Sabio 2010D, Operation Manual

Page: 168 / 182

Internal UV Ozone Photometer Page 9-18
Derivative Term Constant
The Derivative constant is multiplied by
the integral term of the PID equation.
The derivative term represents the
current rate-of-change of the error.
The derivative term is normally small or
zero.
PID Filter
The PID Filter smoothes the Photometer's
measurements prior to the PID equation.
This
is necessary since excessive
Photometer noise can cause the PID loop
to attempt to compensate for variations
that are merely cause by noise. The
value entered for the PID Filter is the
number of photometer cycles to use as
the filter's time constant.
Filter Holdoff
This is the number of photometer cycles
to wait after a change in the ozone
setpoint
before beginning the PID
filter.
PID Holdoff
This is the number of photometer cycles
to wait after a change in the ozone
setpoint before activating the PID servo
control. This is normally set such that
the Photometer's natural response to an
ozone change has stabilized before the
PID
loop is activated for final
adjustments.