Re: [foxboro] Some things to talk about

=20Hi David,

=20 You might look at nonlinear zone control on your PIDA blocks.  I have=

several slurry sumps that I set up with a +/- 3 inch zone around the
setpoint where the tuning is ten time slower.  If the level gets outside
the "dead zone" the controller quickly ramps the pump speed up or down
to get back.

Steve Murray
Asarco

*******************
* From FoxDoc *
*******************
Nonlinear Option (NONLOP) allows you to change the gain in a zone about
zero error. The zone is defined by HZONE and LZONE, and the gain by
KZONE



-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Nimmons, David
Sent: Thursday, July 24, 2008 1:25 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Some things to talk about

How about adding an Integral deadband to PIDA blocks, so that when the
process is within the deadband, the Integral action is turned off. We
have many loops within our plant where the controller cannot control
right on setpoint, so, there is a constant small swing around the
setpoint, with the controller output having a sawtooth pattern. An
Integral deadband would help eliminate that.

David Nimmons

=20
=20
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