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Author Topic: ORCON Ammeter question Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 08-26-2003 08:52 AM                        We are using older ORCON lamphouses, model XH4500 (or something close to that) with 4500w bulbs. They are powered by the old transformer rectifiers (non-switching type) with the big wheel on top to adjust the amperage (see pictures of it in the Movies in the Park in the Pictures section of the FTForum). When I set it up a few years ago, I set the voltage to the OSRAM spec sheet for the bulb (possibly 45-50v, not sure, but it was to what the manufacture spec-ed). Then I set "The Wheel" to bring the amperage up to spec also. Problem is, the ammeter on the ORCON only goes up to 120a, whereas the bulb required something like 140 or 150 amps. I tried reading the amperage using one of those clamp meters but couldn't get a good reading so what I did was, I calculated how many turns the adjustment wheel took to make an increase of 5 amps and then just kept turning the extra turns to bring it up past 120 to where my calculations would make it reach the amperage that the bulb required. This brought the meter up to the area above 120 and before it "pinned" against the edge of the meter. Thing is, this has begun to irk me to no end because I know this is not an accurate way to set this thing, although the bulbs seem to be doing just fine....very steady burns, no wandering arc or flicker, no darkening and no bubbles. Why would the meters be calibrated to only read 120 amps when the lamphouse is designed for 4500w bulbs? Or have the bulbs specs changed radically since the lamphouse was designed? And please excuse my vague-ary about the numbers. And while I'm asking about the Orcon, does anyone know how to set the hours meter back to zero on these things? We just added an additional exhaust fan on the stack that we got from Granger as the ambient temp in the non-air conditioned, out-in-the-sun-all-day booth can easily reach 90 degrees. Frank PS -- The ORCON -- it's a light sieve -- it leaks light from every joint. By the time I am done wrapping all the cracks with aluminum foil, the think looks like a huge Thanksgiving turkey ready for the oven.  |  IP: Logged Ken Layton Phenomenal Film Handler Posts: 1452 From: Olympia, Wash. USA Registered: Sep 1999 posted 08-26-2003 09:01 AM                     I believe that is actually only a 4,000 watt lamphouse. ORC lamphouses were rated lower than the model number. Example: the old M-1000 lamphouses is really a 700 watt unit.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 08-26-2003 11:51 AM                       quote: And while I'm asking about the Orcon, does anyone know how to set the hours meter back to zero on these things? Install a new hourmeter. Resettable lamphouse hour meters are a recent thing. It's not really a good idea, because by zeroing it out, you lose your lamphouse history. I've always thought there should be two hourmeters: one for the lamphouse, and a resettable one for the bulb hours.  |  IP: Logged Rick Long Jr Expert Film Handler Posts: 211 From: Toronto, Canada Registered: Jul 2000 posted 08-26-2003 09:04 PM                     Chances are you're going to be close with the current, but I would want to verify it. Make sure the clamp meter you're using is able to read DC amps. Some lamps had adjustable shunts for the ammeter, though I don't recall seeing them in ORC lamps. Kneisley maybe? BTW, Xebex lamps used to have both a resettable and a life hour meter.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-26-2003 09:14 PM                     Most ORC's had a calibratable shunt  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 08-26-2003 09:45 PM                     I simply dismantled the meters to "zero" them. It is a big pain in the rear, but it can be done. Ken is correct about the ORC bulbs. Gordon is also correcrt about the meter shunts. However, do not attempt to calibrate them unless you have something that will measure the current correctly. I have seen some of those damned things as much as 15 amps out of calibration. [ 08-26-2003, 11:38 PM: Message edited by: Paul G. Thompson ]  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 08-27-2003 02:50 AM                        Thanks guys. I am going to get a good working DC ammeter and see where I am. Even if the lamphouse is rated for 4000W, there doesn't see to be any dire consequences so far. In fact it seems to be humming along just fine. I will check to see if anything looks amiss inside. But so far, so good....unless of course I find that everything is slowly charring away into brittle lumps of carbon inside. Hell with taking the hour meter apart -- it's much easier just keeping a good record in the cardholder on the back of the unit. Frank  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 08-27-2003 04:27 PM                     Frank, just an ammeter might not do the job. Be sure to get the shunt with it. You might be better off with the meter you have. Use a ammeter clamp or something that is accurate so you can adjust the shunt properly.  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 08-27-2003 06:15 PM                     You might consider hooking up and looking at it with an ocilliscope. Even though the installed shunt might be off, excessive ripple will tell you something's wrong.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 08-27-2003 08:57 PM                     I sold the same lamphouse set to Gusman Theater, the site of the Miami Film Festival almost 20 years ago. This unit is basically set up for 4 kw operation. You could have a tech swap out the meter / shunt to one that goes to 200 ampere. The Orcon shunt has an adjustment slot to calibrate the meter to spec but a change out to higher amperage would make life more simple....but think of the "job security" while you twist the knob on the rectifiers  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 08-27-2003 09:13 PM                  Frank, make sure the "clamp-on" meter is for DC too. Most are only for AC. >>> Phil  |  IP: Logged Sam Hunter Jedi Master Film Handler Posts: 779 From: West Monroe, LA, USA Registered: Jan 2002 posted 08-28-2003 09:32 PM                     Speaking of CLAMP ON AMP METERS just how does that thing work?  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 08-28-2003 11:45 PM                     Electro-magnetic fields. Just clomp it around the cable and it will read the current. They are quite accurate. Naturally, the higher the cost of the unit, the more accurate of a reading you would expect.  |  IP: Logged Sam Hunter Jedi Master Film Handler Posts: 779 From: West Monroe, LA, USA Registered: Jan 2002 posted 08-29-2003 12:47 PM                     I understand how ac clamp on amp meters work and know they rely on the changing magnetic field to induce voltage in the clamp loop like a transformer but dc does not change so there is only one magnetic field and it does not reverse polarity. So my question is again, exactly what method do DC CLAMP ON AMP METERS use?  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 08-29-2003 12:53 PM                       There's still a magnetic field that surrounds each conductor and is proportionate to the amount of current flowing through it, it's just not changing direction.  |  IP: Logged

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