My return to Classic Cmp - San Diego, software archive, etc.

[Chuck Guzis]

On 18 Dec 2008 at 6:05, Dave McGuire wrote:

>    Yow...What was the application?  I'm familiar with those Honeywell  
> CV supplies; they're nowhere near as stable as a Weston cell.  Far,  
> far, FAR more rugged though, and resilient to temperature  
> shifts...which Weston cells are not.

Almost all were for process temperature control--from ingot soaking 
pits to solutions on the continuous galvanizing line.  "Rugged" was 
probably more important than "stable", but I think it was more to 
avoid the issue of once-monthly replacement of dry cells and 
maintenance of the associated calibration mechanism.  The big square 
black 1.5v cells (made by National Union?) were used extensively, 
instead of the smaller round No. 6 ones.  On an open mill floor, 
temperatures could go from sub-freezing to Saharan.  Dirt, of course, 
was everywhere.

Right about this time, I recall that IBM had installed a computer for 
process control in one of the new plants. Sadly, I don't recall any 
details.  Perhaps a 1710 used with the BOF.

Like a lot of American heavy industrial operations of the time, the 
mill was a wild mix of period technology, much of it pre-war and much 
running from 25 Hz power.  Up until that computer, it seems to me 
that the most sophisticated stuff was pneumatic--full analog 
computers, with P-V and V-P converters, pneumatic amplifiers, square-
root extractors, differentiators, integrators, etc.  "Wiring" done 
with quarter-inch copper tubing and compression fittings.  If the air 
supply was kept clean, the pneumatics were pretty much 
indestructible.

Earlier controls were mostly hydrostatic types of the diaphragm-and-
jet type.  Keep the tank filled with Pydraul and you were good for 
decades.  There were very few electrical-only process control 
systems, mostly restricted to non-critical processes.

Cheers,
Chuck
(I hope there's enough "computer" content here not to irritate)