Film-Tech Forum ARCHIVE: Commenting on: Irem Rectifiers

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Posted by Demetris Thoupis (Member # 833) on 03-17-2007, 01:31 PM:

I thought that it would be nice if we could start some topics focussed on specific brands and self reviewing equipment that we use for years and years! I would like to make a start by commenting on Irem Rectifiers. We have been using them for many many years and have found them to be very reliable with the only exception of some burned diodes every once and a while. I believe that Irem rectifiers are the BEST in the market. The only downside of them, if you can call it downside, is the weight and size of them. I believe though that now that is also fixed as IREM has given us the oportunity of using Rack Mounted Xenon Power Supplies which can either be single or three phase and electronically controlled either from the front panel or via RS232 control. We have been installing Irem rectifiers for many years and also moving from old closed cinemas to re-opened cinemas these rectifiers and have never failed us. A Bravo to Irem for making such tremendous products.
Demetris

Posted by Kevin Raisler (Member # 1761) on 03-17-2007, 11:11 PM:

I've only ever used IREM and have no need or curiosity for anything else. Smooth Clean Light with with no fuss. [thumbsup]

Posted by William Phillips (Member # 1162) on 03-18-2007, 06:59 AM:

N3-75 Rectifier very good. Time will tell on my newer N3-100

Posted by Mark Gulbrandsen (Member # 72) on 03-18-2007, 09:14 AM:

In my exerince with them over the last 27 years typical lamp life with Irem's is no where near as good as with Christie's rectifiers. The tension adjust on the movable core needs to be adjusted often when they get older because of the compression set of the fibre and phenolic spacers. This is particuluarly a problem on the larger Irems... 4KW and up. Over all they are a so-so deal. Christie is in my experience still the winner by a huge margin.

Mark

Posted by Louis Bornwasser (Member # 3063) on 03-18-2007, 10:15 AM:

Christie is reliable but inefficient.

IREM (except for occasional diode or contactor) is utterly reliable and as for bulb life: I have never removed a 2k Osram below 4500 hours with 6000 "doable." I do understand that ripple is high, but, with the very long bulb life I have experienced, I have come to the conclusion that ripple must be good, at least when IREM does it.

I have similar results with other bulb sizes.

Because of ORC, Strong switchers, and old Strong electronic power supplies I avoid electronic "intensive" rectifiers. Especially now, with lead free arriving, the reliability will be unacceptable. I have had good luck with Christie & IREM.

FYI: When you send Osram a warranty claim; the bulb is tested using standard IREM equipment. In years gone by, they would light a bulb that would not work on any other rectifier. Louis

Posted by Mark Gulbrandsen (Member # 72) on 03-18-2007, 12:41 PM:

quote: Louis Bornwasser
I have never removed a 2k Osram below 4500 hours with 6000 "doable."

Louis,

6000 doable hours is nuttin but I won't also say that short life is in part the problem of the Osram lamps since thats what I see around here too. We typically get twice that life with Christie rectifiers running Christie lamps. There is one 2kw in St George at 19,000 hours now and these lamps come out clear. They just begin to have unstable arcs. Efficiency is irrelevant at this long life so the low cost of the lamp has already offset any extra trivial power costs. The Irem's in this area typically provide rated hours and then some... perhaps 500 to 750 extra hours... thats nothing to write home bout.

Mark

Posted by Richard Fowler (Member # 893) on 03-18-2007, 12:44 PM:

Older N type IREM, I feel, had a better build quality. The IREM switchers I serviced had connector and fuse problems. Proyecson makes a great standard and switching series which is superior to IREM...other manufacturers are buying them under private label.
As for rack mount rectifers there are several sources. Our rental hardware is based on 1/2/3000 watt units for projection and spotlight and all of these are housed in 5.75" high rack mount modules which where custom built.

Posted by Scott Norwood (Member # 30) on 03-18-2007, 02:04 PM:

I have a pair of IREM P1-X30B rectifiers (500w) in my home setup and they weigh a ton, but I feel like some of the components are a bit on the cheesy side. I had a fuse holder disintegrate on me a week or so ago and (after removing a couple of dozen screws to open the unit) I replaced it with one that cost about $3 at the local electronics parts place and which was of visibly higher quality. The little cooling fans inside these have soft metal blades that are easily bent.

Maybe they just went cheap on these low-end models which, admittedly, aren't likely to be found in commercial theatres.

As for the larger IREM models, I don't have any real comments, except to say that I am happy that I don't have to move them, as the ones that I have seen have all been extremely heavy.

Posted by Demetris Thoupis (Member # 833) on 03-18-2007, 04:15 PM:

What would be interesting to see is comparing the product in terittories. US uses 110V while Europe use 230V. That might be a reason for many facts. Here for example Christie projectors which have inverters inside to convert 230V to 110V had problems with burned motors often. Once installed a UPS the problem solved somehow but not completely. We never had this kind of problem with Cinemeccanica or Kinoton projectors. This might be the case with Irem rectifiers. If what Mark is saying is true, 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.

Posted by Louis Bornwasser (Member # 3063) on 03-18-2007, 04:55 PM:

Demeteris: I think the 60 Hz vs. 50 Hz is more important when dealing with inductive loads like motors and rectifiers. IREM's run stone cold in 60 Hz countries; they heat somewhat in 50 Hz areas. That is why 2000 watts works OK on 75 amp rectifiers, while "you guys" limit that load to 1600 watts. Louis

Posted by Mark Gulbrandsen (Member # 72) on 03-18-2007, 05:49 PM:

quote: Louis Bornwasser
IREM's run stone cold in 60 Hz countries

Louis.. pleeze... that is just not true!! You must not have any 4kw or larger Irems running. Come out here and I'll let you feel the heat [evil]

. In fact next time I open one up to adjust it's core from vibrating I'll be all to happy to measure the temperature rise for you.... running 140 amps its significent.

Mark

Posted by Steve Guttag (Member # 268) on 03-18-2007, 05:53 PM:

Irems have their ups and downs. I too find that a lamp fired on a Christie power supply will last far longer than fired on an IREM. I've never had really great life out of IREM powered lamps. Don't run an IREM close to the top of its range...it tends to have harmonic issues that will put noise on the AC line too (had this measured as to why the circuit breakers were heating up when a pair of N3-180 rectifiers were outputting about 160 amps.

IREM absolutely undersizes its contactors for the US market...we run on 208, not 230 nor 380 (some of Europe). Some 208 sites are closer to 200 too. As such, the input current is higher to compensate (power is power). IREM has raised the contactor ratings over the years but in my opinion, not enough. For the smaller rectifiers, one should use an A26 series rather than the supplied A16. For the larger rectifiers (100s to 180s) use an A40 contactor rather than the supplied A30. I know some to have just replaced the fancy 4P contactor with an off the shelf Square-D 50A contactor without problem either (in the US, no one uses that latching feature the 4th pole brings).

All IREMs hum...yes you can adjust them but they will be humming again soon...this goes on until you run out of adjustment.

They size their diodes to just barely work...why? The cost of say an 85A/1600PIV diode versus a 40A/400PIV is not significant in the cost of the rectifier. To top it off, they don't have good surge supression so they are more likely to go. Putting surge supression on the AC input will go a long way to long diode life. This is also true of Christie...they chew through diodes if surge supression is not added to the rectifier's AC input.

Posted by Marin Zorica (Member # 1716) on 03-18-2007, 06:31 PM:

I have experience with N3-110, on 3phase, 50Hz....work's great, without heat and noise.....I really think they will be noisier because has magnetic shunt regulation!

This conversation give's me clue to take oscilloscope and measure ripple on Irem....

But I know that Irem produced a SMPS PS for Prevost portable machines P86X to power XBO and I know for couple of that portable pair...and everybody have problems with that PS!

But I hate that they don't have choke on DC output...which compensate AC ripple good. Here many rectifiers which are primarily for carbon arc uses to power XBO, so then we mostly installed choke od DC out to get lower AC ripple!

I built myself rectifier for a 500 XBO, running on 30A have 5% ripple and is single phase!

Posted by Steve Guttag (Member # 268) on 03-19-2007, 12:44 AM:

For the N3-100 and G3-100 and smaller, the choke on the output is an option called the "AFU". The choke is standard on the N3-150 and G3-150 and above.

Oddly, Strong has stopped supplying the choke on their High Reactance power supplies. Too bad. I think the choke helps not only with ripple but back spikes from the igniter reaching the diode stack on ignition.

Posted by Marin Zorica (Member # 1716) on 04-04-2007, 05:52 PM:

Yesterday I went to one location and measured AC ripple on IREM N3-110....it's 5,3% at 85A!

Posted by Steve Guttag (Member # 268) on 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.

Posted by Tim Reed (Member # 137) on 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).

Posted by Stephen Furley (Member # 1277) on 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.

Posted by Gordon McLeod (Member # 33) on 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

Posted by Stephen Furley (Member # 1277) on 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?

Posted by Gordon McLeod (Member # 33) on 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

Posted by Steve Guttag (Member # 268) on 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.

Posted by Mark Gulbrandsen (Member # 72) on 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

Posted by Gordon McLeod (Member # 33) on 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