimmers turn out to need more than 250 W?

A retrofit module is more of a term for freestanding dimmer racks, where the actual dimmers can be slid out (usually in pairs). A retrofit module would mean keeping the existing infrastructure of the dimmer rack itself and only replacing either the dimmer modules on or the control module. I can't say for certain but it seems that the dimmer unit you have is a rackmount, meaning it is self-contained and not user-serviceable.

Hopefully I haven't confused you more.

Yes, I believe he meant finding the sum of all the LED fixtures added together to see how much power they are actually consuming and redistributing as necessary.

What do you mean by needing more than 250w?

 

[yanksrule0422]

A retrofit module is more of a term for freestanding dimmer racks, where the actual dimmers can be slid out (usually in pairs). A retrofit module would mean keeping the existing infrastructure of the dimmer rack itself and only replacing either the dimmer modules on or the control module. I can't say for certain but it seems that the dimmer unit you have is a rackmount, meaning it is self-contained and not user-serviceable.

Hopefully I haven't confused you more.

Yes, I believe he meant finding the sum of all the LED fixtures added together to see how much power they are actually consuming and redistributing as necessary.

What do you mean by needing more than 250w?

Thank you for the reply! You actually cleared things up quite well. Our dimmer packs are in fact rackmounts, which in turn does mean self-contain and not user-serviceable.

Let's say I have 40 LED fixtures that each needs 10 W. They're all on the same circuit giving me a grand total of 400W. I glanced at the specs for the DMX8DIM and it says that each output is rated for 250 W. Essentially, if I'm correct in my logic, I need 400 W but only get 250 W/channel. That's where I'm confused and wonder what would I do next.

 

[Les]

Ah, I see. In the event that you have over 250w total, you'd have to split the circuits and put them on a separate output. It really wouldn't hurt to divide them evenly between 4 outputs or so - it's helpful at times to have the ability to control groups of house lights separately. Of course, this would potentially require some re-wiring.

 

[yanksrule0422]

Ok I have a couple more questions then:

Lets say I can't rewire and split circuits. Is there a step up from the DMX8DIM, that handled more power?

Also for general knowledge's sake, why do LEDs behave like this? Each output on my dimmer pack is rated for 2000W. Let's say i plug in an S4 that only needs 575W, or a string of Incandescents that need a total of 300W. Why dont those stay bright until the dimmer is at ~25% where it then can output the correct amount based off of its max power?

 

[TheaterEd]

I would also urge you to split them onto separate circuits. Mine were originally all on two circuits, but they started playing nicer when we split them onto 4.

 

[BillConnerFASTC]

LEDs require a power supply or driver. The driver requires power to output regulated power to the LED array. When the voltage drops below what's needed to run the driver, it stops outputting power to the LEDs. That's a very simple description but the issue. Its why LED fixtures require constant power and data to control the driver.

Incandescent sources are just an electric heater and output is proportional - not linear but directly related - to the power supplied.

Digital vs analog in a way.

I'm sure the original incandescents were divided onto far more circuits than needed for the LEDs so no dividing, just combining. Do a schedule showing how many LEDs on each circuit and how many circuits and it should be easy to figure out the right dimmer additions or modifications.

 

[Calc]

Have you tried adding a ghost load to the system? It might help with the flickering a bit. Everything will still cut out at the same place, though.

 

[yanksrule0422]

Have you tried adding a ghost load to the system? It might help with the flickering a bit. Everything will still cut out at the same place, though.

What's a ghost load??

 

[GreyWyvern]

Here is the wiki entry for ghost load. Basically, it is added resistance on the line to trick the dimmer into thinking it has a full load.

 

[robartsd]

What's a ghost load??

Quite often a small incandescent lamp is used (60-100W).

 

[Senorfish]

Here's a compatability document which explains the different LED dimming technologies, and brands of lights that are "supposed" to work with them.
http://www.liton.com/webcatalog/brochures/wp_dimmingfacts.pdf

The problem I have with LED house lights (besides dimming) is that the light is very directional and casts hard shadows. Maybe that's ok in a church where you only need to read what's in front of you. We have LED work lights and it is so hard to work on stage in the shadow 'narrow' coverage of light. Really want to replace them with some good old flourescent tubes.