Emerson Tescom ER5000 Series User Manual page 38

ER5000 — How It Works
Table 1 gives a summary of the rules of thumb for Proportional,
Integral and Derivative.
Table 1: Effect of P, I and D Increases on Response Curve of Controller
Increased
P Value
Rise Time Faster
Instability More
(Overshoot/Ringing)
Settling Time Varies
Offset Less
* Excess D Value can, however, result in more instability rather than less. Refer to
the restatement of the rules of thumb for Derivative on
The ERTune program gives you a rich visual environment and
™
precise, intuitive controls for tuning the ER5000. Refer to
Tuning Tab: Controls and Functions for Tuning the ER5000
for a detailed explanation of the program's capabilities and
features, as well as tips and techniques to achieve optimal
system performance.
Increased Increased
I Value D Value
Faster Slower
More Less*
Longer Shorter
Eliminate Varies
page 37.
The
Every system has unique characteristics, every operational
environment presents unique challenges and every application
has unique requirements. Optimal tuning will invariably involve
both trial and error and compromise. Fast rise time usually comes
at the expense of increased instability. Minimizing overshoot may
result in response lag or offset. Eliminating offset may introduce
unwanted windup. It is important to know your priorities and
understand the trade-offs.
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