20
GOSSEN METRAWATT GMBH
–
dbnd
=
0
Setting for 3-step and step-action controllers
–
Activate the actuators with
automatic operation
, and start the recorder if applicable. Record several
oscillations until they become uniform in size.
–
Measure
oscillation amplitude x
ss
.
–
Record
on-time T
I
and
off-time T
II
at switching output I for the oscillations.
Evaluating the Oscillation Test
1
) If either T
I
or T
II
is significantly greater than the other, value
tu
is too large.
Correction for step-action controllers in the event that T
I
or T
II
is smaller than
tY
:
tY
•
tY
tY
•
tY
Multiply
Pb 1
by ,
if T
I
is smaller, or by
, if T
II
is smaller.
T
I
•
T
I
T
II
•
T
II
The value for
tu
is very inaccurate in this case. It should be optimized in the closed loop control mode.
Closed Loop Control Mode
The closed loop control mode is started after self-tuning has been completed:
–
Configure the desired control algorithm with
controller sort
.
–
Adjust the
setpoint
to the required value.
–
The dead band can be increased from
dbnd
=
0
for 3-step and step-action controllers if control of switching
output I and II changes too rapidly, for example due to an unsteady actual value.
Parameter Values
tu
1)
0,3
•
(T
I
+ T
II
)
0,2
•
(T
I
+ T
II
– 2
tY
)
tc
tu
/ 12
tY
/ 100
Pb 1
x
ss
•
100 %
MRS
x
ss
•
T
II
•
100 %
MRS (T
I
+ T
II
)
x
ss
•
50 %
MRS
Pb11
–
Pb 1
•
(T
I
/ T
II
)
–
Parameter
2-step controller
3-step controller
Step-action controller
T
I
T
II
x
ss
