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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Fri Nov 30, 2012 12:10 am Post subject: CRT Power Consumption |
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I have just introduced a UPS into my projector setup. I only have the projector connected to the UPS. The UPS is rated at 1KVA. When I turn on the projector the LEDs indicate a load of about 1/3 capacity which I was expecting. I then sat down and watched a movie after which I noticed power consumption had climbed to about 85% of the UPS capacity. When I stopped playing the movie power consumption dropped to about 1/3 capacity again. I wasn't expecting such a large power increase when playing a movie.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Fri Nov 30, 2012 12:31 am Post subject: |
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So, about 165w at idle, and 425w playing a movie... Sounds like the right ballpark to me.
Just like an audio amplifier, the projector doesn't draw much current until it's doing something. The video amps don't draw much during low-APL scenes, and really ramp up during high-APL scenes. Project a 100IRE signal, crank the gain on all three tubes to max, max out the contrast, and the projector will probably draw something close to whatever is on the badge on the case.
SC
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Fri Nov 30, 2012 12:35 am Post subject: |
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I asked about this 3-4 years ago and was told the consumption was the same. But it would be unusual for that to be the case (I didn't accept the answer then) as the peak white is around the maximum capacity of the power supply. If you present (from the source) an almost black field it would be far from peak, and as such near minimal consumption, no?
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Trust no one. Absolutely no one. Advice of the board.
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Fri Nov 30, 2012 6:35 am Post subject: |
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Right. That's why you can't get a full-white screen as bright as a small white area -- there just isn't enough current to throw that many electrons at the phosphor. With a small white area you can use the full capacity of the power supply in that smaller area, so it's brighter.
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Fri Nov 30, 2012 7:27 am Post subject: |
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Unless you know the power factor of the projector you really need to work in VA and not watts. I dont know if the projector has power factor correction in it or not, but id expect itll be lagging, so youll need to find out the maximum current drawn then multiply that by the voltage ( 230 volts is nominal in Australia ) which will give you consumption in VA.
A 1kVA UPS should be able to deliver around 4.3 amps, and the amount it can deliver should be written near the outputs on the UPS. What does the rating say on the projector?
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Fri Nov 30, 2012 9:52 am Post subject: |
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| garyfritz wrote: | | Right. That's why you can't get a full-white screen as bright as a small white area -- there just isn't enough current to throw that many electrons at the phosphor. With a small white area you can use the full capacity of the power supply in that smaller area, so it's brighter. |
I also wondered about this, but then figured out this is not the case. This phenomenon is caused by the Automatic Beam Limiting (ABL) because when an electron hitting the CRT's faceplate x-rays generated, more high speed electrons generate more x-rays, and the machines must comply to national emission standards, so they have to limit the maximal amount of generated x-rays. If the power supply itself is the sinner, then why didn't they do a bigger capacity PSU? All, I mean ALL CRT pj model suffers from this.
Back to the thread: I measured my PG xtra's power consumption with a single current meter, then multiplied by the actual mains voltage and found that with a full black screen it consumed about 300VA with a full white it gone up to 380~400VA, the official rating is 550W, this machine has power factor compensation so I think my measurements were accurate. While the power consumption of a CRT is depending on content, but not too much, the biggest consumers in the projector are the deflection coils and convergence/focus coils (and their driver stage) which are always in order regardless of screen program.
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projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Fri Nov 30, 2012 4:41 pm Post subject: |
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| gjaky wrote: | | I also wondered about this, but then figured out this is not the case. This phenomenon is caused by the Automatic Beam Limiting (ABL) because when an electron hitting the CRT's faceplate x-rays generated, more high speed electrons generate more x-rays, and the machines must comply to national emission standards, so they have to limit the maximal amount of generated x-rays. |
But they don't prevent high-intensity white, which is what would generate the x-rays, if any. You can get intense enough to burn the phosphor if it's a small area. The limit is not on intensity, but overall light emission == overall current.
| Quote: | | If the power supply itself is the sinner, then why didn't they do a bigger capacity PSU? All, I mean ALL CRT pj model suffers from this. |
My guess: economics. They size the PSU so it works for "normal" use. Ice Age movies are apparently not considered "normal" use.  It would probably cost a lot more to use a much bigger PSU, and it would only make a difference in snow scenes.
Curt? Mac? Somebody who actually knows what they're talking about back me up on this?
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Fri Nov 30, 2012 10:42 pm Post subject: |
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| garyfritz wrote: | | gjaky wrote: | | I also wondered about this, but then figured out this is not the case. This phenomenon is caused by the Automatic Beam Limiting (ABL) because when an electron hitting the CRT's faceplate x-rays generated, more high speed electrons generate more x-rays, and the machines must comply to national emission standards, so they have to limit the maximal amount of generated x-rays. |
But they don't prevent high-intensity white, which is what would generate the x-rays, if any. You can get intense enough to burn the phosphor if it's a small area. The limit is not on intensity, but overall light emission == overall current.
| Quote: | | If the power supply itself is the sinner, then why didn't they do a bigger capacity PSU? All, I mean ALL CRT pj model suffers from this. |
My guess: economics. They size the PSU so it works for "normal" use. Ice Age movies are apparently not considered "normal" use. It would probably cost a lot more to use a much bigger PSU, and it would only make a difference in snow scenes.
Curt? Mac? Somebody who actually knows what they're talking about back me up on this? |
Number of Electrons are directly proportional to the current, so the curent what is needed to be limited. In the NEC PG xtra's HVPS there is a pot for setting the beam limiting circuit, and it is firmly sealed by the factory, also there are special notes in the service manual for how crucial to set the proper beam limiting level. In a NEC the HVPS consist of a driver board and two "normal looking" flyback transformers paralleled, I don't think adding a third flyback transformer and a stronger driver board would have greatly raise the production costs of the unit. Also in their age these projectors were intended for data projection use, where mostly white background is projected (at the highest possible brightness), so from manufacturer side the strogest HVPS wolud be desirable.
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projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Fri Nov 30, 2012 11:49 pm Post subject: |
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This discussion could become very elaborate and I'm not sure the interest is there anymore. But as far as the Xray issue, there is lead mixed in the glass to help block xray emission but in higher light output tubes it still had difficulty so this is why your not suppose to run them without the lens on, hence having the lens protect circuit. They may have put some lead in the lens elements also but I have not read anything to prove that. But it would have to meet requirements with the lens on even if it didn't meet them with the lens off.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Sat Dec 01, 2012 12:35 am Post subject: |
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| CasetheCorvetteman wrote: | Unless you know the power factor of the projector you really need to work in VA and not watts. I dont know if the projector has power factor correction in it or not, but id expect itll be lagging, so youll need to find out the maximum current drawn then multiply that by the voltage ( 230 volts is nominal in Australia ) which will give you consumption in VA.
A 1kVA UPS should be able to deliver around 4.3 amps, and the amount it can deliver should be written near the outputs on the UPS. What does the rating say on the projector? |
Looks to be 700w at 4.6amps.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sat Dec 01, 2012 12:44 am Post subject: |
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| km987654 wrote: | | CasetheCorvetteman wrote: | Unless you know the power factor of the projector you really need to work in VA and not watts. I dont know if the projector has power factor correction in it or not, but id expect itll be lagging, so youll need to find out the maximum current drawn then multiply that by the voltage ( 230 volts is nominal in Australia ) which will give you consumption in VA.
A 1kVA UPS should be able to deliver around 4.3 amps, and the amount it can deliver should be written near the outputs on the UPS. What does the rating say on the projector? |
Looks to be 700w at 4.6amps. |
Those numbers don't calculate properly. Is you voltage 230?
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sat Dec 01, 2012 3:41 am Post subject: |
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Mac, nominal voltage here in Australia is 230v yes, not 240v as is quite often thought. Id say those numbers listed are assuming a leading or lagging AC load.
KM987654, ignore the wattage listed, it means 18 kinds of f### all since the manufacturer has no idea on the power factor of the AC load youre connecting. It may be some sort of indication of the power factor handling capacity of the device, but you dont need to worry about it, its VA youre interested in, and youve got 1000 of them, regardless of power factor.
1kVA is equal to 1000 watts ( or 1kW ) at unity power factor. 1kVA = 700 watts at .7 power factor. Its still 230v and 4.3A, be it leading ( capacitive load ) or lagging ( inductive load ), less work is being done for the same power consumption, and to avoid all that, its easy to use VA.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Sat Dec 01, 2012 3:58 am Post subject: |
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| macgyver655 wrote: | | km987654 wrote: | | CasetheCorvetteman wrote: | Unless you know the power factor of the projector you really need to work in VA and not watts. I dont know if the projector has power factor correction in it or not, but id expect itll be lagging, so youll need to find out the maximum current drawn then multiply that by the voltage ( 230 volts is nominal in Australia ) which will give you consumption in VA.
A 1kVA UPS should be able to deliver around 4.3 amps, and the amount it can deliver should be written near the outputs on the UPS. What does the rating say on the projector? |
Looks to be 700w at 4.6amps. |
Those numbers don't calculate properly. Is you voltage 230? |
Sorry. Yes 230v.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sat Dec 01, 2012 2:28 pm Post subject: |
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At 230v and if you are actually drawing 4.6 amps that comes to 1058 watts. And you should add at least 20% for PFC which would be another 212 for a total of 1270. So your UPS is not large enough. It may work but not well. Or you may not be drawing that many amps. But that's where if should be.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Sat Dec 01, 2012 10:24 pm Post subject: |
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| macgyver655 wrote: | | At 230v and if you are actually drawing 4.6 amps that comes to 1058 watts. And you should add at least 20% for PFC which would be another 212 for a total of 1270. So your UPS is not large enough. It may work but not well. Or you may not be drawing that many amps. But that's where if should be. |
It's not maxed out so not drawing 4.6amps but I only have the projector hooked to it
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sat Dec 01, 2012 10:57 pm Post subject: |
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| km987654 wrote: | | macgyver655 wrote: | | At 230v and if you are actually drawing 4.6 amps that comes to 1058 watts. And you should add at least 20% for PFC which would be another 212 for a total of 1270. So your UPS is not large enough. It may work but not well. Or you may not be drawing that many amps. But that's where if should be. |
It's not maxed out so not drawing 4.6amps but I only have the projector hooked to it |
That's good. So it should be fine.
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sun Dec 02, 2012 3:22 am Post subject: |
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Have you got a tong tester there KM? Thats the best way to see exactly what current its drawing.
Is that 4.6A on the nameplate of the projector or the UPS?
230v X 4.6A = 1058VA, no need to add PFC to that.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Sun Dec 02, 2012 8:12 am Post subject: |
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| CasetheCorvetteman wrote: | Have you got a tong tester there KM? Thats the best way to see exactly what current its drawing.
Is that 4.6A on the nameplate of the projector or the UPS?
230v X 4.6A = 1058VA, no need to add PFC to that. |
That's the output rating on the UPS.
You know I was just knocked over by the difference in power consumption between just running the projector and playing a movie. I run server equipment on UPS all the time and there is little difference in power consumption when a server is just running and users are accessing it. It's a lot different with a CRT projector. I thought people here would find that interesting.
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CasetheCorvetteman
Joined: 09 Nov 2008
Posts: 6326
Location: Australia
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| Posted: Sun Dec 02, 2012 8:28 am Post subject: |
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Yeah its an interesting thing, and its a whole lot more complex than people would believe when it comes to power consumption on AC devices, straight up resistive loads and power factor corrected loads are pretty simple, but when loads get capacitive or inductive, there is a waste of power that comes into it ( which is VAR, or volt amps reactive )
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Thu Dec 06, 2012 8:39 am Post subject: |
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With the above in mind I kept watch on the UPS while watching a movie and there is at least a 20% differential in power consumption between dark and light scenes with the latter consuming more power. I mean its really dynamic. This is crap isn't it I shouldn't be this interested in this.
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