[GreenKeys] History - one smecc model 15 is 15Y printer mech. ..das good?? Info ...date.???.

Mon Nov 26 17:36:27 EST 2012

Well one mod 15 has a 15 y printer tech. Is it a late made unit??? Thanks  ed#

Keith Mc <acti at provide.net> wrote:

>An update / report / summary
>
>In this "issue" - mains voltages and frequencies
>(I'll talk about Phonograph record speeds, "Optical Media", and other
>things later.)
>
>Bottom line - The needs of early Edison light bulbs helped choose the
>U.S.
>"mains voltage" (wall voltage).  The needs of White Appliances (stoves,
>dryers, et al) fostered the creation of U.S. split-phase 220 (240).  
>A trade-off between the needs of lighting and motors chose our
>frequency, 
>to unify generation while minimizing eye flicker..
>
>MANY cool stories are still coming in, regarding the WHY of engineering
>choices  
>.. BTW... Some people have just said "see wikipedia" for one thing or 
>another.  For speed PLEASE add URLs in your replies!  There are
>literally
>millions of wikipedia pages, and they're not always well indexed!
>
>Mains voltage and frequency - several great references:
>...
>http://en.wikipedia.org/wiki/Mains_electricity#History_of_voltage_and_frequency
>... http://en.wikipedia.org/wiki/Utility_frequency
>For more info, also see "Electrical Energy, an Introduction":
>... http://books.google.com/books?id=UokcachsYcYC&pg=PA29
>(I'm skipping the "War of the Currents" - Edison's DC vs Tesla's AC... 
>Tesla won.)
>
>Some of the highlights
>
>Why "110V", and split phase 220 (now 120/240)?   
>Short answer:  Edison's first carbon based light bulbs required
>approximately
>100V to work.  So, 110V was chosen, to account for a bit of line drop.
>This was carried over when DC went to AC (search for "the War of the
>Currents").
>
>Cool Side Note - Production batches of early light bulbs were
>"selected" 
>for voltage.  There even was some "secondary markets" for the off-value
>
>bulbs.  Local generators that could be altered in voltage could take 
>advantage of the supply of them.
>
>Voltage Creep (110->115->117->120V)  - Slowly increasing the voltage
>over many years appears to be a cheap way to get more utility out of 
>the same wiring as they added customers and loads.  Since the more
>modern metal filament bulbs can be made at any voltage (and most
>motor's speed is most often a matter of frequency, not voltage) 
>this wasn't a big problem.
>
>Split phase 220 (240)  
>110V (now 120V) is rather low for power "white appliances" (stoves,
>dryers, etc.)
>So a split phase 220 (now 240) was set up, with two legs of 110/120
>that add together, for high energy appliances.
>
>Why 230V in Europe?  Again, when METAL filament bulbs first came 
>into existence, they could be made for ANY voltage.  So the forward 
>looking German company AEG (descended from Edison's original 
>European company) "bit the bullet" and converted their ENTIRE 
>system to roughly double the voltage.  They helped their customer 
>base change over their equipment.  In the end, it turned out that 
>customer retrofit was more than offset by the savings in power line 
>upgrades, as this halved their line currents.  Unification set the
>present 
>European voltage standard.
>
>What's interesting to note is that unlike split-phase 220/240 in US,
>Europe is actually a 3-phase 400V system, giving you the 230V per leg.
>3-phase power has a LOT of advantages (which I won't go into here),
>and in fact is how the majority of our grid works too.  (Now WHY we 
>don't supply it to residential homeowners is a whole 'nother subject!)
>
>Advantage to Makers - This makes home owner/maker 3-phase power 
>MUCH more available in Europe, than the US.   Even now, if you want 
>3-phase in a US residential area, you often have to pay for a 
>"special drop"  The utility runs new wires from your house all across 
>your neighborhood to wherever it can be found. YOU pay for that, 
>plus an additional, different local transformer, AND more poles should 
>the present ones be at their limit for weight.... Not cheap!   
>
>In the past, some US Makers created "3-phase rotating converters" 
>out of old 3-phase motors, to save money vs "buying a drop". 
>Today, the recent availability of cheap solid state Variable Frequency 
>Drives [VFDs)] has changed all of that.  You can now easily create 
>3-phase power at home of variable frequency to run a personal mill 
>or lathe from 120/240 split-phase rather cheaply, without requiring 
>an expensive 3-phase drop any more.  (You also get a speed control
>out of the deal, so they are very popular.)
>
> - FREQUENCY CHOICES - 
>
>Bottom line - There's a trade-off, between what is best for 
>motors and transformers, and what is best for lighting.
>
>In the early days, you had two different generating systems,
>and they co-existed.
>
>Very LOW frequency (eg 25Hz) WAS most convenient for motors.
>It was also first generated by slower moving equipment.  
>In fact, the lower the frequency, the better in SOME ways, as 
>it minimizes certain kinds of losses.   Many motor systems ran in 
>the 16-2/3 (1/3 of 50) to 25Hz range.  There are several low 
>frequency systems still operating, for industrial customers 
>(some Niagara Falls generators, some electric rail systems, etc).  
>
>BUT, low frequency causes perceptible flicker in lighting.
>So for LIGHTING apps, you are mainly driven by the needs of the EYE, 
>and want HIGHER frequencies. Some generating systems for lighting
>went all the way up to 140Hz.  
>
>Having two separate frequency systems got expensive in infrastructure.
>Rotating frequency converters COULD up the frequency from the 
>"motor supply" 25Hz up to 60Hz.  But, that isn't nice mathematically.
>The "common denominator" was large enough that it required very
>large machines to do it.  (30->60 is easy had THAT been chosen, 
>but 25Hz was entrenched. Hmmm...)
>
>So... To make motor and lighting systems compatible without requiring
>"frequency converters", you want to choose "the LOWEST frequency 
>that eliminates perceptible flicker".  That means about 100-120
>flashes/sec 
>minimum, or 50-60Hz of full cycle waves.  (50Hz = 100 half cycles/sec, 
>right around the flicker rate of MOST people's eyes,  60Hz = 120 half 
>cycles/sec, a bit above most people's eye flicker rate.  Some Americans
>
>can notice the European 50Hz flicker when they travel there...)
>
>50Hz vs 60Hz  - Lots of different stories abound.  But from what I've
>found:
>
>In the early days, there were two BIG camps in play - Edison & 
>Westinghouse (Tesla) in the west, and Germany's AEG in Europe.
>
>Around 1900, there were lots of frequencies in operation, ranging from
>16.667Hz up to 140 Hz in operation.   But the market eventually settled
>
>on two - 50Hz in Europe, and 60Hz in the west, so I'll only talk about
>them.
>
>Big supplier AEG in Germany chose 50Hz, and Europe eventually went to
>it.
>
>Some thought arc lighting looked a BIT better with 60Hz, and it worked 
>better with clocks. 60Hz transformers were also SLIGHTLY lighter than 
>50Hz transformers.  So, big supplier Westinghouse moved from higher 
>frequency systems down to 60Hz.  Eventually, the west standardized 
>on it, for compatibility.(eg Mexico changed over from 50Hz to 60Hz).
>
>Interestingly, some places (like Japan) are still split, based on early
>purchases 
>of equipment long ago from either US or Europe.  The western part of
>Japan 
>(Kyoto and west) uses 60 Hz. The eastern part (Tokyo and east) uses 50
>Hz. 
>There is even a line of massive high voltage DC converters at the
>boundary 
>line, trying to connect the two systems, and keep them compatible.
>
>BUT... This is NOT STABLE, even today!
>
>The US used to make sure the total count of cycles/day stuck very
>close to 60Hz, so that AC driven wall clocks would stay stable.
>But with the advent of GPS synced clocks, and "crystal controlled 
>everything" (micros, etc), the US is playing around with dropping that 
>requirement to make shuttling power from zone to zone easier to 
>accomplish.  (One generator "leads" or "lags" another, to transfer load
>
>and power between them. But this can SLIGHTLY change the line 
>frequency.  If you are "counting cycles" to keep time, this can become
>a problem.)
>
>A list member from Kuwait also wrote they are using 240/415VAC 
>as the nominal single phase and three phase power line voltages.
>But the local ministry isn't keeping them well adjusted.
>
>He wrote:
>> At home, we had up to 257VAC phase to neutral for a few weeks, 
>> and I was going through incandescent lamps quite rapidly.   
>> Line voltage is now much closer to the 240VAC nominal.
>> 
>> I can tell that the power ministry doesn’t do well on frequency 
>> control, as the power line time base driven clocks in the stove 
>> and the microwave oven aren’t very accurate.  The stove clock 
>> is about 30 minutes ahead of real time now.
>
>A few years back I too was once in a subdivision, that could jump from 
>90V one day to 135V the next in the summertime.  My early Intel 
>development system wouldn't boot at 90V, so I added a Variac on it 
>to help "keep it in spec".  But one morning I forgot to check the line 
>voltage before powering up the computer.  Though the weather was 
>similar, line had made a HUGE jump up from the day before. 
>Unfortunately, my Variac now compounded the problem.  
>It ended up putting well over 150V into my computer, and fried some 
>VERY expensive early disk controller boards.  That shut me down for 
>several days (and cost me a big chunk of change, to fix...)  
>Needless to say, my "morning rituals" were vastly improved after that!
>
>So even today, things can vary widely from place to place.
>
>I hope others found this as interesting as I did...  
>
>BTW... I've also found info on "why 78, 45, and 33-1/3 for records" 
>(and other similar trivia).  But this was long enough. I can post 
>that information at another time.
>
>- Keith Mc.
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-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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