Manual Tuning; Multiset Function,Set Gradient; Twin Setpoint Application (Ramp + Hold + Time Expiration Alarm) - gefran 1200 Bedienungsanleitung

Influence of Proportional, Derivative and Integral actions on response of process under control
* An increase in P.B. reduces oscillations but increases deviation.
* A reduction in P.B. reduces the deviation but provokes oscillations of the controlled variable (the system tends to
be unstable if P.B. value is too low).
* An increase in Derivative Action corresponds to an increase in Derivative Time, reduces deviation and prevents
oscillation up to a critical value of Derivative Time, beyond which deviation increases and prolonged oscillations
occur.
* An increase in Integral Action corresponds to a reduction in Integral Time, and tends to eliminate deviation between
the controlled variable and the setpoint when the system is running at rated speed.
If the Integral Time value is too long (Weak integral action), deviation between the controlled variable and the set-
point may persist.
Contact GEFRAN for more information on control actions.

Manual Tuning

A) Enter the setpoint at its working value.
B) Set the proportional band at 0.1% (with on-off type setting).
C) Switch to automatic and observe the behavior of the variable. It will be similar to that in the figure:
D) The PID parameters are calculated s follows: Proportional band
Process
Variable
Peak
Multiset function, Set gradient
SP
SP2
SP1
SPrem
ON
IN1
LOC/REM ON
(*) if the set gradient is set
Twin setpoint application
(ramp + hold + time expiration alarm)
P.B.= ---------------------------------------- x 100
T
(V max - V min) is the scale range.
Integral time: It = 1.5 x T
Derivative time: dt = It/4
E) Switch the unit to manual, set the calculated parameters. Return
to PID action by setting the appropriate relay output cycle time,
and switch back to Automatic.
F) If possible, to optimize parameters, change the setpoint and
Time
check temporary response. If an oscillation persists, increase the
proportional band. If the response is too slow, reduce it.
The multiset function is enabled in hd.1.
The gradient function is always enabled.
You can select between setpoint 1 and setpoint 2 with the faceplate
key or with digital input.
You can display the setpoint 1-2 selection by means of LED.
SP1
(*)
SET GRADIENT: if set to ≠0, the setpoint is assumed equal to PV at
t
power-on and auto/man switchover. With gradient set, it reaches
the local setpoint or the one selected.
Every variation in setpoint is subject to a gradient.
t
The set gradient is inhibited at power-on when self-tuning is engaged.
If the set gradient is set to ≠0, it is active even with variations of the
t
local setpoint, settable only on the relative SP menu.
The control setpoint reaches the set value at the speed defined by
the gradient.
Peak
(V max - V min)
AL
Absolute alarm
Setpoint profile
Referred to current
setpoint
Reverse alarm
Direct alarm
72
Time (min. or sec.)
(*) Time set in
parameter Hy.n