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Author
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Topic: Bulb Current
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Pat Moore
Master Film Handler
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Posts: 363
Registered: Mar 2000
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posted 09-26-2000 07:25 AM
Randy has a good point; use the amperage you need to achieve proper illumination on screen. The problem is to determine that illumination level -- most booths and operators are not equipped with spot meters. We're also usually in a position where the correct light level was just about everything you could get out of the system.If the theatre was done right in the first place, there's a little "head room" that allows for some natural degradation in the system -- new bulbs are brighter than old bulbs, screens get a little dusty and less reflective, etc. I always followed the policy of running a lamp around 80-85% of it's maximum value when new. That allows the current to be increased through the life of the lamp to maintain somewhere near constant illumination. Lamp manufacturers do different things in rating their lamps. Some give a current range: maybe a 4kw runs from 135-150. Others used to give a "nominal" value, with a plus/minus range; i.e. maybe a 4kw would be 140A +/- 10%.
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John Pytlak
Film God
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Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 09-26-2000 01:41 PM
Some of the xenon lamp manufacturers publish product listings of their lamps, that include the recommended operating current range. For example, here is an on-line listing for the Osram XBO 5000 W/H OFR lamp: http://ecom.sylvania.com/osicatalog/multiresult.asp?Item=69315 Clicking on the "Product Info Bulletin" shows all the technical data you need. If you can't find a listing, contact the lamp manufacturer for a data sheet for the lamps you use. Exceeding the maximum current greatly increases the risk of catastrophic explosion. Running below the minimum current shortens the life of the lamp (premature blackening), and can cause unstable operation and ignition difficulties. ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Eastman Kodak Company Research Labs, Building 69, Room 7419 Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com
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Steve Guttag
We forgot the crackers Gromit!!!
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Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 06-27-2002 06:48 PM
Maximum is just that MAXIMUM.If you verify that your current on a 3KW lamp is indeed over 110amps, you are playing with fire. Sure it is only 2% over but it is over none the less. Since you have a CC-40U, why not set the internal links to "LOW"...that SHOULD get you in range. Steve ------------------ "Old projectionists never die, they just changeover!"
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