Film-Tech Forum ARCHIVE: ORC Rectifier problem?

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Posted by Richard B. Perrine (Member # 409) on 08-18-2004, 01:32 PM:

Here's the info.....we have a ORC XPS-45S set up at 110amps for a 4K bulb... lamphouse is a Xenon 1 with the glass reflector and a different ignitor (type unkown)...formally from John Harvey's Cinerama set-up.
a while ago.....the amperage dropped to between 70-80 amps and we got a little flicker. It stricks OK and run OK otherwise.

The diodes have bee checked....and even changed them and put in a new set.....with no change. Checked and tightend loose connections.

What else could be wrong? the manual don't give me a clue.

Some of the bigger ORC's have extra "current limiting" circuit breakers on them ...butnot on this one.

Can you guy give me some help here?

RBPerrine@aol.com

Posted by Gordon McLeod (Member # 33) on 08-18-2004, 01:39 PM:

On the XPS45 rectifiers they often had a second set of contactors (open framed styled relays) that switched the input taps from hig during ignition to the level selected they may have gone south
measure the lotage phase to phase on the input to the diodes to see if one of the tranformers is not outputing correctly and then look for a corroded connection to it

Posted by Mark Gulbrandsen (Member # 72) on 08-18-2004, 02:11 PM:

I believe that these use alumnium windings on the main trannys. back in the Midwest I serviced several drive ins that had these and I had the alumnium wire disentegrate where its crimped to the copper wire connections. Check these crimps carefully and I think you'll find one open. I reccomend re-doing all the crimps but coat the wires first with non-oxidation grease. but even with the grease the windings will eventually open again. Seems to be more the dis-similar metals that cause it to disentegrate over time.

Mark @ CLACO

Posted by Gordon McLeod (Member # 33) on 08-18-2004, 02:36 PM:

The XPS45 was a all copper transformer unlike the earlier ones that Miller made for ORC
The XPS45 is the same as the CFS and the LPA recifier of the same size (also the same as the current Strong HiReactance one)

Posted by Mark Gulbrandsen (Member # 72) on 08-18-2004, 05:28 PM:

Yea, I guess that they learned the hard way with the alumnium stuff and everyting after that was copper. What is the model number of those that had the alumnium windings?

Mark

Posted by Aaron Sisemore (Member # 145) on 08-18-2004, 06:40 PM:

Check that you have the full voltage on all three phases of AC into the lamphouse. If you don't, check the breaker in the wall, it is likely faulty.

Also, isn't 110A a little low for a 4K? I have been running 4K and 4500s at 135-145A...

-Aaron

Posted by Nic Margherio (Member # 273) on 08-18-2004, 07:16 PM:

I have a similar problem with a 3kW (110 amp) ORC with variable tap transformers. I stepped up the "fine" taps by 5 amps (seems you might want to do this anyway) and the problem went away. I think there is a bad secondary winding in one of the transformers.

Posted by Gordon McLeod (Member # 33) on 08-19-2004, 05:53 PM:

Mark said "What is the model number of those that had the alumnium windings?" XPS30 and XPS40 come to mind

Posted by Michael Schaffer (Member # 1204) on 08-20-2004, 05:17 AM:

Did you measure the current going through the diodes with a clamp-on amperemeter?