When is a System Obsolete?

In an era of light-speed technology development, we’ve grown to expect that equipment will end up in the trash bin long before it stops working. Sometimes a technology works so well that it’s impossible to improve. Try buying a new black-and-white TV. Color TVs do the same job, only better. When that happens, we call the old thing “obsolete.” In the consumer sector, obsolescence seems to be a good thing - consumer technology buyers want the latest and greatest of whatever they have.

However, obsolescence is a problem for industrial equipment users. After spending several hundreds of thousands, or just as often millions, of dollars building up infrastructure based on earlier-technology equipment, dumping it just because something “new and improved” has come out is fiscally irresponsible. Not only would you have to write off the old equipment (which the accounting department would rather depreciate over another two or three years - or more) and lay out the cost of the “new and improved” stuff, everyone in the plant would have to drop what they’re doing (hopefully, productive work) to take training classes on the new stuff (which is definitely unproductive). That sort of thing can put companies out of business real fast!

There are a limited number of things that can make it worthwhile to render something obsolete — that is to make you want to dump it in favor of something newer:

The need for it goes away: The need for buggy whips went away when people switched from buggys for regular transportation to automobiles.

The cost of maintaining it gets too high: As equipment reaches senescence, keeping it running becomes an increasingly expensive proposition. Eventually, it becomes less expensive to scrap it and replace it with new equipment.

Newer technology vastly improves the process: The new technology makes the process run so much faster and more efficiently that the money saved (or increased money made) is enough to pay for the cost of switching over.

The third situation has a positive spin. Technology developers always want you to think their new and improved stuff is so superior that it’s going to pay for itself in no time. In truth, however, technology doesn’t develop that way. It’s a process of continuous improvement with few breakthroughs significant enough to justify scrapping functioning equipment.

Established systems include a large number of interacting components that, at any particular time, are at different stages of their service lives. As they fail one by one, you should replace them with the most advanced equipment available. In this way, the system undergoes constant rejuvenation so that its service life vastly exceeds the service lives of its components.

To make this process work, it is necessary to have forward and backward compatibility between equipment generations. The cost of a new and improved system is a lot higher if it can’t work with older but serviceable, equipment surrounding it.

- by C.G. Masi, Control Engineering (US) Senior Editor