This is topic Help! Rect-o-Lite 45T Carbon Arc Rectifier in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Josh Jones (Member # 447) on 06-15-2001, 09:50 PM:
I need a schematic or other info for this beast. It is 3 Phase and I want to convert it to single phase. the wiring is beginning to crumble.
It also has abspestos covered wire, but has been converted to sil-tubes(solid state)Josh
Posted by Paul G. Thompson (Member # 655) on 06-15-2001, 10:31 PM:
Josh, I don't think you can convert that thing to single phase without going through a tremendous expense. You have a boat anchor probably heavy enough to moor the USS Oriskany... 
Posted by John Walsh (Member # 168) on 06-15-2001, 11:27 PM:
Yes, Paul is correct. Among other things, the transformer would have to be changed While I guess it could be done, it would very expensive. There are converters that change single phase into 3-phase, but they are quite expensive also. It would be far cheaper to just buy a new rectifer.You would still have to look around a bit though for a suitable supply, because arc lamps usually run at a higher voltage than xenon. So, you can't just go buy any old rectifier; you need to be able to modify one to match the lamp.
Posted by Josh Jones (Member # 447) on 06-16-2001, 12:42 PM:
I got these with the peerless type E lamps from the Delchar theatre. I believe it is possible to just find where the 3 points of connection are. the 3 individual bobbins of the transformer are not magnetically coupled. Rather, they are stacked like a triangle. the cores of each transformer do not touch. I am trying to trace the line in and just parallel all the input windings and run it on 1 phase AC, 220VAC.Josh
Posted by Gordon McLeod (Member # 33) on 06-16-2001, 03:52 PM:
Not a good idea and actually rather unsafe since the transformer will not be balanced and the transformers will probably overheat.
It would be very unusual for there not to be some coupling in the transformers.
Also there output current is rated when into a 3phase bridge.
If the outputs were to be parrallelled some form of load shareing resistors would be needed
single phase rectifiers are a dime a dozen
Posted by Randy Stankey (Member # 64) on 06-16-2001, 05:28 PM:
I would also ask that because the 3 "stages" of the rectifier are designed to work at 120 deg difference in phase from each other you would probably have a terrible problem with ripple voltage, wouldn't you?Heck, with all the surplus arc lamps (Old Super Trouper spotlights and such) floating around backstage in old playhouses, you should be able to find something to make it work.
Posted by Paul G. Thompson (Member # 655) on 06-16-2001, 05:40 PM:
Josh, all of the above are correct. If you fiddle with it to try and make it work, you probably find you will have a situation where there is Minimum output with Maximum Smoke. 
Posted by Josh Jones (Member # 447) on 06-16-2001, 06:18 PM:
I dont have time to track down a new set of rectifiers though. well, ripple would be a bit of a problem, this beast has no other filtration than two current control inductors.Josh
Posted by Joe Ritter (Member # 804) on 06-16-2001, 06:19 PM:
Hi all,
I once got to work on a unit that was portable 35mm.Super Simplex witha Peerless lamp on the back. The "rectifier" was a common DC shop welder. Miller brand DC. I nefer got the chance to see how this thing would work but if it would burn welding rods how would it work on carbons?-----------Joe Ritter------
Posted by Paul G. Thompson (Member # 655) on 06-16-2001, 06:21 PM:
Joe, I could be wrong, but I think the operating voltage for a given current may not match what the typical carbon rod likes to see. In addition to that, you have to be careful not to exceed the "Duty Cycle" of the arc welder, if it did work.
Posted by Gordon McLeod (Member # 33) on 06-16-2001, 06:31 PM:
MOst of the continous duty arc welder do work as the voltage/current ratio was pretty close to that of the superex trim
The duty cycle is the criticle item
In fact Miller welders are still the base unit in most Imax Powersupplies
Josh you are playing with a dangerous situation. If you end up haveing a fire your insurance company defintely will not cover you.
You will definetly have problems with what you propose
Posted by Josh Jones (Member # 447) on 06-17-2001, 05:51 PM:
So where does one find a single phase rectifier? I have found a pair of strong utilities with single phase rectifiers, but the guy didnt want to sell them. which was ok, because I found these peerless type G's in Mayville
Posted by Larry Shaw (Member # 388) on 06-21-2001, 11:25 AM:
Wouldn't this be better discussed on some sort of proctology newsgroup? And how bright do they need it in there anyway?
Posted by Paul G. Thompson (Member # 655) on 06-21-2001, 12:31 PM:
Larry, he is just looking for a set rectifiers. There is absolutely nothing wrong with that. Perhaps it should have been in the Equipment Wanted Tread, but we all make mistakes.
I have made some posts in the "wrong house", too. Others have done the same. What happens is that after the post is made, a second thought might come to mind that maybe it should have been in a different tread. However, it is too late to do anything about it.
Been there more than once.
Posted by Joe Ritter (Member # 804) on 06-21-2001, 02:19 PM:
Adding to the contimuing saga of the lack of rectifiers. I was wondering if one rectifier can run two lamps or is one rectifier required for each lamp? Also has there been any more thought given to using an Arc-welder for the supply. They have a setting on most of them to adjust the current required. I am not an old pro on this stuff, but like to know what can be done (safely) to get the job done. I don`t plan on trying to rewind primary coils though.------Thanks------Joe Ritter----
Posted by Gordon McLeod (Member # 33) on 06-21-2001, 02:41 PM:
Yes some of the older low intesnsity system used a common rectifier or MG set and one had to "steal the Arc" from one machine to the other
As for welders as previously mentioned certain one if they have the correct duty cycle cn be used for carbon arc operation. Even certain Xenon systems run on them
Posted by Larry Shaw (Member # 388) on 06-21-2001, 02:51 PM:
Sorry, it was an attempt at humor......
Posted by Tom Hutchinson (Member # 876) on 06-21-2001, 03:08 PM:
Josh, the best rectifier for your application would be a Strong Utility 4 tube single phase. Failing that, Kneisley 4-tube single phase. The Kneisley rectifiers have a weak point in the tap switch; it often arcs and corrodes; other than that the rectifiers are OK.These rectifiers will draw about 9 amps at 240 volt. They are suitable for 40-45 amps, 6 and 7 trim.
There are unlimited amounts of these in theatre basements and behind screens; lots in Canada just north of you too.
Posted by Gordon McLeod (Member # 33) on 06-21-2001, 04:00 PM:
Larry your humour was not lost on me
Posted by Josh Jones (Member # 447) on 06-21-2001, 04:07 PM:
Yes, there may be bunches of them in canada, but try and get a pair across the border 
Josh
Posted by Gordon McLeod (Member # 33) on 06-21-2001, 05:16 PM:
Since they are originally manufactured in the US and are returning to the country of origin there is now duty
Also under NAFTA projector parts are duty free