- Joined
- Jun 18, 2011
- Messages
- 6,479
- Reaction score
- 392
Well ... yeah ... but not constantly changing - like in an autopilot, or in a steel-rolling mill where quenching might takes place intermittently, or in a high-speed paper web (think newspaper printing machines), where sudden step changes in error - and in the rate of change in error- can be real buggers to control.
But I think we essentially agree - although is achieving set-point rapidly without overshoot really a priority here ?
In my experience, the main problem with the use of PID controllers is not with the controllers themselves, but rather with the people who want to use them - for there is so often an expectation that they can work miracles.
Even in an inherently unstable system, it is so often expected that just hooking-up an expensive wizzo device (at least they used to be expensive - my guess is that the Eurotherm 810's that I used to use still are ...) will instantly be able to control anything - and of course, that's just so much cobblers.
The really important thing which is so often overlooked in applications such as this, is to keep the thermal transfer medium well stirred - just the simple investment in a small fan to keep the warm air circulating will improve temperature control significantly.
LJ
This is a lump of a honey, a uniform viscous liquid, nothing thermally weird or challenging apart from the insects made it. However thermal overshoot will impair its quality and increase the HMF. The Pid we have here gets regularly swapped between a 60W heater in 0.75m3 seed incubator and a 48w heater heating up a 75mmx25mm piece of ally with no fiddling by the beekeeper /gardner/bontanist operator , who has remarked on the better germination she gets and the ease of use of the staining material (btw we also have a Eurotherm 91e) Since my views here are in the minority I will leave you to your state of the ark bi-metallic strips.
Last edited: