Select Page

Asset and maintenance management has entered into an era where technology is employed to operate other technology in order to keep facilities operating. A scary thought for some and yet it is a fact of life that is not going away.

To help you understand how technology is playing a key role in many facilities, we have a guest article today by Don Fitchett, President of Business Industrial Network (BIN)

PLC Safety and Reliability Guest Post – by Don Fitchett

I’ll give you a clue; it has the letters PLC in it. Yes, you probably guessed what it is by now, the Programmable Logic Controller. And even more so is the next technological advancement to the PLC, the Process Automation Controller (PAC), but I‘ll talk about that a little later. It is not the PLC it’s self that is the problem as they are highly reliable devices, it is how we work with PLCs that makes our systems so much less reliable.

The PLC controls just about every machine, in every industry, in every country, yet is the last item that plant maintenance and engineering do reliability analysis on. If the reliability issues related to PLCs are even addressed at all. What is even more surprising and even less known, is that the PLC also controls most of the world’s infrastructure. The PLC controls most of the world’s power, water, traffic lights, trains, elevators, big building’s HVAC and much less critical equipment like boilers, bridges, tunnels, hospital incinerators, combines, car crushers, etc.

Better safety and reliability in your car than in your machine…

The PLC is like your cars “Brain Box” or Electronic Control Unit (ECU), in the respect that it is an out sight-out of mind little black box, until the car breaks down. The difference being when your car’s ECU indicates a problem, you have a technician trained and certified on that unit work with it. When a machine or other PLC controlled system indicates a problem, most have an electrician or engineer with little training on that specific PLC work on it. There are other differences too. An ECU typically affects one piece of equipment that typically cost less than $40k. A PLC typically affects one or many machines, each costing $100k to millions of dollars. But more importantly an ECU affects the reliability of one machine (car) and the safety of one person. A PLC can affect the reliability and safety of many machines and many people.

So, how is safety and reliability put at risk when working with PLCs?

  • Lack of training
  • Lack of policies and procedures
  • Complacency
  • Lack of security

The above four causes of safety and reliability risks associated with PLCs are in order of importance. The number one cause of risk while working with a PLC, is lack of proper training. Because technology in manufacturing and other related industries evolve almost as quickly as the computer industry, text book training alone is not enough to qualify an individual to work with PLCs. (Especially since the textbooks are out of date by the time they get printed anyway.) But more importantly, safety and reliability policies and procedures must be incorporated in to the training. These safety and reliability procedures must also be incorporated into company policy. Company policy must dictate only those “properly trained” be allowed to work with the PLCs and that each year employees be retrained and qualified to avoid complacency and keep up with technology advancements. With PLCs, lack of security was a rare cause of safety and reliability risk in the past. But with more networking of PLCs to other devices the risk has been steadily increasing. With the evolution of the newest controller, the PAC, the risk is climbing exponentially.

Safety and reliability get worse with new technology …

With PLCs, all four categories of risk to safety and reliability have been greatly increased. Mostly due to the fact it is new technology and lack of training. But equally so because of the way the PLC is designed. The PLC is designed to mimic electrical circuits and for the electrician to work with. The PLC is designed to combine the PLC with motion control and other technologies, including computer programming. Companies are hard pressed to find electricians who also have a degree in computer programming, or computer programmers who also know PLCs.

Complacency is not really an issue with the relatively new PLC, as most find it over complex and confusing. But security greatly increases because of the ever growing use of Ethernet and even the Internet to access PLCs. Maintenance and engineering are not as likely to know and take computer communication security steps and procedures. As IT personnel are not as likely to understand the concept and reality that a PLC on their network breached, is not as simple as just backing up the program. Breaches in PLC/PLC security don’t just crash a program; they can crash a machine causing damage to real world man or machine!

Oh the stories I can tell.

So my advice to companies, get annual PLC training that includes safety and reliability. Just as importantly, get policy and procedures that include PLCs/PLCs.

I would also highly recommend you read the article Managing PLCs in your Facility.

About the Author:

Don Fitchett is President of Business Industrial Network (BIN), an industrial training company specializing in PLC training. Don has held that position for over 15 years and has been in the industrial training industry for over 25 years.