CEM Display Freaked

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RikkiHands

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Hi Everyone,
Was vacuuming out sensor racks and at some point the CEM display freaked out--all we did was a standard pulling-out and replacing of D20s, R20s & CC20s. The CEMs weren't even touched.

Happened to 2 out of 3 racks. CEM+ model, so admittedly a bit old, but this sure didn't happen when we vacuumed last summer.

The rack appears to be behaving normally with the exception of the display. Boss hasn't yet decided whether to reset, etc

Anybody experience this before?
 

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Amiers

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Did you try to reseat the CEM to see if it clears it up.
 

MNicolai

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Were the racks online as you did the maintenance or did you power them down, clean the modules, and this showed up when you power cycled them back on?
 

MNicolai

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There's a known issue with the LCD displays on CEM+ modules that they sometimes show gibberish. Not sure what would've caused it when you were cleaning, unless it was already that way and you only noticed after you started cleaning. Assuming this is the same issue you're seeing, the system should still operate fine and the display is just whacked out. If you reset the CEM+ it should clear the problem.

For future maintenance, you should be powering down the racks entirely before removing or swapping modules. There is potential for arc flash that would ignite the air around you, immolate you, and then blow you right off your feet. Turning the a module's breakers off before removing it is not sufficient for preventing this.
 
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RikkiHands

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There's a known issue with the LCD displays on CEM+ modules that they sometimes show gibberish. Not sure what would've caused it when you were cleaning, unless it was already that way and you only noticed after you started cleaning. Assuming this is the same issue you're seeing, the system should still operate fine and the display is just whacked out. If you reset the CEM+ it should clear the problem.

For future maintenance, you should be powering down the racks entirely before removing or swapping modules. There is potential for arc flash that would ignite the air around you, immolate you, and then blow you right off your feet. Turning the a module's breakers off before removing it is not sufficient for preventing this.
Good to hear about the known issue--thanks foer that.

As far as self-immolation warnings: two quotes and several thoughts come to mind: Quote One from a sage Lighting Designer and road guy who's toured all over creation with shows large and small: "When it comes to the House Crew, I never argue procedure. It just pisses off the House Crew and makes it much harder to get the best result possible."

One of several thoughts: Thankfully, it's Theatre, and not Apollo I...

Quote the Second, from "Sex in the City": "Why are we 'Should-ing' all over ourselves?!"
 

MNicolai

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"Why are we 'Should-ing' all over ourselves?!"
Yeah, that's the kind of mentality that gets people killed. Not just in our industry, but in every industry.

Bet if you pick any fatalities in our industry out of a hat and follow the timeline of events leading up to them, there were any number of instances where someone either did or could have said something should be done differently.

Not that the risk arc flash while hot-swapping is that high, but the stakes certainly are. If it happens your chances of survival are not great and if you do make it out the other end of the burn unit, your way of life will be much different for the rest of days.

This is, of course, not to mention any exposure you're inviting upon your employer for an OSHA violation.

It's just like getting pushed around in a one-man lift with the outriggers pulled.

Can you get away it? Probably.

Do lots of people do it everyday? Sure.

Does whatever some prick told you about "That's the way we've always done it" matter when you or your best friend gets killed? Not in the least.
 
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Amiers

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Power down the rack and reseat the CEM. Then boot her back up.

Also what Mike said. Especially if you are doing a full rack dismount. It’s just good practice.
 

MNicolai

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To quote the late David North:

The arc flash potential when swapping a module might be much larger than when unplugging a stage pin under load. Unfortunately, ETC doesn't know what the incident energy available at the phase bars in the rack might be as that is specific to each installation. When removing a module from a rack, you are exposing potential to both electric shock and arc flash and we would like everyone to know that doing any electrical work live is neither safe nor recommended unless you have been trained to do so.

Let's be clear, because these questions have come up before. Sensor rack dimmer and control modules are designed to be hot swapped. You can either swap the modules while wearing the appropriate PPE and following your facility's electrical safety practices as designated by NFPA 70E, or you may simple choose to Lock-Out/Tag-Out the rack.

Also, while no incidents of swapping modules have created an electrically unsafe situation for a system owner, the likeliness of something happening cannot be predicted. Simply think about the possibility that someone has previously dropped a dimmer module which cracked the casting and then placed it back into the rack. The next person comes along to remove the module and that casting piece breaks off the module into the dimmer below or falls next to the phase bar. That's all it would take to potentially be a problem.

I do have stories of other electrical safety issues that have occurred over the years, but fortunately no one has been hurt. So to answer the last question....ETC is spreading this information, and training all their internal and contract technicians, because of legal issues AND our desire to keep everyone educated and SAFE.

Dimmer racks are high current power distribution devices. We need to respect them as such.

If there are additional questions about electrical safety, since I spend a good amount of time on this area, I would be glad to provide answers.

David
ETC
 

danTt

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Pushing the reset button (top left) should fix it as well, without needing to reseat the CEM.

Leaving alone the discussion of whether or not you should power down the racks when swapping individual modules (The arc-flash protection you should be wearing to energize the breaker feeding the rack should be similar to the arc-flash potential from swapping modules), I would certainly power down the racks if I were pulling all of the modules out at once. You're exposing some big old bus bars with a lot current to accidents.
 
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JD

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Now, as to the "why?"
Vacuums and blowers can both create static, especially if the air is dry. Although most newer computer equipment is pretty resilient, I've seen some nice networks get knocked offline while cleaning! At it's heart, a CEM is basically a computer.
Sounds like the data to the display got an accidental "1" added to the flow by static and the display demultiplexer is now "confused."
 

TimMc

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Good to hear about the known issue--thanks foer that.

As far as self-immolation warnings: two quotes and several thoughts come to mind: Quote One from a sage Lighting Designer and road guy who's toured all over creation with shows large and small: "When it comes to the House Crew, I never argue procedure. It just pisses off the House Crew and makes it much harder to get the best result possible."

One of several thoughts: Thankfully, it's Theatre, and not Apollo I...

Quote the Second, from "Sex in the City": "Why are we 'Should-ing' all over ourselves?!"
Well, the exposed phalanges are quite the look, all the rage among the industrially disfigured. /heavy sarc

hot disconnect results.jpg


This worker was injured whilst disconnecting a CamLoc connection that was powered and under load.

DONT DO THIS. EVER.
 

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RikkiHands

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Yeah, that's the kind of mentality that gets people killed. Not just in our industry, but in every industry.

Bet if you pick any fatalities in our industry out of a hat and follow the timeline of events leading up to them, there were any number of instances where someone either did or could have said something should be done differently.

Not that the risk arc flash while hot-swapping is that high, but the stakes certainly are. If it happens your chances of survival are not great and if you do make it out the other end of the burn unit, your way of life will be much different for the rest of days.

This is, of course, not to mention any exposure you're inviting upon your employer for an OSHA violation.

It's just like getting pushed around in a one-man lift with the outriggers pulled.

Can you get away it? Probably.

Do lots of people do it everyday? Sure.

Does whatever some prick told you about "That's the way we've always done it" matter when you or your best friend gets killed? Not in the least.
 

RikkiHands

Member
Joined
Jul 13, 2012
Location
New York
Well, the exposed phalanges are quite the look, all the rage among the industrially disfigured. /heavy sarc

View attachment 15816

This worker was injured whilst disconnecting a CamLoc connection that was powered and under load.

DONT DO THIS. EVER.
"Whilst disconnecting?"

Well there's his first problem.....

Meanwhile, you guys should also look up "Spontaneous Human Combustion" --- happens whilst one is just standing around.....
 

Amiers

Renting to Corporate One Fixture at a Time.
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Location
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Triple post defensive top notch. Take it like a man and stop harassing people that are trying to help you not potentially die.
 

RikkiHands

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Joined
Jul 13, 2012
Location
New York
Power down the rack and reseat the CEM. Then boot her back up.

Also what Mike said. Especially if you are doing a full rack dismount. It’s just good practice.
Yeah... well it wasn't my call. I've been trying to get that across. Really what I was looking for was an explanation for the gobblydegook. Instead, a couple guys are trying to "learn" me about "good practice." Whatevs.
 

GreyWyvern

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Yeah... well it wasn't my call. I've been trying to get that across. Really what I was looking for was an explanation for the gobblydegook. Instead, a couple guys are trying to "learn" me about "good practice." Whatevs.
Good to see that a couple guys are being good, contributing members of this forum by serving one of the purposes! But, you know, whatevs.
 
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