Film-Tech Forum ARCHIVE: Help estimating 6KW lamphouse temperature increase rate figure

This is topic Help estimating 6KW lamphouse temperature increase rate figure in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Julio Roberto (Member # 4976) on 02-16-2009, 04:04 PM:

Could someone with experience or easy access to a 6KW lamphouse (i.e. as used in some DCI projectors) guess, or even better, measure with a thermometer, at what RATE the temperature increases? I am looking for the rate of change rather than the maximun temperature that can be reached.

I.e. I'd like to know how much a thermometer nearby i.e. the entrance of the integrator rod would change from the time the lamphouse is turned on until EXACTLY 2 minutes pass by.

I'll appreciate it if someone could take a good guess or actually measure it whenever convinient. Thanks!

[ 02-17-2009, 08:33 AM: Message edited by: Julio Roberto ]

Posted by Mark Gulbrandsen (Member # 72) on 02-18-2009, 06:51 PM:

Thats easy with a CP-2000 since there is a temperature sensor at the entrance of the integrator rod itself as well as ambient temperatire and many others. The closest one to me is 3 hours away and I'll be there doing service in about a week and a half. If no one has found out for you by then I'd be happy to give you the info. Its very common for integrators to run at 60C to 70c or even hotter!

Mark

Posted by Julio Roberto (Member # 4976) on 02-19-2009, 12:51 AM:

Thank you, Mark, I would really appreciate it! I don't have access to anyone running a 6Kw lamphouse, only 4Kw or 2.5Kw.

Trying to determine if some devices, like i.e. similar to the Dolby wheel, will survive living in there.

Just keep in mind that it's the rate of change I really need, something like say 7ºc increase per minute from the time the lamphouse is started until two or three minutes (or more if you suspect the rate varies substantially) pass by. It could be something like +7º/minute the first couple of minutes and then +5,+3,+2 until it pretty much stabilizes at the 60º or 70º you mention, i.e.

I would need to know the highest rate increase within a minute, which should normally occurr within the first couple of minutes after switched on, probably.

Posted by Mark Gulbrandsen (Member # 72) on 03-05-2009, 08:07 PM:

Julio, Here ya go....
Perhaps not exactly what you need since I didn't have access to this thread when I was at the theater and if not let me know how often to take the reading... ie: every 10 sec or every 5 sec for the first two min for better resolution. I can do another reading for you tommrrow if need be as I'm still at this site. I posted the max temp just for those that may be curious how hot the thingy in there gets. Hope this helps...

Mark

Lamp Power 5120 watts
Amperage 148
Voltage 34.6

Ambient projector temp 24C

Integrator temperature rise over 15 min time.

1 min 33C
2 min 38C
3 min 41C
5 min 45C
6 min 46C
7 min 46c
8 min 47c
9 min 48c
10 min 48c
11 min 49c
12 min 49c
13 min 49c
14 min 49c
15 min 50c MAX.

Posted by Julio Roberto (Member # 4976) on 03-06-2009, 08:14 AM:

Thank you so much, Mark.

The rate increase is a bit lower than I expected for such a large lamp. A nice design on Christie's part!

It's almost exactly within the expanding coefficient difference average wavelenght breakdown (different materials expand at different rate with heat) of most used materials for multilayer refraction-based bandpass filters.

So incidently, the Dolby filter should be ok with it by barely a couple of degrees, as the more layers the worse the expansion-contraction problem as the distance between the layers, down the microns, is critical for the performance of such filters.

As long as the fan doesn't fail, most filters should be OK (a few won't, as 9ºC increase in a minute is more than some can take w/o seriously degrading in the long term).

Also, I wonder if it gets much worse if driving the lamp "full on" (I'm I correct that lamp can actually be driven at full 6000w instead of the 5120w measured?), but should still be within 10%, I would guess.

Posted by Mark Gulbrandsen (Member # 72) on 03-06-2009, 12:40 PM:

Actually the 6000 watt lamp can be driven to 6600 wats!! Dolby claimed there are in excess of 50 layers deposited on the wheel. Of course these are on the molecular level... So the heat level may indeed be too high for it's long term survival especially since most lamps are driven pretty hard... 5500 watts and up ust to get inside the 3-D light level spec. Oh boy, I can't wait till we need to start stocking these wheels [Eek!]

.

Mark