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Author
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Topic: Single-phase Rectifier question
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Mark Gulbrandsen
Resident Trollmaster
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Posts: 16657
From: Music City
Registered: Jun 99
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posted 05-09-2004 08:21 AM
Well, here we have another dealer thats again giving out WRONG INFORMATION and I've got to wonder if this is the same guy that trashed the Panastereo??? There are DEFINATELY NOT any high failure rates with Strong Switchers. In reality what it seems to amount to today is that there are people that hate them or people that love em somewhat based on the problems thay may have had with the early units. Yes, there WERE many mechanical type problems with the early Strong switchers but that was a long time ago and definately not so with the new units. The downside is that you can't repair it if it does break down. Simple as that!! I can think of only one location here in SLC that had many problems with them. Since they do their own service work I can't honestly say what the problem was, but I suspect that it was not the rectifiers. A good example of the reliabliity of these units are the Phil Hill designed Iwerks 15/70 installations that have three 7kw units in parallel cranking out 375 amps all day and night long with out any failures.
Out here in the mountain states we have probably close to 150 Strong switchers in just about every type of cinema situation you can imagine and we have less trouble with them than we do with standard rectifiers and failing diodes with the remainder of our close to 400 locations. We have sites that run switchers that have had them for a decade and had zero problems....and those are some old switchers by todays comparisons. Keep in mind that they are in plex's, in small town situations, and situations with occasionally dirty power.... overall we see one or two switchers a year get exchanged.
As for the older Strong high reactance units, they only have barely passable ripple and inrush current levels when in good running condition while the switchers high frequency ripple is pretty much invisible to the lamp and inrush current is very well controlled. Being more efficient they also put out far less heat and draw far less current. Obviously Strong had to do something about these old Hanovia built high reactance designs and decided to go the switcher route.
If you want a good iron core rectifier then look for a Christie, an Irem, or a Kneisley ...prefrence in that order. Far as I know Christie never made any single phase 2kw units but the other two companies did and still do.
Here are some advantages and disadvantages of each type......
High reactance type...
Advantages.... Easy to repair, cheap to buy used
Disadvantages... Extremely heavy, can be very power hungry, higher ripple, genreally around 10% and high inrush currents that can go to 5 to 6 times the operating current, poor lamp life, transformer windings that come loose and buzz, diode failures, blocking diode failures, noisy whining fans.
Switcher....
Advantages... Light in weight, smaller, high frequency ripple is invisible to the lamp, well controled inrush current levels, extremely long lamp life if you want to push it there, low power consumption, low heat produced, same unit runs on either single or three phase, LED array to aid in over the phone diagnostics. Flat R/A price charged by Strong for an overnight replacement.
Disadvantages.... Can't be field serviced easily but it is possible, Sensitive to dead short circuits on the DC line, Lots of hardware to remove to get inside unit, uses solid state relay instead of a regular contactor eliminating the usual clunk sound that some techs normally use for over the phone diagnostics. Some of them have the noisy whining fans.
Hope this helps....
Mark
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Jack Ondracek
Film God
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Posts: 2348
From: Port Orchard, WA, USA
Registered: Oct 2002
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posted 05-11-2004 10:28 PM
I have two of the older Strong switchers. Other than keeping the input grates clean, I open them up once a year to make sure the DC connections are tight (which, by the way, is recommended by Strong). I have had zero problems with these power supplies. I recently purchased two of their newer 7kW supplies, so I could retire some very old ORC and Strong supplies I have at the drive-in. Zero troubles with those switchers, too.
On the other hand, I have replaced diodes in every model and size of high-reactance supply I've ever owned... Strongs at 2 and 4kW, and a couple of ORC 4kW supplies. Nothing in the booth may be fail-proof... but over the years, I haven't had to pay nearly as much attention to my Strong switchers as I have my high-reactance supplies.
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