Overheating Dimmers

[Spongebob]

Warning: You're going to be very confused when trying to understand exactly what my problem is because I have NO idea what kind of equipment we have.

Ok, here goes.
For the past three years in my experience with the system, we've never had this problem. For the past 10 years of our TD's experience with the system, he's never come across this problem. However, when on my first show as SM, the lights have been doing this funky thing where they just go on and off. The lights turn off then turn back up. We're pretty sure it's something with the dimmers, because they often overheat if there's no fan circulating air in the room that they're in. However, we've never had such a severe problem with it, because now we need one fan pointed directly into the dimmers, and a fan in the room, and both doors open. (Description of the room: a school bathroom turned into storage of costumes. Narrow entrance, but the fan sits at the entrance pointing the inside, and to my knowlege the number of costumes hasn't changed). Another small problem we had was that the board and the lighting system would shut down completely, and then restart itself. That problem stopped when we took the board out and plugged everything back in. However, it's now become a regular ordeal at every performance for the lights to have their dim attack.

^see, confusing.
Random things I think will help you understand:
-our lights are AINCIENT. we have pretty much the oldest ellipsoidals and fresnels that anyone could ever have. When dinosaurs were done with their productions, they gave their equipment to us. Some of them are dusty, but we've cleaned most of them.
-Our "theatre" is a black box theatre. It seats 70, and if we add in extra chairs it seats 100 (ps. we rarely fill it up....)
-our board is on the same level of the lights. OH and we don't have a catwalk. We can pretty much just get a regular ladder and focus lights like that. I'd say it's 10ISH feet off the ground.
OH SPEAKING OF THE LIGHTBOARD, it smells like fire all the time
^ok I realize that's not a good thing. It's only sometimes when we have all the lights on and we're testing them, we just get a burn smell. it goes away...eventually.

So, MY QUESTION IS:
In your experience, with crappy equipment and abuse of the equipment, what are some overall factors that could be contributing to this problem?

My number one theory is that either I'm cursed, or the theatre hates us because we have no talent, acting wise

*my technical director, to my immediate knowledge, did not get a degree in anything, all he has is many years of experience.

 

[derekleffew]

Regardless of the rest of the lighting system, you have modern, quality, industry standard dimmers. ETC Sensor. Model# SR24, if I'm not mistaken.

Evident from your photo:
1) For proper ventilation, there should be no empty slots or missing modules in the rack. AirFlow Modules (AFMs) exist to fill slots where the dimmer isn't wired. Even if a dimmer module isn't functioning properly, it should be left in the rack with its circuit breakers turned off.
2) The door to the rack should be kept closed at all times.
3) It should not be necessary to have a fan pointed at the rack. The room containing the dimmer rack should meet the following criteria:

Ambient temperature between 32°F and 104°F (0 – 40°C)
Humidity between 30 – 95% (non-condensing)
Altitude below 6500 feet (2000 meters)

4) It's likely the filter in the door has never been cleaned. See KnowledgeBase: Sensor CEM Displays "Airflow Errors" and May Flash Loads - Electronic Theatre Controls .
5) [-]Hard to tell from the photo (attached below in correct orientation), but it looks like there's a shelf unit made of 2x4s sitting directly on top of the dimmer rack. [/-]

Is there sufficient clearance (10 inches minimum) above the rack?

[-]Since the fan exhausts heated air out the top of the rack, this is obviously a major issue.[/-] [EDIT: Nevermind.]

See also the threads:
Sensor Dimmer Rack Air-Flow Problems
Something with the dimmer rack...

If all else fails, give ETC Service a call at 1-800-688-4116 and they'll be glad to assist you in solving the problem. (It might be prudent to write this number on the dimmer rack.)

 

[Les]

Great post, Derek!

One thing I might add, if I may. All that clutter around the dimmer rack needs to go away -- yesterday.

 

[DanAyers]

Classic signs of over-heating.

They do much the same thing if someone tried to cover-up the fan noise by throwing extra curtains on top also.


All items need to be away from the rack at least 10" from the top, 6" from the sides and 17" from the front. All modules need to be inserted. The door needs to be shut. The door contains a air-filter. Ensure this filter is clean. Since it is nylon you can wash it off, though spraying it with air works well also. I'd recommend you also spray all the dust off each module. Use an air-compressor, or it takes about 2 large can's of canned air.

the advice above was also good.

Here's a link to the installation manual which may also help you.
http://www.etcconnect.com/docs/docs_downloads/manuals/Sensor__UL_Install_Guide_RevB.pdf

Hope this helps

Dan Ayers

 

[MPowers]

What derek said, Get that thing off the top of the rack!!!! air flow mod, close the darn door!

The burn smell is usually caused by dust and lint build up in the individual dimmer modues. They desperately need to be cleaned. That means removed from the rack and cleaned by a competent person. Call an ETC technician.

Michael Powers, Project Manager
ETCP Certified Rigger - Theatre
Central Lighting & Equipment Inc.
675 NE 45th Place, Des Moines, Iowa, 50313

 

[FMEng]

What derek said, Get that thing off the top of the rack!!!! air flow mod, close the darn door!

The burn smell is usually caused by dust and lint build up in the individual dimmer modues. They desperately need to be cleaned. That means removed from the rack and cleaned by a competent person. Call an ETC technician.

I'm not totally clear from your description if the burning smell is coming from the console or the dimmer rack. Your problem is likely caused by lack of cooling the dimmers, but it could be caused by the console as well.

If the smell is coming from the console: It is a pretty reliable indicator of a damaged component that will lead to problems now or later on. It should be checked out by a qualified technician.

Either way, the ventilation of the dimmer rack and room needs to be corrected. Starving them of proper air flow and/or overly high ambient temperature will shorten the life of the system.

 

[starksk]

... 5) Hard to tell from the photo (attached below in correct orientation), but it looks like there's a shelf unit made of 2x4s sitting directly on top of the dimmer rack.

Since the fan exhausts heated air out the top of the rack, this is obviously a major issue.
...
If all else fails, give ETC Service a call at 1-800-688-4116 and they'll be glad to assist you in solving the problem. (It might be prudent to write this number on the dimmer rack.)

Derek, The photo is actually upside-down (note the CEM Classic LCD orientation).

However, Spongebob, Derek's advice is sound and exactly the first things that we would cover with you when you call.

There are many things that should be corrected in that photo. The biggest one being that you should replace the missing modules back into the rack ASAP. This is not only a matter of airflow (which is likely the cause of your problems) but also because at the moment, that rack is very dangerous. You can accidentally touch the live buss bars which are providing the power to the remaining modules in the rack. A standard SR24 is usually fed with a 400A feed. That creates a very real danger for your person as well as a fire hazard.

I recommend that you power down the rack, remove the dimming modules and vacuum them free of dust. Then remove the CEM and use compressed air to blow off any dust and crud that may be residing on it. Vacuum out the rest of the rack so there is no dust or dirt including and especially the filter. Put every module back in to place, place the CEM back in the rack, close the door, and power the rack back on.

I am sorry if my tone is a bit harsher than usual, but in this situation I do not want to see you or anyone else hurt by this very real hazard.

 

[derekleffew]

Derek, The photo is actually upside-down (note the CEM Classic LCD orientation). ...

Ya know, I thought there was something wrong with the direction of the door swing! My property has lots of SR6, 12, 24, and 48 racks. But frankly, since they are so problem-free, I couldn't remember exactly. Sorry to lead so many down the wrong path.

Attached photo in post above has been corrected.

Still, I wonder what the AHJ would have to say about storing fabric, wood, and other fuel near an electrical enclosure? NEC 110.26 referenced here: http://ecmweb.com/nec/code-basics/electric_code_basics_4/ seems pertinent.

 

[Spongebob]

Thank you all so much for your advice! I never knew so many things were wrong with the dimmers!

Questions/Comments:
1. Sorry about the picture. It was a last minute "oh hey, I think I took a picture of the fan hanging from the ceiling because I thought it was funny!" So yes, we hung a fan from the ceiling and pointed it directly toward the dimmers for air flow (not my idea, TD)
2. The door is open, again, because of the TD. He claims, again, helps air flow.
3. I don't know what's up with the missing modules. I'll ask, I know that two of our dimmers don't work, but I wouldn't know why there would be missing modules.
4. THE MOST helpful piece of advice you all suggested was to call a technician. The only major problem posed is that our department barely has enough money to produce a musical next year, let alone have a technician come and check out how many laws we're probally breaking. Our biggest problem is basically the proffessional help. My technical director is like...30 and learned everything by common sense (and I do the same, but I'm moving on to college to actually get trained).
5. I really do wish we had another place to store everything. My teacher/director is a pack rat (but so am I). I do realize the need to give the dimmers space.

Again, thank you SO MUCH! I never have any help besides the TD and I'm always afraid to bring up these things because he'll yell at me.

I'll be sure to update you guys so that you know that i'm not going to set my theatre on fire

 

[n1ist]

You may want to point your TD to this thread, and make the following clear to him:

- In the current state, someone could be killed. Think what would happen if someone accidentally sticks something conductive in the space between the dimmer modules, something like a falling coat hanger or a metal rod.
- Overheating the dimmers like this will shorten their lifespan.
- Storing flammable material near overheating dimmers can cause a fire. That's why the NEC prohibits overcurrent devices and panels in a clothes closet.

Calling in a tech seems to be a cheap alternative to any of the above.
/mike

 

[MNicolai]

2) It doesn't. If you clean your filter held within the rack door it should not limit air flow. This filter is what helps reduce the amount of dust and particle build-up on your dimmer modules, and helps keep them cooling better. The proper use of this filter will also reduce that weird smell of burning dust.

3) Unless the modules have been sent off for repair or are being immediately replaced, they should remain with the rack. At the very least, they do no harm. You can keep inoperable modules in the rack with their circuit breakers turned off and they will not create problems. Otherwise, airflow-modules aren't that expensive and you can pick some up for not very much at all.

4) If you can't afford it, then you have to settle for things not working. If you choose not to do it, then you also have to settle for knowing you could be endangering yourselves and those around you. Right now your dimmers might just be overheating, but if you've got lots of combustibles near your dimmer rack, if something should start on fire that's on your head.

Dimmer racks require preventative maintenance, just as rigging, consoles, and many other systems in theatres. This can usually be handled through normal labor, but sometimes it requires some money and help from professional field service technicians. A properly adjusted budget takes this into account. Things will break, you can repair them right away, or you can wait for your entire system to go kaput. Expect it to degrade the quality of performances, though, as you begin to be able to turn on fewer and fewer lights.

5) Almost all theatres want more storage space; I'm sure if you go through you can find some things to throw out. People like to hold onto things that look good, cost money, or "might be used again on a later date." Often enough, these things sit in storage for a decade or so without being used and someone finally mans up and throws them out. Seriously ask yourself when looking at the things in that room, "How much of this stuff are we going to use in the next 3 years?"

 

[derekleffew]

... I never have any help besides the TD and I'm always afraid to bring up these things because he'll yell at me. ...

This bothers me immensely. A student should never be fearful of a teacher or staff member yelling at them. While it has never been Control Booth's intent to get between a student and teacher or contradict what is being taught, sometimes it's inevitable, and warranted.

You're afraid he'll yell at you? Who yells at him when lights flicker during a performance, not to mention the life-safety aspects?

I don't care if the person has a PhD from Yale and thirty years of professional experience or no degree and ten years of questionable experience, a dimmer rack should not be allowed to get to that condition.

Here's an idea: Call up the closest college with a theatre dept. Ask for the Lighting Designer or Technical Director. Ask the person if he or one of his advanced students would be willing to come to your High School and show you how to clean your dimmer rack for free. Being in Los Angeles, it's not like you're in an isolated area with no competent people around. Anyone reading this with the desire and ability to help, PM Spongebob. Cleaning a dimmer rack doesn't take a great deal of skill or experience, having done it just once, under the supervision of a Qualified Person, usually provides adequate training. See also the thread Three dimmers won't turn off. While the rack in that discussion is a different brand than yours, many of the same principles apply.

Also, a phone call to ETC's Support number (above) is always free (the solution may not be however). starksk's sole mission in life is to answer that phone and assist customers. Don't hesitate to use it/him.

Good luck. No one should have to suffer with flickering lights when the solution might be as simple as half an hour with a vacuum and a $5 can of air. By the way, the manufacturer says dimmer racks should be cleaned every 400 operational hours (any time the dimmer rack's fan is running is an operational hour.) That's somewhere between every two weeks and every three months.

 

[Cashwalker]

(any time the dimmer rack's fan is running is an operational hour.)

I don't think anyone has asked if the fan is running in the first place.... Cleaning the filter and closing the door won't help, if the the fans aren't sucking air.

I had a customer with a rack-mount computer sitting with the case open, and a 24" box fan strapped on. The case fans died, but since the system was constantly on, there was never time for "maintenance" much less repair of the fans. Well, until I came to fix one of the telecom cards in it....

 

[Chris15]

For safety and liability reasons, this thread has been closed and some posts removed.

In accordance with Controlbooth's safety policy, our advice is that in matters surrounding electricity particularly, in many cases if you need to ask the question you should not be attempting the task.

If you do choose to engage in preventative maintenance tasks,
POWER DOWN YOUR RACK FIRST,
follow Lock-Out/Tag-Out procedures, use applicable PPE, and be supervised by a Qualified Person.

Note especially the advice of the ETC representative regarding the missing modules.