Changing process control systems

Ian Heathcock from Siemens Industry Automation examines the changing factors that are influencing management decisions to instigate change to current control systems:

Seeking to improve, enhance or change a process control system can often be a fraught and potentially costly exercise – both in terms of the personnel responsibilities required and the associated expenditure. 

Drivers for change to an existing system are often rooted in individual company necessity which can range from risk management requirements to protect production capabilities, or a need to support more effectively business expansion through superior levels of operational efficiency. 

Change costs, so why do businesses spend thousands of pounds each year changing their control systems? 

Not only does it raise expenditure in terms of physical pieces of hardware that need to be altered, but there are also a number of other areas of cost that need to be considered:  for example, the software and engineering costs of both the customer and the vendor – as well as the real potential for lost productivity while the old system is replaced with the new one.

At its most basic level, the driving force behind many businesses considering a change to their existing control system is one of obsolescence.  As in any industry linked into the use of computer technology, the lifecycle of the very software and hardware it relies upon is cyclical and can often be short in terms of timespan. 

However, just because a piece of software or hardware is ‘out-of- date’ is not a valid enough reason to implement significant change.  Rightly so, the financial controls within the business demand more than just a replacement to get the latest technology. Indeed, the new system has to be justified by more acceptable reasons and bring enhanced and quantifiable benefits.

One such benefit is ‘risk management’ and to be more precise, risk management to alleviate the threat of non production. 

Computer technology has a limited shelf life, especially where rotating parts such as hard disks are concerned. Since most modern control systems now rely on PC-based technology for their operating stations there is the significant issue that any computer technology over five years old may start to have an increased risk of failure. 

However, simply replacing worn out or failed parts is not always an option.  In five or more years the industry will have moved on and so with it the technology solutions. Businesses can’t simply buy another disk to replace the failed one. The interface will have changed rendering the old one obsolete.  This will be true for most of the key parts of the computer also. 

So companies put a new PC in?   Again, this could be a decision to regret as the operating system and the existing control system software that goes on the new computer are most likely to be incompatible.  

With most systems on the market today after five years there will be an increased risk of them failing.  With such failures the key window on the process of the operator stations will not be available and the process will not be able to operate and production will cease. 

A few days lost production can easily pay for a control system changeover so with the correct arguments and a strategic approach to protect future production capability, it is not hard to see how it can be financially justifiable to seek system change and enhancements.

Risk of failure can be viewed as a very negative reason for changing.  A business doesn’t want to do it but will have to out of necessity as a failed system will lose it business production, real revenue streams and, in worst cases, its customers.

There are however more positive-based reasons why businesses look to change control systems.

In some scenarios, a successful business may be expanding and adding new products into its portfolio or increasing volumes of its existing products.  In this situation the older system may have been able to be expanded, but it will most likely still only operate at the existing efficiency. 

Ideally a business will want to expand its process capability and flexibility, but reduce its costs to make it more competitive.  This is where an up-to-date control system can deliver benefits that have been built into it from the start. 

With better information presented to the operator and benefit-driven functionality such as diagnostic maintenance and energy management, a process plant can be run more efficiently with optimised control and reduced occurrences of shutdowns due to unexpected failures.  

Gone are the days of making your process “fit” into your control system.  Today’s control systems offer the flexibility to match your process requirements.

Sometimes overlooked, but often significant in a business decision is the support that is available for the current system and the quality and cost associated with it.

A business that has had poor and costly support in the past will look elsewhere when it next needs to change.  In more severe cases this may be the most significant reason for an early change of system. 

With today’s just in time manufacturing requirements, no one can afford to be non operational for any significant period of time. If the supplier is not able or available to help get the system up and running again, this can lead to costly hours of non-production. 

It’s not surprising that many of our own decisions in everyday life - for example what car we choose - can often come down to the level and quality of support we get from the supplier or dealerships we encounter.

On occasion, a driver for change can come from external sources.  New regulations in safety requirements may make a change mandatory by a specific date.  Or the competition may have already invested in more modern systems making their production more efficient with resulting lower cost products.

In summary, there are a number of issues and reasons that can influence a business to consider a change of control system.  However, in all cases there is one common issue that affects them all.  Whenever businesses change, there is an associated risk.  The most significant one is lost production and potentially lost customers. 

Whichever reason is used for changing over a control system it must be carried out by vendors who can demonstrate a clear understanding of the processes involved and who have the skills to be able to do this with minimal disruption to the day-to-day requirements of the business.