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Author Topic: Deviation in rectifier output current Marin Zorica Jedi Master Film Handler Posts: 671 From: Biograd na Moru, Croatia Registered: May 2003 posted 04-16-2007 03:17 PM                     I have XBO2500 running @85A, but problem is that sometimes when I start lamp current goes up to 100A, then durring show falls to about 85A! Problem is that when i start lamp current goes up to 90A and after 20 minutes it falls to 70A......and problem is because rectifier have 6 step regulation...so during show I can't regulate current... Lamp is new and is same with other lamp.....maybe problem is in rectifier when transformer and diodes get's warmed!! I'm thinking about replacing diodes with stronger and put better cooling to system, opinion? Rectifier is three-phase built by one tech company 25-30 year ago.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 04-16-2007 03:24 PM                        Is this with all bulbs? I think this is a factor with bulb heating up the gas and pressure building. Have seen this on almost all systems; amps drop after heating. Louis  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-16-2007 05:51 PM                     On Christie/Ushio lamps this phenomon is so neglagable as to be non existant, a few amps drift at best. Have seen it alot on both Osram and LTI. To be safe and not sorry... also check all the large DC connections and the AC connections to the rectifier, especially those that are crimped. Check all bulb connections as well. Mark  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 04-16-2007 06:40 PM                     (like the olden days of carbon arc - the new rods would send the ampmeter up about 10 to 20 amps higher until the positive rod began to develop the crater, then settle down for the duration of the rod..)  |  IP: Logged System Notices Forum Watchdog / Soup Nazi Posts: 215 Registered: Apr 2004 posted 06-07-2010 03:18 PM                 It has been 1147 days since the last post.  |  IP: Logged Marin Zorica Jedi Master Film Handler Posts: 671 From: Biograd na Moru, Croatia Registered: May 2003 posted 06-07-2010 03:18 PM                     To get this mine old post to life.....I did think today about this problem....having two Osram 2500W lamp, one is powered via Irem N3 and other via some older rectifier, on Irem is all okay, but on other after 15min current drops from about 85A to 75A or so.... Dunno why, some says is because of lamp, but if is lamp it would be same on Irem? I was think, is it maybe because of older diodes and that they get warm and voltage drop across them get's higher, which results in lower current?  |  IP: Logged

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