What do you know about Digital Control System error prevention?

For those sending in HU questions, I really appreciate the opportunity to give you some answers and open it up to our readers for even more input. You never know where this may lead. I will keep the question and answer sources confidential, but I will make sure any replies or suggestions get back to you. Onward with more Q&A:

Question#2

Hi James,

Just wanted to see if you had any advice for reducing error in control rooms – specifically regarding Digital Control Systems…  It’s pretty easy to remind an operator in one of our old Coal sites that still have bench board controls to use Self Check – but our Gas sites are almost all purely digital control, and we are having lots of HU errors around taking off a piece of critical equipment on the wrong unit.

Our long term plan is an engineering barrier (moving to separate screen set up for each unit) but that is going to be very costly across the fleet, and we need something to help them focus until there are budget dollars to finish the project.  Any suggestions?

Answer#2

I could use some more context surrounding the types of errors made, but I will give this a try: Since it's potentially not as stringent as nuclear, perhaps a checklist would be helpful for operators to follow? Like all other HPI professionals, I am a proponent of an engineered barrier before all others - I am glad your team is pursuing a solution towards that end. How about forcing a concurrent verification prior to taking a critical piece of equipment offline? The second verifier only needs to be present during the critical step, and then can go do other things.

What are some corrective actions you've taken in the past that do not seem to be working now?

What exactly do your operators value? Doing it correctly, or getting multiple things performed on a shift? Are the operators overloaded with tasks? What are the distractions that have to be managed on a daily basis, or at least when these mistakes happen?

This may be a function of too much production pressure and not enough prevention. (Thanks James Reason)

Some personal OE (operating experience):

I remember as an Instrument and Control Technician when an Engineer was first briefing me on the Foxboro Digital (editor note: maybe it was called "Distributive" but was still digital) Controls System when I went to point to something on the screen he literally slapped my hand away and said, "DON'T TOUCH!" In that instant he instilled in me that it is better to look with your eyes than your hands when dealing with touch screen controls. It was quite a surprise, which I would rather experience than accidentally moving a valve's position in the plant. (Thanks Johnny)

I really appreciate the question - do any readers have a suggestion or an edit to mine? Please feel encouraged to comment, either here or by email.

[From the author: Thanks to Adrian for suggesting the Q&A section on this blog]