Flickering Lights

[Chaos is Born]

Has this happened since the system was installed?
I only know of the last 4 months for sure... And from the sound of it at least the past year.

Were there any recent changes to the building that might affect the data line coming into the rack?

None that i can think of... building is only two years old so i don't think so.

It sounds like there might be some interference in the data line somewhere along its path. Are you able to trace the conduit down all the way from the booth to the racks?

Haven't tried, i would have to look at the Electricians blue-prints since its all routed into the walls.

Is this rack being driven by DMX? or Network?

Network.

Edit: After tracing the lines all lines are seperate from anything that would cause interferance... Completly seperate conduit from anything else in the building.

 

[NeroCaesar]

Hello I have a similar problem.

I have an Ion light board
1 96 ch EDI mx rack
and 30 D4 leviton dimmer packs

recently I hardwired some modules to be non-dims to power a few (8x) D4s and it worked fine
So I went out and bought more D4 backs to expand my control of my lights

so now I have one dmx going to the EDI rack which controls 28 lights
and another dmx that is going out to the daisy chain of D4 packs ending in a terminator (all being powered by EDI non dim modules)

now when I turn up a large number of units at 30%ish the units on the dimmer packs start to erratically flicker

The EDI has a voltage meter on the front and it fluctuates from 125volts to 119v.

My first hope is that if I split the 30 d4 box chain with an iso that will help

My second thought is that when I modified the modules I bypassed the choke so I am going to try to undo that

My 3rd thought and fear is that I will need to find another way to power a lot of these D4 boxes.

Any thoughts? Was I crazy to try this in the first place? ... it worked on a smaller scale...

some one mentioned something about common neutrals might have something to do with it but Ive done a lot of things like this for industrial without it being a problem (sans going through an edi rack).


Thanks in advance,

 

[derekleffew]

... now when I turn up a large number of units at 30%ish the units on the dimmer packs start to erratically flicker ...

Perhaps this? From http://www.controlbooth.com/forums/...ing-when-dimming-house-lights.html#post264354 :

... This is much more likely to be jitter caused by a simple-minded or marginally-designed zero-crossing detector ( Dimmer, zero crossing referenced ) in the dimmer, especially if the AC line is noisy. ...

-----

... recently I hardwired some modules to be non-dims to power a few (8x) D4s and it worked fine ...
My second thought is that when I modified the modules I bypassed the choke so I am going to try to undo that ...
Any thoughts? Was I crazy to try this in the first place? ... it worked on a smaller scale ...

For safety and legal reasons, ControlBooth DOES NOT recommend, advocate, approve, or condone altering one's dimmer modules.

...
I'm not trying to call you out directly, but I take great issue with what you are suggesting here. As an ETCP Certified Entertainment Electrician, and a factory authorized field service technician for various manufacturers, I want to emphatically state that an end user should *NEVER* modify a dimmer rack in this manner. The liability and risk of injury or death is too great.

Modifying the dimmer rack can void the dimmer rack warranty, voids UL (or ETL, or whomever), and likely makes you, your venue, and your employers/supervisors responsible for any and all damage this may cause if something fails. You risk, at the least, damage to the dimmer rack and connected devices, and at most, loss of life.

I implore you, if you need power that can't come from a dimmer...install a relay module if you're able to / your rack has that option, or have a licensed electrician help you come up with a safe and viable solution. ...

You have a much bigger issue here. If the rack is permanently installed, the electrical system feeding it underwent a fault current analysis based on the original Short Circuit Current Rating (SCCR) of the rack. By modifying the rack or bypassing chokes (which are one of the primary contributors to the SCCR), you could create an unsafe condition. You need to determine what the SCCR of the rack is when a "breaker only" module is installed (get this from the manufacturer), and verify that that SCCR rating coordinates with the available fault current on your feeder. This must be done by a licensed electrical engineer.

Plus, what Abby said in the post Derek pointed out. Do not modify it yourself.

ST

( Sorry that we didn't raise this issue more emphatically back in May. )

-----

But I suspect, if it matters at all, it would be better with the choke removed from the circuit. See http://www.controlbooth.com/forums/lighting-electrics/21726-cd80sv-power-module-retrofit.html .

.

 

[JChenault]

Perhaps this? From http://www.controlbooth.com/forums/...ing-when-dimming-house-lights.html#post264354 :

-----

For safety reasons, ControlBooth cannot recommend or condone altering one's dimmer modules. But I suspect, if it matters at all, it would be better with the choke removed from the circuit.

.

Derek
I understand that this is a purely hypothetical discussion, but why do you think that removing the choke would make things 'smoother'. My intuitive understanding of the choke is that it's job is to effectively smooth out the choppy waveform just a bit. While the amount of smoothing should not make a visible change, if it did - seems like the choke would make things smoother, not more choppy.

My electronic understanding is not completely solid on this opinion - could someone who understands it deeply comment?

 

[derekleffew]

...but why do you think that removing the choke would make things 'smoother'. ...

I don't believe I ever said anything of the sort:

But I suspect, if it matters at all, it would be better with the choke removed from the circuit.

I was trying to save the OP the step of trying it with the choke back inline.
My suspicion comes from observing the Sensor R20 and CC20 non-dimmer modules. If a choke was required/warranted/beneficial, they'd have one (two, actually). But they don't. So it must not be.

Also this, from Sensor3_SR3_ThruPower_Module_Spec_Sht_vB.pdf :

In bypass mode, the integral relay will eliminate the choke and SSR power cube thereby providing clean power to critical power supplies and lighting devices.

Bolding mine.

However, JD, STEVETERRY, and DavidNorth's comments about chokes contributing to a rack's SCCR rating and that this must be coordinated by an electrical engineer raises another question in my young impressionable and inquiring mind: How then does one ever plan a system with move-around-able R20/CC20/ThruPower modules? Substituting an R20 or CC20 is often suggested as a solution, with no mention or seeming concern for SCCR issues.

.

 

[DavidNorth]

Also this, from Sensor3_SR3_ThruPower_Module_Spec_Sht_vB.pdf :
Bolding mine.

However, JD, STEVETERRY, and DavidNorth's comments about chokes contributing to a rack's SCCR rating and that this must be coordinated by an electrical engineer raises another question in my young impressionable and inquiring mind: How then does one ever plan a system with move-around-able R20/CC20/ThruPower modules? Substituting an R20 or CC20 is often suggested as a solution, with no mention or seeming concern for SCCR issues.

.

It's quite simple. All of those modules have current limiting fuses in them to maintain the proper and required SCCR rating. The same is also true of the D20FB module.

David

 

[DavidNorth]

now when I turn up a large number of units at 30%ish the units on the dimmer packs start to erratically flicker

The EDI has a voltage meter on the front and it fluctuates from 125volts to 119v.

My first hope is that if I split the 30 d4 box chain with an iso that will help

My second thought is that when I modified the modules I bypassed the choke so I am going to try to undo that

My 3rd thought and fear is that I will need to find another way to power a lot of these D4 boxes.

Any thoughts? Was I crazy to try this in the first place? ... it worked on a smaller scale...

some one mentioned something about common neutrals might have something to do with it but Ive done a lot of things like this for industrial without it being a problem (sans going through an edi rack).


Thanks in advance,

Based on your description, notably that turning on large numbers of lights in the EDI rack at about 30% coincides with a flicker on the D4s, says pretty definitively to me that the D4s are not able to deal with the power line noise on the feed. Worst-case harmonics are setup on the feed when phase-controlled dimmers are run at about the 33% level. Don't forget that curves on dimmers may mean the real number on the console is something other than 33%.

High current draws on the feed at that level can cause enough disturbance at voltage zero-crossing that a lesser designed dimmer cannot compensate and fire at the right time. Phase-controlled dimmers use the voltage zero-cross to then calculate when to fire the power device; triacs in this case.

If you fire fewer dimmers on the EDI rack and/or do not see the flicker at most any other control level, then indeed the two issues are connected. Provide a different power source for some of the D4s and see if they then act correctly. If so, there are a couple of options.

- I did see that you bypassed the chokes and am assuming that you are still powering the D4s off the SCRs. Since most dimmer racks regulate, it is possible that the dimmer rack is causing the SCRs in the module to change level which then causes the D4s to see the wrong waveform and then misfire. I highly recommend for that reason, and many more, that you undo your mods and find a different method of powering the D4s.
- Hire an electrician to come in and verify that all your neutral feeds to the EDI rack are secure and torqued [thermal cycling over time may loosen these]. Have them check all the feeds while they are there.
- Use something other then D4s.

Let us know what you find.

David

 

[derekleffew]

... If you fire fewer dimmers on the EDI rack and/or do not see the flicker at most any other control level, then indeed the two issues are connected. Provide a different power source for some of the D4s and see if they then act correctly. If so, there are a couple of options. ...

Hypothetically of course, What if the OP used only D4s, and no dimmers on the EDI rack? Would the harmonics created by one shoebox dimmer wreak havoc with others on the same service?
-----

... - Use something other than D4s.

Other than the brand new ES750, does ETC offer a product comparable to (but better than) the D4DMX? The SM4-10-A, 4 circuit SmartModule 2, 1x20A Cable In, Dual Edison Out, perhaps?

 

[DavidNorth]

Hypothetically of course, What if the OP used only D4s, and no dimmers on the EDI rack? Would the harmonics created by one shoebox dimmer wreak havoc with others on the same service?
-----

Other than the brand new ES750, does ETC offer a product comparable to (but better than) the D4DMX? The SM4-10-A, 4 circuit SmartModule 2, 1x20A Cable In, Dual Edison Out, perhaps?

It is unlikely that one D4 would create enough power line noise while dimming at 33% to cause flicker with the others as this issue is more prevalent as higher currents are drawn. That's why running the EDI rack with bigger loads shows the problem and why I headed down this path. However, if enough D4s dimmed to 33% on all three phases, yes, it is possible. I have seen this happen with several different brands of smaller dimmers, even at lower loads. So, if only all D4s are set to 33% and it works, then try them again with a different power feed and while using the EDI rack. If they do flicker, then D4s probably are always going to be problematic at that dimmed level. Still curious to know what we find.

The SmartModule 2 series of dimming does not suffer from this problem as it was designed and tested to properly handle these types of power line disturbances.

David