More Bypass Surgery…

“We are supposed to be generating at max, with heater six bypassed, but we had a run-back and now we can’t set the target load up to where it should be!”

Early one morning, just as I was passing through the main gate at a client’s power station site, I heard the familiar sounds associated with operation of the turbine bypass system on the nearest generating unit.  Given that I was at the site to conduct the first stage of a power plant simulator training programme for two newly appointed trainee operators, I thought that this latest event might be another useful topic for our training activities.

My first opportunity to visit the plant control room came during the lunch break and, while walking through the basement level of the plant, I noted the tell-tale signs that the Unit’s Final HP Heater was in a bypassed state. 

When I entered the control room, both of the unit controllers were hunched over the Unit 1 control panel, and were engaged in what appeared to be serious conversation (obviously, Unit 2 was operating normally and not presenting any issues that required attention).

As I approached the Unit 1 control desk, and announced myself with a cordial “hello gentlemen”, the operator in charge of the unit, looking somewhat frazzled and pleading, greeted me with a question which I normally would not expect from anyone in his position: 

“Mate, I hope you can help us.  We are supposed to be generating at max, with heater six bypassed, but we had a run-back and now we can’t set the target load up to where it should be!  System [Network System Control] isn’t happy, and wants us up there ASAP.  What’s stopping me from setting it?”

I had known both of the operators for many years, and had come to regard them as appearing to be reasonably competent, conscientious and diligent operators, and that they had always been amicable and helpful people.  But I did not expect either of them to be confounded by the situation which they had been confronting since early morning.

While it was very clear to me what the problem was (confirmed by the illuminated HP Heater Bypass alarm tile on the panel), I reminded myself that anyone and everyone can suffer lapses of memory from time-to-time, and more so when under pressure.  I was also acutely aware that, as an outsider and a contractor, it was important for me to exercise caution and a high degree of diplomacy.

Accordingly, I decided that the best strategy would be to try and help them to remember something that they surely did know, but simply couldn’t recall in the moment.  I really felt that this would be a better approach than pointing out what had been done wrong, what should have been done, and what should be done now.  “How did you take HP six out of service?”, I asked, quietly and earnestly. 

“Well, when I got the order [from the System Control operator], I bypassed heater six and then went to raise the target load, but the unit was unloading and I wasn’t able to push it back up… still can’t!”. 

Obviously, they still hadn’t clicked, and I would need to persevere.  I also reminded myself about the nature of the training philosophy and approach which had existed at this site, over many years, and which I had long regarded as being patently ill-founded and substantively ineffective.

“Remember that there are two ways to bypass the heater,” I offered, and waited for the penny to drop.  But it didn’t, and they were both staring at me, blankly.  So I continued, quietly and earnestly, as before:  “Overload operation requires that the heater be taken out-of-service in a controlled manner – not using the Heater Bypass Trip, which is a plant protection measure,” I said, while also pointing briefly to the tell-tale alarm tile.

The silence, and the blank stares, remained, so I got to the point:  “If you use the Heater Bypass Trip pushbutton, then you are activating the plant protection function, and this in-turn initiates a Unit Run-back.  The load-down is lead by the Load Limiter, and is held until the trip condition is reset.” 

They both nodded, and I hoped that this indicated their understanding and agreement.  Sadly, neither person acknowledged that they actually knew about this, which only served to raise my level of concern. 

Throwing diplomacy to the wind, I carefully explained what they needed to do, and how (including a cautionary reminder that, with this type of HP Heater Bypass Valve configuration, they would need to first isolate the heater properly, before resetting the Bypass Trip).  They both acknowledged that they now understood at least that much, and that they were very grateful for my advice. 

However, I resolved to ensure that we would later discuss at least two key issues associated with this event:  Firstly, the rationale for a heater bypass trip-initiated unit run-back and, secondly, the need to use the heater bypass valve blocking devices before resetting the heater bypass trip condition.

Later in the day, I was happy (and relieved), to hear that they had finally managed to achieve target load.  Trying hard not to think about the cost of lost generation associated with this event, the experience reminded me that not everyone enjoys the benefit of comprehensive training, whether that training be in a formal setting or on-the-job.  It also reminded me that, even when training is provided, there is often only a small proportion of knowledge that is actually remembered.

In my experience, subjects that are thoroughly explained and discussed (and, if possible, also demonstrated and practiced – as the plant simulator offered), will be understood and remembered.  I believe that this is a fundamental factor in all learning, and that it is also a vital factor in human abilities and performance. 

A person gains pride and confidence with growing knowledge, understanding, personal application and demonstrated competence.  As a community, we can all benefit from helping each other, and the Forum has been created specifically to advance this goal.

M. Cogitari

[Note that this conversation relates to a particular type of power plant, and that specific plant and control details may not be applicable at other sites.  The opinions expressed in this article are those of the author, and are not necessarily shared by the Forum].