Film-Tech Forum ARCHIVE: Rebuild IREM rectifier

This is topic Rebuild IREM rectifier in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011607

Posted by Sigurd Wik (Member # 6131) on 02-12-2014, 06:20 AM:

I have a couple of IREM EX-170GM/3-E with input volt range 360-460V. Do any of you know if it is possible to rebuild this to input volt range 230V? Hard to find info on this, so I suspect it is not possible.

Sigurd

Posted by Edgar Prass (Member # 7558) on 02-12-2014, 06:27 AM:

3-phase rectifier can't be rebuilt to single phase.

Posted by Jim Cassedy (Member # 4115) on 02-12-2014, 10:14 AM:

It is true, as Edgar says, that it's almost impossible to re-build a 3-hase
rectifer to work on single phase- - HOWEVER, there is a "work around":

I know of at least half-a-dozen old theaters that are running both Irem and Christie
3-Phase rectifiers on single phase by using a bank of large capactors to
create a "phantom" 3rd phase. I used to have a wiring diagram on how to do this,
but I can't seem to find it at the moment. You might be able to find info online
since trick also works with certain types of 3phase motors too.

You should be aware that:
1) This method is slightly electrically inefficent and so it will will "downsize"
your rectifer capacity, but I'm not sure by what percantage. So, You won't be able
to run a 4K bulb on a 4K rectifier. I think it cuts the rating by appx 25%, but
I couldn't swear to that in court.

2)The rectifers converted this way will often a make loud, very annoying, buzzing
sound at appx 120hz when you use this trick. I find the buzz so annoying that I
can't stand to be in the same room for more than a few minutes where one of
these 'converted' rectifiers is running.

But it doesn't seem to do the rectifer any harm- - One theater I know has been
running their capacitor-converted rectifier for over 25 years now, and has
never had any problems with it. Not even a burned out diode, since I think
they're running well below their rated current specs.

At the theaters I've seen this done at, the buzzing seems to be worse with Chrisite
rectifiers than with the IREM units.

I might be able to take a look at one of the rectifiers and make a wiring diagram
of how the conversion was done, but I'm tied up for the next two weeks in another
part of town doing some work for the Academy Awards, so it would have to wait.

Perhaps somone else on the forums has done this 'trick' and can give you info
on how to do it.

Posted by Sam D. Chavez (Member # 1841) on 02-12-2014, 10:44 AM:

I don't think single phase was mentioned. Perhaps he just wants to run on 220 3 Phase. Maybe I missed something?

Posted by Jim Cassedy (Member # 4115) on 02-12-2014, 11:01 AM:

D'oh! I think you're right, Sam.

I read & wrote that reply before I had my morning coffee so my mind
wasn't fully 'firing on all cylinders' yet & I misinterpreted the question.

"sometimes the mouse is quicker than the mind"

Posted by Sigurd Wik (Member # 6131) on 02-12-2014, 01:32 PM:

Thanks for quick replies. Yes, I just want to run 230V on three phase.

I'm in the process of changing lamphouses and rectifiers and I can have these for free, that is why I wonder if it is at all possible without installing a transformator, which would cost a great deal as I understand from my electrician.

Come to think of it, I also lack these Kinoton xenon bulb adapters for attaching the cathode to the xenon unit of the lamp house. Am happy to buy a couple if anyone have these. The lamp houses are the Kinoton Universal 2-7 kW. I can supply pictures if needed.

Sigurd

Posted by Jonathan Wood (Member # 4614) on 02-12-2014, 01:36 PM:

I think he meant 3/230 too but out of interest and this might be a stupid question but wouldn't the 3 ph rec have all the components in to make a single phase rectifier ?
Jon

Posted by Ian Freer (Member # 1940) on 02-12-2014, 02:52 PM:

Hi Sigurd

I may be making some assumptions here, but a quick search online says Norway utilises 230/240AC single phase electrical supply, so this would mean 3-ph power is already in the 360-460VAC range and no modification should be necessary?

If your power supply is typically 110/120VAC single phase then that is a different story and I should stop making assumptions...

Ian

Posted by Jonathan Wood (Member # 4614) on 02-12-2014, 03:22 PM:

As I understand it he already has it running from 3/400 and wants to run it from 3/230, 3 phase comes in both 230v and 400 v

Posted by Sigurd Wik (Member # 6131) on 02-12-2014, 03:38 PM:

Yes, Jonathan is correct. It has been installed in a cinema running on 3/400, while I have 3/230 in my cinema.

Posted by Jonathan Wood (Member # 4614) on 02-12-2014, 04:05 PM:

Hi Sigurd,
I also have a 3 phase Irem rec, its not being used right now but I always thought it was a bit like a dual voltage 3 ph motor in that it could be wired to run off 3/230 or 3/400 ?Maybe not , Im not sure but it must have been easier to make a rectifier that could run from both sources rather than have to build two different models ?
Jon

Posted by Sigurd Wik (Member # 6131) on 02-12-2014, 04:22 PM:

Hi Jonathan,

Yes, it would seem so. In IREM's info sheet they state them as two different models, EX-170GM/3-E and EX-170GM/3-US, the difference being input volt range 360-460 vs 187-230 and max input current 18 vs 23. Hard to say anything from that.

Posted by Jonathan Wood (Member # 4614) on 02-12-2014, 04:28 PM:

Just had a look at the plate on mine and its input is only listed as 400v and looking at Irem's website it doesn't look like its possible to change the input without a transformer, which as you say, would be expensive. Good luck with that ! [Smile]

Posted by Sigurd Wik (Member # 6131) on 02-12-2014, 04:37 PM:

I see. Thanks for checking, appreciate it.

Posted by Mark Gulbrandsen (Member # 72) on 02-12-2014, 05:53 PM:

The only European item I can absolutely say this can be done on is the 3-Phase motor on the Phillips FP-56 projector. Although the taps to do this are not brought out anywhere in the connection box one can find them by dismantling the motor itself and re-arranging the internal windings themselves. Takes a little doing but can be done.

Irem is still around and they have been very helpful to me in the past on older rectifiers. I suggest you contact them directly to see how the main transformers are wound and if reconfiguration is at all possible. 360 volt three phase seems to be the norm in Europe...

Mark

Posted by Jonathan Wood (Member # 4614) on 02-13-2014, 04:04 AM:

Hi Mark, most European motors are dual voltage 3 phase types , I've just changed one on a Vic 5 that was running off 3x400 to 3/230 via an inverter. The straps are usually in the term box. The D series kinoton machines are dual voltage too but changing them is as you say quite tricky as there is no terminal box as such . I've also done it on a century motor - no straps just a terminal strip but same idea. Seems rectifiers are strictly 230 or 400 though

Jon

Posted by Louis Bornwasser (Member # 3063) on 02-13-2014, 07:24 AM:

Buck/boost transformers are not too expensive. In this application, you MAY only need two of them. IREM rectifiers, by their design, are not too picky and may well tolerate some variations.

Since you are going DOWN in voltage, you may well try it as is and see if you get enough open circuit voltage and are able to adjust to the right range. That has worked for me. (I wonder if the contactor will pull in?) Louis

Posted by Sigurd Wik (Member # 6131) on 02-13-2014, 09:22 AM:

Hi Mark,

I sent Irem an email a couple of days ago but no reply yet.

Yes, I believe the 400V range is the most common in Europe. In Norway both 400V and 230V seems to be equally common, don't really know why.

Hi Louis,

Thanks, never thought of that. Will check tomorrow.

Posted by Jonathan Wood (Member # 4614) on 02-13-2014, 11:15 AM:

As I'm interested in doing the same thing I emailed them yesterday and here's the reply I received from irem this morning , looks like it's a no go unless you try the transformer ?

Dear Mr.Wood,

I'm sorry but a three phase rectifier 400V version can't works with a three phase mains voltage of 230V and it is not possible to make a single phase rectifier.
In case you are interested for a three phase 220V rectifier we can send you a quotation for the model N3-50E 220V50/60HZ (xenon lamp range 700W-1000W).

Awaiting to receive your kind reply,
Best regards

Roberto BRANDO
Professional Lighting Product Manager
IREM SpA – a socio unico
Via Abegg 75
10050 Borgone di Susa (TO) - ITALY
Tel. +39 011 9648211
Fax +39 011 9648222

Posted by Mark Gulbrandsen (Member # 72) on 02-13-2014, 12:02 PM:

The FP-56 motor although has the windings internally seperable it doesn't come from the factory with accessable taps. ONe has to rewire the internal windings. But it works out fine and runs well off a solid state motor controller.

230 volt three phase is not quite as lethal as 400 volt 3 phase would be. I've gotten bit by 230 volts once or twice over the years. Getting bit by 400 volts would certainly mean death.

Mark

Posted by Sigurd Wik (Member # 6131) on 02-17-2014, 06:04 PM:

Hi Jonathan,

Thanks a bunch for info, seems like you have a hotline to Irem that is missed by me [Smile]

Think I will be looking for a couple of other rectifiers then.

Posted by Marin Zorica (Member # 1716) on 02-20-2014, 04:12 PM:

Hmm....what exact voltages you have? this rectifiers, smps to be more precise as i see are made for three phase 400V mains, so there is 400V between each phase.....and what are you have at you're cinema, single phase 230V or 230V between each phase, because I assume you have single phase? Even, they told is not possible, i think there is a bit possibility to do it, since when you rectify 400V of three phase current you got around 500V DC and other is done by IGBT switching, you could try to rewire input rectifier bridge circuit to work like 230V grectifier in doubler way, so that would get you around 550V....but to do that you need to have a good knowledge of rectifier circuits and electronics. I remember few years ago i bought couple ORC recitifier, which were irem just branded orc. They all were for 110V ac and 1000W xenon, even irem told me it can't be made to work on 230V european main i did it and rewire a few of them.... i did that because it was cheaper to buy them in USA and ship here along with my rebuilding, than to buy new at irem.

Posted by Oscar Naveiras Calvo (Member # 8310) on 06-19-2014, 03:20 AM:

Hi:
I supposed it to late for the answer ... but we have a similar problem, with one difference. The difference is ... we are in Spain (Europe) and we have a couple of Irem EX-1500/3 but for US power supplies, 3 phases 208v.
We tried to solve the problem, but nothing works ... So, maybe you will be interested in a change ...