Ovation PID parameters explained
Ovation uses gain for proportional action and seconds per repeat for reset. A time-per-repeat convention means a lower number is faster integral action — the same direction as DeltaV, though Ovation counts in seconds rather than minutes.
The seconds rather than minutes is the detail to watch when converting a tuning set from a minutes-based system. A reset that reads as 15 on one system and as 0.25 on the other can be the same loop expressed in different units, and a factor of sixty in the wrong direction changes a stable loop into a hunting one.
Which direction makes the action stronger
On your system a HIGHER proportional number means MORE aggressive proportional action.
Reset is in seconds/repeat, so a LOWER number means FASTER integral action.
This is the single most consequential thing to get right. Proportional band and gain move in opposite directions, and so do repeats-per-time and time-per-repeat. An engineer who has moved from one system to another and carried the old habit across will make loops worse while believing they are improving them.
- Proportional term: gain
- Reset units: seconds/repeat
- Rate units: seconds
- Algorithm form: ideal noninteracting
Converting to and from other systems
Converting reset between seconds per repeat and repeats per minute is a reciprocal within the minute: a loop with a reset of 15 seconds per repeat repeats four times per minute, so the two numbers multiply to sixty.
Because it is a reciprocal, the error you make by getting it backwards is not a constant factor. It grows as the numbers move away from one, which is why the mistake is sometimes survivable and sometimes catastrophic.
Why the algorithm form matters
The algorithm form matters because the same three numbers behave differently in each. In the series (interacting) form the derivative term multiplies the proportional-plus-integral term, so changing rate also changes the effective gain and reset. In the ideal (non-interacting) form the three terms are independent of each other but all scaled by gain. In the parallel (independent) form even that scaling is absent — gain does not affect integral or derivative action at all. Moving a tuning set between systems without converting for form is one of the commonest ways a loop that worked on one plant fails on another.
Before you change anything
Confirm the units on the actual controller rather than trusting the platform default. Systems get configured in unusual ways, engineering units get changed during a migration, and a controller imported from another site may carry conventions from there.
The fastest check is to make a small deliberate change and watch which way the loop responds. If it gets more aggressive when you expected less, the convention is not what you assumed.
Questions that come up
What does seconds per repeat actually mean?
It is how long the integral action takes to repeat the correction the proportional term has already made. A reset of 15 seconds means that if the proportional term is contributing a certain amount of output, integral action adds that same amount again every 15 seconds while the error persists, so it repeats four times in a minute.
Related
Last reviewed 2026-09-11.