ControlMaster CM30, CM50 and CMF310
Universal process controllers,
1
/
4
,
1
/
2
DIN and fieldmount
7 Advanced Level
IM/CM/ED–EN Rev. X
51
…Control / …Loop 1 (2) Control / …Gain Scheduling
Mode
Turns the gain scheduling function
On
or
Off
.
S
ource
The
Gain Scheduling
(GSRef) reference signal – see Appendix A, page 104 for description of
sources.
Limit 1 (2)
Limit 1
– sets the point where the gain scheduler switches between the first and second sets
of
PID
parameters.
Limit 2
– sets the point where the gain scheduler switches between the second and third
sets of
PID
parameters
Reset
If the gain scheduler is reset, the next time
Autotune
(see page 29) is used all 3 sets of the
PID
parameters are set – see page 30.
FeedForward
FeedForward
can be used to eliminate disturbances that can be measured before they affect the process variable.
Feedforward
Adaptive Gain
or
Static Gain
can be used to eliminate these measurable disturbances – see below.
Note
.
FeedForward
is enabled only if a FeedForward application template is enabled – see Section 8, page 88 for
template options.
Calculating Static Gain
If the parameter mode is set to
Static Gain
(see page 52) the gain value can be determined using the following
procedure:
1 Disable
the
FeedForward
function by setting
Mode
to
Off
– see page 52.
2
Bring the system to a steady state.
3
Take note of the values of the disturbance variable (see DV, above) and the Controller output (identify them as v1
and u1 respectively).
4
Introduce a process disturbance, for example, by changing the process load, and then wait until the system is in a
steady state.
5 Take note of the values of the
Disturbance Variable
and the Controller output (identify them as v2 and u2
respectively).
6
Use the following formula below to calculate the value of the
Static Gain
parameter:
7 Enable the
FeedForward
function by setting
Mode
to
Static Gain –
see page
PV
FeedForward
Process
SPT
PID
Disturbance Variable (DV)
U
PID
U
FF
= DV x Gain
Controller O/P
U = U
PID
+ U
FF
= U
1
U
2
V
1
V
2
Gain
