GE Mark VIe PID parameters explained
GE's Mark VIe controllers execute their loops in the function-block library of the Data Control Module, and the tuning constants appear as a proportional gain with integral and derivative time in seconds.
The gain-and-seconds convention keeps the direction of a change the same as most modern systems: higher gain is more aggressive, higher integral time is slower. The constraints that dominate on turbine control are often outside the PID itself, which is worth remembering before the constants are blamed.
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
What is often the limiting factor
On turbine and generator control the loop is usually fast and well instrumented, and the limit is more often the actuator, the output rate limits or the speed-sensing path than the PID terms themselves. A loop that will not stabilise deserves a structural check before its tuning is rewritten.
Output rate limits in particular behave like an extra lag. Tuning that assumes an unrestricted output will fight them, and no amount of gain recovers a delay imposed by the controller's own limits.
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
Is GE reset in seconds or minutes?
Seconds is the common configuration. Confirm on the actual block, because the same number in minutes is sixty times slower and the two look identical on paper.
Does a higher GE gain mean faster action?
Yes — gain is the correction per unit of error, so a higher number is more aggressive.
Related
Last reviewed 2026-08-01.