Film-Tech Forum ARCHIVE: Exhaust system automation

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Posted by James Skinner (Member # 7385) on 02-14-2014, 04:44 PM:

We currently have a Christie CP200-M projector with a manual wall switched exhaust system. I would like to automate this so that when ever the projector is running the exhaust system turns it self on. There is a GPIO port on the CP200-M that I am hoping can send the necessary signal? I assume I needs to be some type of relay connected to the GPIO port to control the exhaust system power. I'm hoping some of you have some recommendations on how to do this properly?

Posted by Mark Gulbrandsen (Member # 72) on 02-14-2014, 08:18 PM:

It's a more involved thing to do with the GPIO but it is easy as cake with an automation unit. You will need an appropriate sized contactor for the fan possibly with a low voltage coil in it (leave the manual switch in there too!). Then you will need a lower voltage relay capable of interfacing to the GPIO that will in turn drve the larger contactor coil. There may also be large contactors that are capable if interfacing directly to GPIO logic levels however, I never use GPIO so you'll have to research that part. I suggest you contact an industrial controls company if no one else here chimes in.

Posted by Steve Guttag (Member # 268) on 02-14-2014, 10:36 PM:

The problem with the GPIO method is that it is format specific, not mode specific. While you can track the lamp on/off with GPIO, normally this isn't sufficient since a Christie won't let you light the lamp with the exhaust off...for the CP2000-M...you are in luck because it doesn't have an air flow switch. The GPIO is just an optoisolated output so whatever you hook to better be low-current.

I slicker method would be to use an automation that monitors serial...when the projector is in the "on" state (via the PWR status), turn the exhaust on. When the PWR changes state so the lamp is off...wait x-minutes and then turn the exhaust off.

Posted by Dave Macaulay (Member # 813) on 02-15-2014, 09:40 AM:

You could control the fan directly with a simple SSR (solid state relay) from the GPIO. I'm not sure if the GPIO is default programmed to indicate lamp on - but it's not difficult to set it up for that, if not. I would add a "delay on off" relay as well to run the exhaust a few minutes after shutoff.
I'm with Mark in that I've never used the GPIO for anything (except 3D sync) because we almost always install a Jnior and in my opinion the - probably minimal - risk of blowing a GPIO output on the projector or server (both will be on $$$$ parts) is a consideration. The Jnior uses a relay output rather than the somewhat delicate open collector output from the GPIO.

Posted by Harold Hallikainen (Member # 5405) on 02-15-2014, 09:56 AM:

I wonder if there is some more direct way of knowing that the exhaust fans should be on. I thiught of a thermostat, but you probably want the fans on before the temperature rise. Air flow or pressure in the exhaust seems like it would get confused by the flow caused by the exhaust fan. So, how about a current sense relay on the projector power? When the projector is drawing a certain amount of current, the fan comes on.

Harold

Posted by Sam D. Chavez (Member # 1841) on 02-15-2014, 10:36 AM:

I did Harold's method of a current sensing relay that only turns the fan on after the lamp is struck and it senses the increase in the input current. There is a delay that lets the projector cool before turn off. This installation is inside a planetarium where it's only on occasionally and a noise issue.

The staff electrician found the device so I don't recall the model #.

Posted by Steve Guttag (Member # 268) on 02-15-2014, 12:48 PM:

Again, with Christie, if the exhaust isn't running before the lamp is struck, it won't let you strike the lamp (except the small footprint Christies).

Posted by Brad Miller (Member # 2) on 02-15-2014, 01:06 PM:

Which is exactly how they should ALL be.

Posted by Steve Guttag (Member # 268) on 02-15-2014, 03:29 PM:

Bull. The projector shouldn't make the decision to can a show...the exhibitor should...it is fine for the projector to yell and scream that the exhaust isn't on. It isn't okay for it to shut the lamp off because the exhaust isn't on. It has thermal sensors to determine if it is in danger.

Posted by Sam D. Chavez (Member # 1841) on 02-15-2014, 03:36 PM:

The install I mentioned was a Barco so no issue.

Christie did have lots of issues with sail switches back in film days that could shut down shows for no particularly good reason. There was someone around back then to resolve the issue. Now, no way.

Posted by Brad Miller (Member # 2) on 02-15-2014, 03:48 PM:

Bull to you Steveo. With the ever-declining quality of projectionists these days, many won't pay ANY attention to that silly tail light. As always I'm sure the people you work for are super intelligent and would never ignore a warning, but the rest of us work in the real world. I've heard of this happening a few times in 2013 where a projectionist didn't bother paying any attention to the red light on a Barco and it got so hot the lamphouse got welded into place requiring a tech to go chisel it out and replace parts as the theater enjoyed a down screen for a day or two.

It is NOT acceptable for a machine to "just run". Those Barcos just kept going and going and going without any care in the world that they were committing suicide. If they were at least smart enough to shut down when it reached critical failure I wouldn't argue it so much with you, but that has proven to not be the way they work. I'll take a featherswitch ANY day over that nonsense.

Plus it kills the lamp life. (Amazingly in the above example the bulbs didn't blow to my knowledge.)

It's MUCH better for the show to not start forcing someone to turn their brain on for a few minutes and deal with the issue, then start the show a few minutes late. (I would be ok with a check of airflow in order to ignite the lamp, bu then NOT kill it should the airflow die mid-show though.)

Let's turn this around into something we CAN agree on. It isn't acceptable for a show to stop just because the projector foolishly thinks marriage has been broken when nobody has even been in the booth. I'm getting real tired of seeing THAT happen. Fortunately it isn't widespread.

Posted by Carsten Kurz (Member # 5396) on 02-15-2014, 06:02 PM:

+1

These systems can not run without the exhaust blower if installed that way. Where is the sense to favor an electronic temp sensor when a (properly designed) airflow sensor catches the problem right at the start? Also, how much sense does it make to start a show without the blower, when it will be interrupted anyway after some time due to overheating?

A 'show doesn't start' is the better indicator for a problem than a tail light in an unmanned booth. 200 impatient patrons make an excellent fault sensor.

- Carsten

Posted by Marco Giustini (Member # 4544) on 02-15-2014, 06:34 PM:

I agree. The real world is, unfortunately, going into that direction and red light means nothing today, manned or unmanned booth.

Posted by Steve Guttag (Member # 268) on 02-15-2014, 06:50 PM:

A red tail light should shut a show down...a yellow shouldn't

With your NOC Brad, are you saying you all don't notice that the exhaust isn't running? The projector is kicking out SNMP so no need to depend on the "projectionist."

I've had Christies drop the lamp due to the odd down-draft that caused the sail to bobble...Christie also won't restrike once the air has been satisfied. In the film days, Christie would restrike the lamp since the sail was merely in line with the contactor on the rectifier (when we called them that). In the digital world...one bobble...you are playing to a dark screen.

I live in the real world too...I don't like losing shows. It should be the exhibitor's decision as to if they are going to can a show over a sail switch. I'm not against a sail switch...in fact, I'm in favor of them. I would have less of an issue with the Christie implementation if it had some intelligence behind it. Whey can't it have a "bobble delay" If the exhaust is really off...it will be off 5 seconds later too.

Posted by Mike Blakesley (Member # 26) on 02-15-2014, 07:42 PM:

These things ought to be designed to "recover" automatically when something tiny and quick like a short air drop or a quickie power failure (1 or 2 seconds) happens. The fact that a tiny little "blip" can bring down a machine that's designed to present entertainment to the paying public is an insult to the people who bought tickets and the exhibitor who bought the equipment.

You wouldn't see this kind of crap at, say, Disney World. Of course those people are paying $90 a ticket, so...

Posted by Mark Gulbrandsen (Member # 72) on 02-15-2014, 08:45 PM:

Bullo to all of you! A 75 grand a year Union operator should be making sure it's on... So there!

But from the standpoint of practicality I agree with Harold's idea however, I think I'd have the sensor on the positive DC lamp feed to kick on when the lamp is lit then a timed shut off after 15 minutes. This would actually save on HVAC costs in a lot of plex's.

As for the projector sensing it's own temperature. I agree thats fine and all especially snice this is 2014 and not 1969. NEC's do just that. An air flow switch is so last century these days and not completely reliable. Who kows if the last technician bypassed it because the switch failed. Switches made today have had all the nasty but necessary metals removed and generally speaking are all crap. Current sense is a great idea IMHO and quite easy to do.

Mark

Posted by Brad Miller (Member # 2) on 02-15-2014, 10:43 PM:

Sorry Steve, meant to say yellow, not red. You obviously figured out what I meant though. And remember our NOC offers multiple levels of service beyond what is offered at the other NOCs, and not all customers want everything. However on our Active NOC, yes the lamp is automatically restruck and the alarm issued regardless so the guys at the NOC login and verify everything anyway. That doesn't change the fact Barco's SNMP is a joke and not as useful as you might think.

The bobble delay would be a good solution for Christies.

Posted by Mark Gulbrandsen (Member # 72) on 02-16-2014, 11:21 AM:

Bobble delay went out when Ultimations hit the trash cans! That is so 1980's!

Posted by Buck Wilson (Member # 5885) on 02-17-2014, 12:28 AM:

"Let's turn this around into something we CAN agree on. It isn't acceptable for a show to stop just because the projector foolishly thinks marriage has been broken when nobody has even been in the booth. I'm getting real tired of seeing THAT happen. Fortunately it isn't widespread."

PREACH!!! I HATE this!!!

Posted by Barry Floyd (Member # 385) on 02-17-2014, 10:39 AM:

I built something similar to what Steve describes last summer to automate our exhaust fans at the drive-in. I've got Barco DP2K-23B's with GDC SX2000AR servers. We're using a simple automation panel built by Kimber Labs (sold by American Cinema Equipment)called the KLA-1, and using the GPIO interface from the IMB on the projector.

We basically used two relays and a contactor to do the job. My GPIO automation send a pulse signal (triggered by the server) to the automation panel which in turn triggers a latching coil relay to engage the second relay. (The second relay is a "DELAY OFF" relay that has a 15 minute delay off hold time). Once triggered, the relays latch and hold the contactor energized and keep the exhaust fans running. Once the automation triggers the "EXHAUST FAN OFF" sequence, the first relay unlatches, and in turn lets the second relay begin it's 15 minute "DELAY OFF" sequence. What it does is that it keeps the exhaust fan running for 15 minutes after projector shutdown to gradually cool the bulb. I built two of these last year for my drive-in, and they work absolutely perfectly. I installed a manual override switch in mine so I can turn on the exhaust fans without the automation if needed, and I also installed a ceiling mounted indicator light that lights when the circuit is engaged so I can tell with a quick glance into the projection booth that the exhaust fans are on.

I've got the "EXHAUST FAN ON" automation trigger as the very first cue in my playlist (before the bulb even lights)- so it's got time to come up to speed before the projector even starts, and the "EXHAUST FAN OFF" trigger is the last thing in the playlist at the end of the night.

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2014, 11:54 AM:

Thats a sort of round about way to do it that does work. However, I prefer not to rely someone's home made automation but rather an off the shelf readily available UL listed item. A much easier way would be to use a Current Sense Relay This would simply be monitoring one leg of the AC going to the xenon rectifier section of any DLPee. It has a user set operating window so it would work with just about any type projector out there. It is small enough to even be built into all in one projectors if necessary. I would still use a larger motor rated contactor to switch the actual exhaust motor on and off though. Note that they also supply a version with a remote current sense transformer in case there isn't enough room inside a projector or if you just don't want the whole relay in there.
CR Magnetics Spec Sheet

Just about all industrial control manufactures make these types of relays in some sort of way shape or form. Seimens, Panasonic, Crouzet, etc.

Mark

Posted by Christian Hove (Member # 6743) on 02-17-2014, 02:08 PM:

Hi James,

I wanted something similar on our Christie CP2220's and and as others has written the projectors (our at least) refuses to power up if the fan is not running and report an error (exhaust interlock failure as far as I remember).
I do not know if your projector has the same connectors, but ours have a 3D port (DB15) that features some useful outputs.
Among these there exist a +12VDC/1A supply connection for the 3D emitter. As soon as the projector is turned on, this output becomes active. I successfully use this output for driving a relay that turns on the exhaust fan.
Another output is active when the projector enters 3D mode - I plan to use this for turning the 3D IR emitter for our glasses on and off.
If you are interested I can post the details for wiring things up.

Cheers,

Christian

Posted by Carsten Kurz (Member # 5396) on 02-17-2014, 03:07 PM:

All projectors should have a trigger signal for this built in, as closely as possible coupled to bulb running status, and with a 10min shutdown delay.

- Carsten

Posted by Rick Raskin (Member # 1561) on 02-17-2014, 03:58 PM:

If these things are so mission critical why isn't there redundancy built into the exhaust system? Exactly how pervasive is the problem?