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Author Topic: Commenting on: Irem Rectifiers Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-04-2007 06:21 PM                     Which is within spec. The N3-100 is rated at less than 8%. To get it below 3% you need the "AFU" which is standard on the N3-150 and above.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 04-06-2007 08:38 AM                       quote: Demetris Thoupis perhaps the conversion from 230 to 110 might have something to do about it. As far as I am concerned, Irem makes damn fine rectifiers. Demetris, with the exception of some very small power supplies that are/were made for that voltage, we don't operate motion picture rectifiers at 110V in this country. We just don't use 220/208V in our homes (except for major appliances like electric ranges and clothes dryers).  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 04-06-2007 09:43 AM                     So what do you run them on? 240V single phase? 240V three phase delta? 480/277V or 208/120V wye system? I doubt that 600/347V would be used, at least in the US, where it only seems to be for heavy industry. What about in Canada? Does it vary from place to place? If so, do you have to order different equipment for each system, or do you have multiple tappings? I've seen quad-Voltage ballasts, 120/208/240/277, for metal halide floodlamps. I never fail to be confused by the range of Voltages and systems that you have over there. Most traditional rectifiers here run on 415V three phase, though some of the smallest ones are 240V single phase. Both are quite common for switching supplies. Strictly speaking I should call it 230/400V now (European harmonisation thing) but nothing has really changed, and old habits dye hard.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-06-2007 10:52 AM                     The norm in canada is large industrial devices are usually 3 phase 208volt phase to phase 115 to neutral consumer home wireing is 120 volt single phase to neutral and 240 between the two high legs Larger systems are nominaly reffered to as 600volt but 550 is the normal measured amount  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 04-06-2007 11:05 AM                     So what would you normally run a 15kW Imax on in Canada? In industrial terms that's still a pretty small load, Would it be 208V three phase wye?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-07-2007 11:38 AM                     The miller powersupplies are 208 3 phase many older theatres used 550v 3phase recifiers as that was the only 3 phase in the building for the air handles and older MG sets  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-07-2007 12:26 PM                     Many commercial buildings in the USA have both 480 3-phase (277 per leg) and 208 3-phase (120 per leg) available. If the supply can handle the higher voltage, there is no reason to use the lower voltage since it will increase the current needed and wire size. It would make sense to me to use 480 for a 15KW system. Due to the high currents involved, we normally over-spec the wire and breakers that feed the rectifier...that cuts down on failures (burned wires and failed breakers) considerably.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-07-2007 03:58 PM                     So far the best set up I've seen is the Iwerks(Designed by our own Phil Hill) rectifier setup that is made from paralleling three 7kw Strong Switchers. This setup runs on 208 three phase and with the high efficiency of the rectifiers the current draw is much less than the typical Miller unit that Imax is using. This would be the equivelent current draw of running an Iron core rectifier on 480 three phase. These three switching rectifiers are all well balanced sharing the load equally and they are current monitered by the Allen Bradley projector computer. Running this way each switcher is basically coasting operating a 15kw lamp. I have yet to hear of a single rectifier failure. Lamp life is excellent going past the warranty with all types of lamps by an easy 20% to about 1200 or more hours on a 15kw lamp. I don't know of any LF booths that push the large lamps more than about 20% or so, many feel that it gets pretty risky after that. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-07-2007 07:20 PM                     Most large format operate the 15K to 1200 hrs rectifier issues have never been a big issue with lamplife but the divitrification of the quartz wall  |  IP: Logged

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