Fuse instructions ?

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jakematic

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While filing my latest AutoScans away, I noticed this old picture.
It is of the instruction manual for my bench power supply.






I dunno about you, but if that power supply is working as a 'crisper' I have no intention of opening it....
 
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Bruce

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Its never good to let the magical gray smoke out of electronic devices... it's the only thing that makes them work. So a crisper? Makes me think gray smoke.. hot stuff .. all not good when running a power supply! But it beats my 10,000 pound jumping power supply! (600KW) See if we can drag Uwe into this one! A oops of big magnitude we made. But, no gray smoke on that bad boy! No crisper either. Still 10,000 pounds jumping an inch off the floor - that was impressive!
 
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jyoung8607

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... But it beats my 10,000 pound jumping power supply! (600KW) See if we can drag Uwe into this one! A oops of big magnitude we made. But, no gray smoke on that bad boy! No crisper either. Still 10,000 pounds jumping an inch off the floor - that was impressive!
Uh, don't leave us hanging... we're gonna need the full story on that one. :)
 
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Uwe

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Transformers tend to get jumpy when their cores are sporadically pushed into saturation.
 
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Zenerdiode

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The 'magic smoke' is sometimes referred to as the genie. With a flash and a bang and a cloud of smoke - the genie is released...

...and you can't get him back in there without a major strip down. :(
 
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Bruce

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Uh, don't leave us hanging... we're gonna need the full story on that one. :)
So we made an Ooops.. Uwe and I - mostly Uwe - developed a power supply for large industrial electrical vacuum furnaces. This one was large! Could hold a 60 ton payload that was 24 feet long and up to 10 feet in diameter. The entire furnace took 1.3 Megawatts. We're playing in the big leagues here.

So, we developed a power factor corrected, fully digital power supply that used phase fired SCRs to control power. We switched power between taps on a transformer using an averaging algorithm. Changing taps on the fly on large inductive device is not trivial as our hearing and eyesight would attest to on the several prototype mishaps that occurred. <BANG and Flash Before magical gray smoke!> And these were on 10Kw or less.

Well, our prototype units used what are known as easy firing SCRs. Give the device a nice electrical kick and they start! For the mother of all furnaces, we needed to use power devices that could handle continuous 800 amps at 460v ratings. These are massive devices and known as hard firing SCRs. We thought we had a big kick to start the scrs. We learned it was not as big as we thought.

Because the scrs were not conducting equal half cycles, the transformers had a DC bias in them. What does that do? If large enough, the core of the transformer becomes "saturated" - the magnetic flux can no longer change with the change in current in the primary winding. A saturated core presents to the primary connection, only the winding resistance as the reactance of the coil drops to near zero. In effect, it becomes a dead short across the line!

Now, because the DC bias was just enough, it only saturated for the peak of the line voltage - and that for just a few microseconds - maybe as much as 100 microseconds. In that time, enough energy was dumped into that short to cause a tremendous thump in the transformer with the huge inrush of current. When you have energy of that magnitude, it has to go somewhere. The force of that short was enough to lift the 10,000 pound cabinet off the floor the one inch I mentioned! Talk about needing to change one's shorts! (Pun intended!)

Now, when this first happened, I was on vacation. Uwe had left the business and was thinking things VAG-COM. The shop manager calls me on my cell in Raleigh, North Carolina, and asks, "What do I do with dancing transformers?" Now this guy was always pulling practical jokes - so I'm like - "Yeah right Bob." He says, "I'm serious! Here, listen." He holds the phone out and I can hear the cabinet slamming to the floor. And I turned pure white! I nearly passed out as he added, "And we have 30 tons of titanium valued at over $2M in there right now on a extended cycle that heats for 72 hours and then cools for 48 hours. We can't stop the furnace or we ruin all of the material." "How far into the cycle are we," I asked. "8 hours!" Oh .......

I gulped... and I told him, "I need to sit and think. I'll call back in about 10 minutes." Uwe will have to comment as I do not remember if I called him at that point. I don't think I did. I decided to have them unbalance the heat distribution just a little - very small amount so we could back the power down on that 600Kw section of the furnace. We did and the dance terminated successfully. The heat run finished without further issues and I arrived at their plant to begin studying the problem. Uwe and I made a correction a week later and we never had dancing big guys again until 2 years ago when I performed a song and dance at Automechanika - but then that is another story!
 
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jyoung8607

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Fun times! :) Industrial process guys always have the best stories. I've heard some great war stories about PLC programming gone horribly wrong...
 
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Uwe

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Changing taps on the fly on large inductive device is not trivial as our hearing and eyesight would attest to on the several prototype mishaps that occurred. <BANG and Flash Before magical gray smoke!>
Yeah, in fact, everyone else in the industry who saw what we were doing shook their heads and said: "You can't do that, that's not possible, you'll saturate the transformer's core on the first cycle when you switch taps".

What they didn't understand is that when you have software control over exactly when the SCR fires, you can do some tricky things that prevent that. This was in the early 1990s and everyone else was still doing their control using fixed logic rather than software.

Controlling all that power was a NEC V25 (8086 superset). IIRC, I had a whopping 16k of code running the whole thing (written in straight assembly language, of course) but I needed the 16 bit CPU to do the math fast enough. I'm sure I still have the source code and schematics for it somewhere on one of my systems. :D
 
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DV52

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Yeah, in fact, everyone else in the industry who saw what we were doing shook their heads and said: "You can't do that, that's not possible, you'll saturate the transformer's core on the first cycle when you switch taps".

What they didn't understand is that when you have software control over exactly when the SCR fires, you can do some tricky things that prevent that. This was in the early 1990s and everyone else was still doing their control using fixed logic rather than software.

Controlling all that power was a NEC V25 (8086 superset). IIRC, I had a whopping 16k of code running the whole thing (written in straight assembly language, of course) but I needed the 16 bit CPU to do the math fast enough. I'm sure I still have the source code and schematics for it somewhere on one of my systems. :D
Uwe: writing code in assembly language - now that takes me back to another time, Bet that you didn't store the code on ferrite core memory as I used-to ( surely you don't go back that far).
 
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Uwe

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Nope, no ferrite cores. I'm only 55. :D
 
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DV52

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Nope, no ferrite cores. I'm only 55. :D
Uwe: only 55? That's disgustingly young - but it's not your fault!
 
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Bruce

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I'm sure I still have the source code and schematics for it somewhere on one of my systems. :D
If you don't, I know I do! We should have patented that idea Uwe. It worked... it could still be working.... It has a place.
 
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Bruce

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Uwe: writing code in assembly language - now that takes me back to another time, Bet that you didn't store the code on ferrite core memory as I used-to ( surely you don't go back that far).
Not only do I remember storing code in ferrite core memory, but I also had to bootstrap the computer by toggling switches and entering the data in Octal! (not HEX) My earliest assembly language job, we didn't even have a computer to do the assembly of the program. We had to sit down and do it by hand ... compile on paper and then zag the stuff directly into memory. Oh those were the days... you all are spoiled with your toys these days.

One of the reasons I stayed in hardware was I wanted to touch things and see that magic grey smoke that made it all work! ;)
 
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jakematic

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I also had to bootstrap the computer by toggling switches and entering the data in Octal! (not HEX)
In EBCDIC I hope :p


I started doing this:




Which made these seem like a DREAM come true.
Note that's a fancy one with not one but TWO drives.
Excellent for defragmenting an FRL file after one of my keypunch 'girls' (as we called them back then) totally screwed up the order entry process.
Ahhh... I can still hear it going KACHUNK KACHUNK KACHUNKKACHUNKUNK BRPPPT KACHUNK




I do miss lights to tell you what is actually happening.
This was the control panel of the 5360 I started my career on right after we migrated from S/3.
There's an identical one framed on my office wall, and a second somewhere around here...

 
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Bruce

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Jakematic, the teletype and zagging paper tape was an improvement over the switches... then came the cassette tapes! Wow we were now light years ahead in getting things loaded!

I was not in data centers - I was designing machine controls. So, we had low budgets for tools - "Why do you need all that equipment to make a machine go?" Oh those early days were fun. The youngsters are constantly saying, "What? No way!" They have no appreciation for the power of the smart device they use as a phone. The smart devices have Gigabytes of memory in them - we couldn't conceive of Gbytes. We were pleased to have multiple Kbytes!
 
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jakematic

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Never got a chance to work on the switch input machines but remember well applying patches via that control panel with 4 people double checking my entries !
LOL, I still have a love/hate relationship with 9-track tape... we won't even bring up QIC :rolleyes:

You made me think of a meeting circa 1988 that seriously agitated me.
"What do you mean you need 32K for that PC ? I run an entire Enterprise with 54 users, 2 printers, 4 barcode scanners and a tape drive in 128k !" I screamed....

Yep, I configure tera/peta/exa byte storage systems and multi-terabyte memory now, but still catch myself prefixing mega.
After installing the first Winchester 10MB in a 5150 I thought "This is the end... nobody will ever need more storage than this..."

Ironically "Project Chess" developed "Acorn" down the street from an office of the company I now work for.
It's a restaurant and offices by the sq ft now... at least it's not an Enterprise Rent-a-Car like my old branch <sigh>
 
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DV52

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Not only do I remember storing code in ferrite core memory, but I also had to bootstrap the computer by toggling switches and entering the data in Octal! (not HEX) My earliest assembly language job, we didn't even have a computer to do the assembly of the program. We had to sit down and do it by hand ... compile on paper and then zag the stuff directly into memory. Oh those were the days... you all are spoiled with your toys these days.

One of the reasons I stayed in hardware was I wanted to touch things and see that magic grey smoke that made it all work! ;)
Bruce: finally, someone who appreciates what REAL programming is. Having to set-up each line of code by toggling a row of switches and then pushing a button to enter the code. You know I don't miss those days at all - life's too short to be doing that stuff!
 
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