Power Supply Thoughts. Curious on other peoples set ups in the booth.

[Brian Mendelssohn]

Power Supply Thoughts. Curious on other peoples set ups in the booth.

I'm tired of UPS fails, power outages, etc. I get an occurrence about once a month. Financially, that's about $1000 in ticket reimbursements, but it creates a bad experience also. I sharpened my pencil and went to work to solve this problem. I've gone down many paths, and here is what I came up with. Would love feedback.

Goals:
- Power Outage, to use battery to finish the current film (120 minutes minimum... maybe LOTR extended is playing)
- UPS fail, no outage at all
- Brown outs, no outage at all

Not a goal:
If power failed for hours, oh well.

My system is about $5k for a small screen and $9k for a large one. This is significantly more than the standard UPS for the racks and maybe a PDU ($600). Do people use generators? Thats about the same price in total.


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[Randy Stankey]

I like Mark G.'s idea best:

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[Marcel Birgelen]

Have you tallied how much power you're using when both rooms are running at the same time? Maybe it's simpler to install one big UPS, an STS/ATS and a suitable generator as backup. Generators usually can also be rented. How much such a setup will cost is highly dependent on the amount of power you need, but the generator route is often more feasible with higher loads than trying to bridge the gap with batteries.

[Mark Gulbrandsen]

UPS's require strict maintenance to keep them running. Battery replacement at least every four years and cleaning the dust out of them every two years. Cleaning them properly likely entails removing the top cover to be able to do that. Overall, I have not had that much trouble with UPS's, but I installed Tripplite everywhere. I know people in the broadcast bidness that hate APC UPS's. So the issues may be more brand related than anything.

[Brian Mendelssohn]

I only use Tripplite myself, and are especially loving their new lithium product! I'm thinking more and more about batteries over generator simply because the for my need, it doesn't take much batteries to finish a film. A typical small Christie Laser Projector maxs out 700 W 240V, which is manageable. Also, I've had UPS fails (even with tripplite), so a ATS does come into play. A good generator is sooooo expensive to handle these loads, especially on with auto start, etc. The investments seems too high.

[Steve Guttag]

Some food for thought...

I use UPSes in just about every installation. Traditionally, I've used Tripplite. I had good luck with Tripplite...until the SMART (line interactive) changed over to the new digital display. Those units seem to have a problem with their charging circuit as I've had multiple pre-mature battery failures...changed the batteries only to find that the UPS wasn't really charging the ones I just put in. So, I have no interest in that model Tripplite anymore.

The Smart Online (SU series...e.g. SU1500....) those have had a MUCH better service record and they are zero transfer time and double-conversion so the protected equipment never sees a glitch. I've had maybe one fail in the nearly 200 installed.

Tripplite has one quality that just ticks me off though...when their batteries fail, the UPS plays possum. It doesn't just light the change battery LED (which it does, at first) but the next time that UPS loses power, it simply goes dead. No LEDs, no noises, no beeps...it just appears completely dead. Change the batteries and it's all happy again! This is true of both the SMART and the SU series (And the SMX, if you are into the 220V SMART series).

Because of this "feature" of Tripplite, we started to make our own transfer switch (just a relay with suitable contacts for the load) so if the UPS dies, (for any reason), the city power takes over as fast as the relay can discharge (very fast)...with that scheme, bad UPSes have been effectively masked. However, now people have bad UPSes and are unaware until the next power glitch. Perhaps, with Q-SYS, we'll start monitoring the UPS output and if it disappears, it will alert us/customer. One of the tricks is having equipment that can take such stimulus to let you know that you are on your backup.

Due to the sudden no-power issue, we have been trying out APC (equivalent models as Tripplite...they name them essentially the same). The APC keeps power going, even if the batteries fail. On a recent installation, I used an off-the-shelf ATS from Cyberpower (the Tripplite and APC ATSes are obscenely expensive). The ATSes seem overly complicated for what they are and, we found they get fooled easily with brownouts. They'll see a line-interactive UPS switch to battery power...drop over to city power...causing a power glitch and then switch back to UPS power with another glitch and possible breaker pop. I can't stand it when the backup/protection system is the cause of failures!!!! I will say that the APC UPSes have, themselves, performed flawlessly in a couple of different sites. They are about 20% more expensive than Tripplite.

Another thing to consider as you go for massive UPSes (something that can hold the remainder of the show...which also means the sound and the lighting because you'll have emergency lites lit once power goes out)...that bill for batteries every 3-5 years is going to hurt. The more capacity you have, the more expensive it gets. I will say, with Laser projectors, the possibility of putting a UPS on them for the light source too has become much easier. For a 23,000 lumen Barco SP4K-25C, you still just have 16A single phase 208 (and probably less since it is rated down to 200V).

[Marcel Birgelen]

I don't think that running the entire show on batteries will be realistic, budget wise. You can have a 90 kVA generator for anywhere between $10k to $15k. That kind of power is probably more than enough to light-up the entire building. Most professional no-break setups for e.g. datacenters and hospitals also use UPSes that can bridge just a few minutes, backed by one or more generators.

A generator will need a few seconds to be able to come on-line and sync phases. It's that gap you need to fill with battery power.

[Steve Guttag]

And you can sell that excess power to Texas! What? Too soon?

I would agree though, at some point, if this is really an issue, a Generator is the right fix for the problem on top of conventional UPSes to cover the gap between power-out and generator start time. However, again, if you want the audience to be oblivious to the power outage...you are talking about powering lights and amplifiers too. If you don't mind a brief pause, then just keeping the server/projector going and possibly the sound electronics will suffice.

With the right automation and equipment you could even have a PNG file come up when the power drops enough to be on UPS to tell the audience that the show will resume in a minute and to stay in their seats.

[Carsten Kurz]

It's ridiculous that off-the-shelf UPS do not have the simple functionality to bypass themselves in case of failure. I mean...
I have experienced many situations where the only actual unplanned interruptions have been caused by failing UPS, not mains power dropping out.

[Leo Enticknap]

IMHO, the amount of load is going to be the key to viability or not of doing this with batteries alone.

The variables you can't do anything about are projectors and the power amplifiers. Keeping a Barco DP4K-32B with a 6.5kW bulb in it running for two hours (around 7kW) will require a lot more battery power than an NC900 with the lamps running at minimum power (around 500w). Likewise, a 900-seat Atmos auditorium will need a lot more amplifier power than a 15-seat screening room in a post house.

Would a solution based solely on battery UPS units even be viable for the worst case scenario - a big, xenon-lit screen and 70-80 amplifier channels?

[Marcel Birgelen]

And you can sell that excess power to Texas! What? Too soon?

Well, if you're located in Texas, I guess you could. I've heard the regulations there are very open, so everybody can probably start their own power company with a bunch of solar panels and a windmill. If you're not located in Texas, that will be one heck of an expense for a beefy power-line though.

I would agree though, at some point, if this is really an issue, a Generator is the right fix for the problem on top of conventional UPSes to cover the gap between power-out and generator start time. However, again, if you want the audience to be oblivious to the power outage...you are talking about powering lights and amplifiers too. If you don't mind a brief pause, then just keeping the server/projector going and possibly the sound electronics will suffice.

With the right automation and equipment you could even have a PNG file come up when the power drops enough to be on UPS to tell the audience that the show will resume in a minute and to stay in their seats.

Usually, when the power drops, the emergency lightning should come on. So nobody should sit entirely in the dark. You can easily do a few minutes without HVAC too. In order to use the projector to inform the audience, you'll obviously also need to power the lamp/light source via a UPS. Maybe you could use some smaller, secondary projector to come on and project a message. It will depend a lot on the screen size how effective this will be, but you won't need anything fancy for just a high-contrast message.

I guess the biggest challenge will be the part of the automation that restarts the show, after the generator comes back on. Maybe this is something that should be triggered manually, so the projectionist/manager/popcorn artist on duty can check if all systems are ready to go, as in that all amps are back on-line, the lamp (if not on UPS) has ignited successfully, etc.

Another interesting thing to get right is to switch-back from generator power to mains. If you switch back too early and the grid goes back off-line again, for example, you risk exhausting your UPSes to a point they won't be able to fill in the gap. Depending on your experience with the local power grid, it might even be best to switch back manually, after the shows are over.

[John McCulloch]

Often when the power fails it causes nearby security alarms to start sounding for a while, because they assume the power cut to be tampering.
Next time the power goes out it's worth checking to see if you can hear any noise from inside the theatre. You'd hate to spend the money on UPSs to keep the show going, but find something outside your control interrupts it anyway and you're still issuing refunds.

Also - don't forget that for anything other than a quick interruption you'd need to think about powering general lighting, POS systems, fire alarm etc so a whole-building UPS starts to look necessary for keeping the show running.

[Steve Guttag]

We've been monitoring city power for just about the entire DCinema era. That is, there is a 120V relay that is essentially plugged into the the same power as that which feeds the UPS. If that relay drops, the automation (Eprad eCNA) can then execute an appropriate Macro...which we pause the show right where it is since even with the projector (electronics) and server being up, you don't want the show to progress without sound (or an image). At first, we had it set up to automatically restart once the power came back (Barco projectors can be set to restore the lamp state it was in before the power failure, so the lamp would be lit). However, we found that was a bad plan since you don't know where the audience may be. Many will take the opportunity to go to a bathroom break or otherwise tax the staff with questions they cannot answer (when will the power be back?). Instead, we provide for a "restart" that resumes the show right where it was (and they'll see it as a freeze frame until it starts so they know they aren't missing anything). Upon hitting restart the lights, sound...etc. are all put back into the feature setting and the show resumes.

[Marcel Birgelen]

I indeed think that, when you can't guarantee a completely interruption-free show with a power outage, it's better to manually restart. The audience also being a factor. Maybe rewinding a minute or so isn't a bad idea either. For a few locations were we implemented intermissions, we rewind the movie for 15 seconds. While this might bring you right back into a scene, the audience recognizes it and seems to generally like it, because they know they're not missing anything.

Often when the power fails it causes nearby security alarms to start sounding for a while, because they assume the power cut to be tampering.
Next time the power goes out it's worth checking to see if you can hear any noise from inside the theatre. You'd hate to spend the money on UPSs to keep the show going, but find something outside your control interrupts it anyway and you're still issuing refunds.

Also - don't forget that for anything other than a quick interruption you'd need to think about powering general lighting, POS systems, fire alarm etc so a whole-building UPS starts to look necessary for keeping the show running.

Fire alarm should have separate battery systems, the same goes for emergency lightning. If you opt to go for a UPS for the important systems and a generator for the rest, everything else should be back up within a few minutes after the power outage started. A generator usually needs about anywhere between 7 to 30 seconds to come on-line. Then, it depends a bit on how long it takes for separate systems to boot. Normal lightning usually kicks in right after the generator is on-line, POS systems and other computer-powered systems will probably take a few minutes to go through their cold-boot cycle. Some systems may need longer, because they'll performing consistency checks.

In the end, you don't need to put the entire building on UPS systems. Even datacenters and hospitals don't usually put everything on UPS. Power hungry stuff like HVAC systems often are only backed by generator power, because the impact, when those systems are off-line for a few minutes, is usually pretty minimal. My father used to work for Air Traffic Control, those systems are as redundant as you can get them and even they didn't put their cooling systems on UPS. They made sure that everything that needed cooling in order to work, was cooled to such a temperature, that there would be a window of about 20 minutes, before anything would start to overheat, even with HVAC completely down.

[Scott Norwood]

One potential problem with the UPS idea: most UPSes are designed for computers and don't output a normal AC sine wave when on batteries. This "dirty" power is fine for computers, but may not be for sound equipment, video projectors, automation systems, etc.

I've heard of places like hospitals (which need uninterrupted power) using things like motor-generators with giant flywheels to provide continuous power if the street power fails and the generator(s) needs time to start and stabilize. This seems like overkill for a cinema, but maybe not for locations with regular power outages.