Evolution - Revolution - Techno Modernization Solution

A Technical Evolution [1]

In this series of blog posts, I intend to make some searchable notes on the evolution of control systems hardware.  I say the word evolution carefully here.  What I can see however is that regardless of availability of key technical components, certain evolved arrangements of technology create a requirement for their own continuation. I will be exploring a number of features of this kind of evolution.


Why is it that I have some assemblies doing the most basic function, made of some of the oldest components, often difficult to source, yet to replace them is almost unthinkable ?

In the figure, we can see that the bicycle has evolved extensively in 150 years, from an initial version made in Deutschland to a version circa 1970 in the USA.  I can say that a visit to a cycle shop down the road, last weekend showed nearly all bicycles were of three forms.  Road Bike, Mountain Bike, Racing Bike.  There was a relatively new form though.  The folding bike.  This bike look like a squashed wheelchair, but I was told - "sure, not very popular, but ok for the commuter, who wants to fold it up,... under the desk ...".

What really has changed about the bicycle ? How interchangeable are the parts ? Can you still buy parts for the older models ? Are the materials stronger, better, lighter and less expensive ?

A lot of things have not changed, in particular the quantity and arrangement of the components. Two wheels, two pedals, a seat, the general height of the bike. "Do you want a 26" bike ?" is still the key question, and has been for at least 50 years that I know.  The general height of people has not changed significantly, that it would alter the general height of the bicycle.  In case of variation, there are adjustments available to the configuration.

Yes, I can still buy parts for obsolete bicycles.  I can still have someone repair and older bicycle, providing he knows about it.  I may find that some of the newer parts can be adapted for the older models.  But I don't really need to.  A bicycle is generally a commodity item.  I can always buy a new one and use it instead of the old one with very little adaptation of lifestyle, and no hard feelings about the old bike, I can find space down the back of the shed to store it.

With complex control systems, life tends to get a bit more complex.  The complexity is because a control system for a plant, or a SCADA system for infrastructure is almost like the nervous system in a complex organism.  It reacts to stimulus and protects the plant. It reacts to higher level requirements and changes a setpoint for example.  Replacing control systems and scada systems, might sound easy, and is very often sold as 'easy'. In reality as time goes by, the control system becomes almost inseparable in some ways from the plant.

So the evolution of Control and SCADA system technology is impacted by their requirement by end users for long term support over many years. Not 1,2,5,10,20 but more like 50 years.  In my prior post, I briefly referred to the use of the C25 Remote Terminal Unit.  This original Leeds and Northrup design, was actually originated in 1932, and through several re-incarnations, became the C25 in around 1980 and is still in service in many locations today in 2012.  How do we support these ?  Invensys has a life cycle policy for the support of control systems equipment, which you can investigate more fully on our website, which covers the support of all the Foxboro control systems equipment.

To look at the C25 [prior post] is not as elegant or evocative of speed and finesse, but it's function as almost the dendrite of a central nervous system, acting on the muscles of electric power grid infrastructure in a city is still a critical function for our electric powered society in general. Today if asked, we would provide a more modern equipment which can do the same function, being the Foxboro SCD5200.  There remains through, some surgical engineering to remove the old C25 and replace it in such a way to preserve it's function with as little disruption as possible.









By derivative work: Manuel (Diskussion)Bicycle_evolution-en.svg: Al2 (Bicycle_evolution-en.svg) [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons