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Author
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Topic: Lamp AC
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Jean-Michel Grin
Expert Film Handler
Posts: 222
From: Geneva & Lausanne, Switzerland
Registered: Jul 2002
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posted 07-19-2002 05:13 AM
Antonio,What kind of rectifier are you using in your cinema ?
Conventional like a IREM or an Electronic model ?
What is the wattage of your lamp ?
I've been experienced the same problem with a 7000 watts Osram Lamp and a IREM Variable Plunger (I'm not sure of the therm) rectifier. We wanted to replace the condensators at the output of the unit but, finaly we have exchanged this conventional IREM rectifier (is was too noisly) for a electronic ADDE BBR-180 rectifier and we got less trouble. Sorry I can't tell you nothing more... Good Luck !
Jean-Michel Grin - Europlex Cinemas (Switzerland)
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 07-19-2002 06:13 AM
Usually, it's the amount of CURRENT ripple that is measured. Excessive current ripple causes flicker in the light output, and quickly erodes/damages the lamp electrodes. In countries with 60Hz electrical power, the 60Hz ripple "beats" with the 48 cycle (2-blade shutter) or 72 cycle (3-blade shutter) frequency to produce a very noticeable and annoying 12Hz. flicker.------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 07-19-2002 12:36 PM
Some links to information about excessive current ripple:
http://www.xenonbulbs.com/pdf_manuals/xenon_bulb_info/xenon_bulb_failure_analysis.pdf
http://www.ltilamps.com/techinfo/arc_instab.html The Osram publication "XBO Theatre Lamps" says: "A better method is to estimate the ripple by means of the light. Using a fast enough photocell and an oscilloscope, it is possible to ascertain whether the ripple is in the correct order of magnitude by MEASURING THE LIGHT, without using a great deal of equipment. With a ripple of between 5 and 10% the light ripple is about 50% higher, as the luminous flux is proportional to the lamp current to the power of 1.5." In other words, let a bit of the direct light from the lamphouse (no shutter moving) shine on a properly loaded silicon photocell connected to an oscilloscope. Look at the "steady state" light output and the amount of light ripple using the scope. ------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
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