There were things I didn't like about Ovation. Also, at that time, they didn't have MPC, fuzzy, and NN bundled on the system. The processes needed those algorithms to get the gains we wanted and we couldn't wait for Westinghouse/EPM to develop them on the Ovation platform. It's also based on SAMA, which is a dead standard, to my knowledge. Its foundation is more for the power industry than process and we were process. At that time, the graphics were not as good as the DeltaV's graphics. I don't know what either look like now. The configuration environment on the Ovation was not as good as the DeltaV's. DeltaV seemed much better "thought out" than Ovation, to me.
There were other reasons, too, but they escape me as that's been several years ago. My main programmer didn't think it was suitable either and was lacking compared to the DeltaV. He had almost 40 years of programming experience from OS to process control. He didn't know everything but he knew quite a bit and was a level headed thinker.
One of my former colleagues has been working with Ovation for about a year. He has over 30 years of systems experience on Provox and DeltaV. His recent opinion is that DeltaV is much better than Ovation. Ovation is OK but it is not a DeltaV. I've not had an opportunity to get specifics from him but fully intend to.
It was nothing personal it just didn't fit what I wanted and what I thought the plant needed. I went to grad school with one of the Ovation guys and know its got great people behind it. My friend is much, much more intelligent and educated than me. I trust him implicitly with all things. I've met some of the other Ovation guys, who were equally impressive.
There was a big battle between the Ovation guys and DeltaV guys back then to get my business. EPM finally mandated Ovation for power and W/WW and DeltaV for process. That significantly reduced my headaches with my own internal folks, i.e., managers, who didn't have much DCS experience thus knowledge on how to assess them. I don't know if EPM still has that edict or not but they did many years ago.
I was a corporate engineer in those days, with plants spread across North America. We had a smattering of Provox and Westinghouse systems. They were all being phased out so we, I, had to make a decision. I wanted uniformity for a host of reasons.
Systems are not a "one size fits all" game. At least, they are not in my experience. You have to know the processes and what needs to be done to realize gains with a new system. Then you need the ability to discern which system fits. That also encompasses the abilities of operations and maintenance.