I've always read you should have separate electrical circuits for your projector and equipment. Nobody has ever explained why. I know the projector, equipment and subwoofers need to be on the same phase to eliminate ground loops, but I don't know why you need separate circuits. Can someone please enlighten me?

Thanks!

Dave

If you've ever heard a loud pop through your speakers because your refrigerator is on the same circuit and the compressor kicked on, or if you've "seen" 60 cycle hum in the form of a slowly-moving horizontal line on your projection screen, you know why. A separate circuit doesn't cost much, either.

Thanks Paul. That makes a lot of sense.

Dave

I've always read you should have separate electrical circuits for your projector and equipment. Nobody has ever explained why. I know the projector, equipment and subwoofers need to be on the same phase to eliminate ground loops, but I don't know why you need separate circuits. Can someone please enlighten me?

Thanks!

Dave

Dave, it's a VERY good idea to keep you projector/equipment on a dedicated circuit, for the reasons from others and to allow your a/v equipment to have the enough "juice".

I would suggest for your projector to have a dedicated ROMEX run to a surge protector/UPS battery back up in the event of a power outage and the projector needs power in that case to stay on until you shut it down to protect the bulb after thge fan cools it off.

ONE inexpensive way to run a dedicated ROMEX run so you can connect that projector receptacle is with a product I purchased, Powerbridge. It's a specially designed a/c power inlet/outlet system that comes all as a one complete kit and in different wall plate colors to let you have power from a surge protector to the ceiling/wall receptacle. You can install it yourself or any electrician can install it. Check it out. www.powerbridgesolution.com

Just a suggestion to help keep to code and protect your expensive projector from power damage. good luck..

Sometimes dimmers can also reak havok on your AV equipment. They should be on a seperate circuit.

There are plenty of people here that run (1) dedicated circuit breaker for the projector and then a couple more dedicated ones to outlets in their equipment rack. Maybe a bit overboard, but I guess it depends what you are running. In my case, just a standard receiver (7x105W), DVD player, sat box and projector. I just have one dedicated circuit breaker for the equipment rack and projector.

Another good reason is that most of your equipment being on a different circuit breaker is really important for a projector that cools after it turns off. If turned off immediately, the projector and/or bulb could be damaged.

I would suggest for your projector to have a dedicated ROMEX run to a surge protector/UPS battery back up in the event of a power outage and the projector needs power in that case to stay on until you shut it down to protect the bulb after thge fan cools it off.

ONE inexpensive way to run a dedicated ROMEX run so you can connect that projector receptacle is with a product I purchased, Powerbridge.

Here is one simple way using a two bucket rack and pulling the projector romex run to the side of an outlet next to the breaker panel.

http://i23.photobucket.com/albums/b393/bigmouthindc/DSC00997.jpg

Don't ask about the black spot. There is a Cox cable installer who would rather not talk about his last day on the job. Almost his last day on earth.

I would suggest for your projector to have a dedicated ROMEX run to a surge protector/UPS battery back up in the event of a power outage and the projector needs power in that case to stay on until you shut it down to protect the bulb after thge fan cools it off.That isn't true. A projector doesn't need a UPS. The projector will cool just fine via natural convection. Problems will occur if the bulb gets struck while it is still hot. If you unplug a projector while it's on and then plug it back in, most of them will turn the fans on to cool it off. During this time you can't turn it back on even if you want to.

That isn't true. A projector doesn't need a UPS. The projector will cool just fine via natural convection. Problems will occur if the bulb gets struck while it is still hot. If you unplug a projector while it's on and then plug it back in, most of them will turn the fans on to cool it off. During this time you can't turn it back on even if you want to.

I think that this is probably a minority opinion. Every other post I've seen dealing with projector UPS systems in the past year has indicated that bulbs require fan cooling in order to cool off properly.

-drin

I think that this is probably a minority opinion. Every other post I've seen dealing with projector UPS systems in the past year has indicated that bulbs require fan cooling in order to cool off properly.

-drinWhy would it? Lets think about a power failure for a minute. When running the fan keeps the lamp at a certain temperature determined by a balance of input power and fan cooling. So, the power goes out and the lamp temperature drop slowly via natural convection. The lamp isn't going to get any hotter once the power goes out than it was before the power goes out, so where's the problem? Clearly the lamp can handle the temperatures seen during cool down because it runs at that temperature or hotter all the time when powered. :confused:

Why would it? Lets think about a power failure for a minute. When running the fan keeps the lamp at a certain temperature determined by a balance of input power and fan cooling. So, the power goes out and the lamp temperature drop slowly via natural convection. The lamp isn't going to get any hotter once the power goes out than it was before the power goes out, so where's the problem? Clearly the lamp can handle the temperatures seen during cool down because it runs at that temperature or hotter all the time when powered. :confused:

Except it's in a box.

Why would it? Lets think about a power failure for a minute. When running the fan keeps the lamp at a certain temperature determined by a balance of input power and fan cooling. So, the power goes out and the lamp temperature drop slowly via natural convection. The lamp isn't going to get any hotter once the power goes out than it was before the power goes out, so where's the problem? Clearly the lamp can handle the temperatures seen during cool down because it runs at that temperature or hotter all the time when powered. :confused:

The problem, as stated by Fatawan, is that the bulb ISN'T simply a bulb. It's a cartridge which includes the bulb and quite often associated circuitry. A unit like this will NOT cool evenly via convection, which can lead to damage to the components therein, hence the need for a UPS.

I'd say the cost of a UPS more than offsets the cost of a new bulb, when bulbs run upwards of $400 apiece.


-drin

Except it's in a box.That doesn't matter. As soon as the power goes out the input power to the box = 0, so there is no heat building up that isn't dissipated. The projector will cool naturally (perhaps rather slowly) by convection and radiation.

The problem, as stated by Fatawan, is that the bulb ISN'T simply a bulb. It's a cartridge which includes the bulb and quite often associated circuitry. A unit like this will NOT cool evenly via convection, which can lead to damage to the components therein, hence the need for a UPS.

I'd say the cost of a UPS more than offsets the cost of a new bulb, when bulbs run upwards of $400 apiece.


-drinI might perhaps subscribe to the idea that something else in the projector could be damaged by the transfer of heat to it from the other hot parts, but I find it impossible to believe the bulb will be damaged by being hot (but still cooler than when it is powered running and being cooled by the fan).

If it's so essential, why doesn't the manual for these projectors recommend a UPS?

That doesn't matter. As soon as the power goes out the input power to the box = 0, so there is no heat building up that isn't dissipated. The projector will cool naturally (perhaps rather slowly).
Actually, no. Because ventilation has ceased, there's a significant build-up of heat in the projector which nicely cooks the interior. Projector cabinets are not designed for convective cooling. If you want to test this, get a temperature probe, place it in the cabinet, measure, then pull the plug. Temperature in the cabinet will very rapidly rise.

Actually, no. Because ventilation has ceased, there's a significant build-up of heat in the projector which nicely cooks the interior. Projector cabinets are not designed for convective cooling. If you want to test this, get a temperature probe, place it in the cabinet, measure, then pull the plug. Temperature in the cabinet will very rapidly rise.Air temperature in the projector will rise, but the bulb temperature will not. The hottest item in the projector will not get hotter without any additional input power.

I want to thank eveyone for their responses. I also want to say "Can't we all just get along?".

Dave

I also want to say "Can't we all just get along?".


Where would the fun be in that?

I've been looking at building essentially what the PowerBridge kit provides. I'd more than happy save about $20 by buying the parts myself. I'm going to keep on searching around... $50 + shipping seems way too much for plastic and a few metal blades. <sigh>

Air temperature in the projector will rise, but the bulb temperature will not. The hottest item in the projector will not get hotter without any additional input power.

Was there any resolution to this? I'm considering whether I shld put my projector on a UPS and the above makes sense and suggests no.

Simple thought experiment - if fans are not necessary in a projector, then why are they in there? When I turn off my projector (and the previous one) the fan runs for a few minutes. It is true that the bulb is the hottest part, and once the power is gone, the bulb will not get any hotter, but what about the rest of the projector? That is why the fans run after the projector is "off" - to cool rest of the projector parts - electronics and optics tend not to like being cooked.

FYI guys, I ended up buying this for about $14, which essentially gives you what you want in order to create an 'extension cord' to your PJ. You put thi on the UPS side, and you put a regular socket on the PJ side. Wired with your regulaer electrician grade wire....

http://www.amazon.com/gp/product/B00074USHY/105-1658463-7850026

http://ecx.images-amazon.com/images/I/314H1AEBQPL._SS500_.jpg

Simple thought experiment - if fans are not necessary in a projector, then why are they in there? When I turn off my projector (and the previous one) the fan runs for a few minutes. It is true that the bulb is the hottest part, and once the power is gone, the bulb will not get any hotter, but what about the rest of the projector? That is why the fans run after the projector is "off" - to cool rest of the projector parts - electronics and optics tend not to like being cooked.

It's not that fans are not necessary in a projector. It's whether they are necessary to run when the lamp shuts off. Maybe the termperature tolerance of the PJ cannot tolerate heat from *everytime* the PJ is turned off but maybe it can accomodate the very occasional power outage while the PJ is running. Maybe they leave the fan run until the thermostat shuts it off for a reason, or maybe not.

The conventional wisdom is that the UPS running the fan is to protect the bulb/lamp. But I agree with stereodude and usualsuspects that that doesn't seem right since the lamp can't get any hotter when it is the hottest thing already when the power is cut.

So the real question is whether other parts of the projector get too hot with no fan if the power is cut and whether that happening even the vey occasional time that a power outage would occur during PJ use would be harmful to the projector. That could be a good reason. I don't know.

It is interesting that projector companies know that power outages are a fact of life and they don't seem to (as far as I know) specify UPSs or show other concerns about this issue. (Maybe they do? could someone post that info?) And because they offer warranties, they would have an incentive to protect their equipment and require that proper installation require a UPS.

Has anyone heard of many, or even any, accounts of projectors breaking b/c their power was cut and the fan couldn't cool the non-lamp parts of the projector?

Also some people have the opinion that UPSs have "noisy" or otherwise bad power output.

See: http://www.avsforum.com/avs-vb/showthread.php?p=9815135#post9815135

I have discussed this matter of the fans running after power down in lamp based sets with engineers at many manufacturers and with engineers from the lamp OEMs. The TV makers generally way not to worry about ocassional outages, but that for safety and reliability it is best to let the lamp fans run at power down, ie don't remotely switch the power off routinely. This is exactly the company line that would be expected. Off the record, most acknowledge that it is unlikely that damage to lamps from a lack of cooling fan after shutdown is anywhere near the significance of start cycles. The primary reason for the fans is to cool the system to allow a faster restart, as nearly every unit will not allow a hot strike, which could damage a lamp. The only potential problem with not cooling a lamp after shutdown is the potential for "thermal lag" in the few milliseconds after the power is removed. Since cooling systems are indirect, it is unlikely that this is a factor with the remote possibility of very compact projectors. Far more important than occassional shutdown without a fan is the number of start cycles and overall cooling.

As for UPS or no UPS on projection systems...

It's your projector and it's your investment.

Stereodude's argument of the owner's manual?? The owner's manual rarely includes integration instruction.

Even though the projector manufacturers created specialized units for home theater now, their primary market is still commercial and education...

If one manufacturer were to recommend a UPS while others left their manuals as they are, it may appear to the layman (or the trustees who vote on these bids) that certain products were uncompetitive and therefore be excluded from their fair share of consideration for those proposals...

Placing a UPS ahead of a projector is considered a best practice by the integration community. Primarily because their clientele are NOT enthusiast tinkerers like some of the people reading this right now.

The projects need to be as reliable and self correcting as possible, because your attorney, your kids doctor, or your accountant also love HT, but unlike you guys, they aren't really getting manuals out and climbing ladders...

Placing a UPS removes, or at least minimizes the chance, for another possible failure point... In practice, adding a UPS (along w. a decent surge protector) allows the bulbs to actually live their intended service life, vs. the inevitable service calls we get from big box clients who want someone to look at their sets after electrical storms and power outages.

So, would it be OK to plu the UPS to the powerstrip? Like this:
Projector->UPS->Powerstrip

I can't put the UPS after the PowerStrip, because then the UPS would be handling way too much load. I only want the PJ to load the UPS.

I'm all in favor of debunking conventional wisdom and would love a chance to not spend money on something that wasn't necessary, but I did find this tidbit from HP:

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00277925&lc=en&cc=us&dlc=en&product=464552


"Other precautions that may extend the lamp life
Listed below are more ways to extend the life of the lamp.

When the projector is turned off, the fans will continue to run for a while to cool the lamp. Do not disconnect the power cable from the projector until the fans turn off.

. . .

In some countries/regions, the line voltage is NOT stable. This projector is designed to operate safely within a voltage range between 100 to 240 volts AC, but could fail if power surges of ±10 volts or brownouts occur. In areas where the voltage may fluctuate or there are frequent lightening storms, it is recommended that you connect your projector through a power stabilizer, surge protector, or uninterruptible power supply (UPS)."

I would have found this more persuasive if they had said "to cool the projector" or the "projector components" instead of the "lamp" which we know from basic physics would not need additional cooling after its power source has been cut.


On the other hand Sony says:

"Can a UPS, Power Generator, or Power Inverter be used with my Sony® product?


The UPS, power generator, or power inverter must meet the voltage and current requirements of your device. It is preferred and recommended for the power to be a pure sine wave. UPS, power generator, and power Inverter design varies greatly and undesired operation or damage may result from units that utilize a 'modified sine wave'. Because of this we cannot make any recommendation on their use."

http://www.iq.sony.com/SRVS/CGI-BIN/WEBCGI.EXE/,/?St=781,E=0000000000726748950,K=4061,Sxi=6,Case=obj(87048),V ARSET_OBJ=87048,VARSET_TSRC=results,UseTemplate=case.tem,VAR SET_TOP=TRUE


most UPSs output a modified sinewave during power outages, and some of them output modified sinewave all the time: see: http://www.carebase.com/WP-Standby-UPS-Uninterruptible-Power-System-Merits.htm


"Using a modified sinewave UPS is generally not a problem for low end equipment as most switch mode power supplies like the ones found in your PC don't mind the square wave, even though they were designed to run on a pure sinewave. Problems start however when you start using them with more sensitive equipement. Anything with a transformer in it won't work to start with. Higher end systems may dislike the power supply and function (or disfunction) accordingly." see: http://www.alphaenergy.com.au/index.php?action=help&helpcatID=159&helpID=3063

I know the projector, equipment and subwoofers need to be on the same phase to eliminate ground loops,

Thanks!

Dave

This is also AVS fokelore. Ground loops have nothing to do with which phase you are on.

Professional broadcast, video mastering, and audio facilities for the most part have three phase power like the rest of the Earth's commercial buildings. How do you think they avoid ground loops? It's done by proper systems engineering in the area of grounding.

Air temperature in the projector will rise, but the bulb temperature will not. The hottest item in the projector will not get hotter without any additional input power.

Look, since the very first portable projectors in the 1940s, fans have been designed to run for a period after the lamp is turned off. The commen stated reason is to cool the bulb slowly. Remember slide projectors? Why must people argue long standing scientific practice backed by real world evidence.

A UPS on a projector is yet another ounce of protection in the chain. There are no ill effects as long as the UPS is sized for the projector load. Even the fact that cheap UPS units produce dirty power on battery. So what - you need clean sine wave power to run a fan for five minutes?

Look, since the very first portable projectors in the 1940s, fans have been designed to run for a period after the lamp is turned off. The commen stated reason is to cool the bulb slowly. Remember slide projectors? Why must people argue long standing scientific practice backed by real world evidence.

A UPS on a projector is yet another ounce of protection in the chain. There are no ill effects as long as the UPS is sized for the projector load. Even the fact that cheap UPS units produce dirty power on battery. So what - you need clean sine wave power to run a fan for five minutes?

Real world evidence to me would consistent of actual reports (even anecdotally) of projector failure from excess heat after a power outage. Educated doctors bled people for hundreds of years thinking that it was helpful. We occasionally are wrong in our conventional wisdom.

As lcaillo's OEMs say, the running of the fan after shutdown is so that the units can be started again more quickly when cooler since they cannot be started when hot. That would be especially important for the fourth grade slideprojector so that it could cool down in order to be turned on again for the next class.


(And if you wanted the bulb to cool *slowly*, you should NOT use a fan. If you want to bulb to cool *quickly* you would use a fan.)

In any case, the bulb, the hottest thing in the PJ, is NOT going to get hotter when the power is cut.

Consider dQ/dt = k(dT); where dQ/dt is the rate of heat transfer over time, k is a constant that depends on the physical characteristics of the medium (components in the projector), and dT = T0 - T1, the temperature differential between the lamp (T0) and another component (such as the air) in the PJ (T1).

T0 > T1; i.e., the lamp is hotter than other components in the PJ.
So now you cut the power to the lamp. But T0 > T1 still; so there is a movement of heat Q over time towards the other components where the temperature (T1) is lower. And that brings up T1 as the heat settles into the other parts of the PJ, including the surrounding air.

Meanwhile, T0 *must cool down* because dQ/dt is carrying away that heat to the other parts (including the air) in the PJ. Eventually T0 = T1 and no more heat is flowing. T1 stops rising and both temperatures begin to cool as heat is lost (as it was all along also) to T3 (the areas outside the PJ).

(by the way, this also explains why the inner portions (T1) of your turkey continue to get hotter AFTER you take it out of the oven and it is resting waiting to be carved as it absorbs heat from the outer portions(T0))

Other NON-LAMP components in the PJ will get hotter when the power is cut and no fan is running. But I still don't see any reason to believe that that temperature increase to non lamp components would be large (it would be distributed over many many things) or worth worrying about. It could be, but I haven't seen anything persuasive to show that it is.

When the arguments are:
1) We've thought this way for years; and your fourth grade slide projector and current fans continue to run and that means the fan must run all the time; and assertions (by HP for instance) of the false proposition that the *lamp* will get *hotter* without the fan when the power is cut.

vs.

2) Sony says UPS power may be harmful and explicitly does NOT recommend a UPS; other manufacturers show no concern about the issue (and they would if they were faced with warranty claims for broken projectors from power cutoffs); OEMs say that the cooling fans are b/c the units cannot have a hot start and so must cool down quickly so that they can be started again; and most who seem to advocate using a UPS don't seem to understand that the hottest thing can't get hotter when the power source is cut (usualsuspects excepted)

I'm more persuaded by 2) at the moment, but I'd still be interested in additional real facts, evidence and good reasoning on the topics of whether other NON-LAMP components would actually be harmed by the very occasional power outage (lcaillo OEM sources suggest no) and whether the PJ itself might be harmed by bad UPS power (Sony suggests yes) .

The concern for the rate of cooling is devitrification in the glass. The difference of running the fan or not is likely not going to make much difference in that rate as the cooling is indirect. The same applies to any potential thermal lag and the likelihood of the fan affecting that. The fan is not on the heat producing element itself, but provides airflow over the housing of the lamp. The bottom line is that it just isn't a big deal compared to start cycles, as it is unlikely to occur very many times over the life of a lamp anyway. If one has a repeated problem with outages, then it might make sense to consider a UPS or generation system with clean output.

I ran 3 circuits all GFCI'd as well. One for components, one for sub and one for projector.

As soon as the power is cut, the lamp will no longer be creating new heat. But at teh same time the air-flow will be cut.

I would say that the temperature will rise, especially at certain 'hotspots'. But unless this is frequent should not be an issue.

The issue would be if the power came back on and the projector was started again before the bulb had cooled. But as we know the projectors have protection against this happening.