English
82
WILO SE 05/2010
9.4
Setting the control mode
p-c/p-v control:
NOTE:
Alternatively, manual control mode (Fig. 37) or PID operating mode
can also be set.
Manual control mode:
“Manual control” mode deactivates all other control modes. The
speed of the pump is kept to a constant value and set using the rotary
knob.
The speed range is dependent on the motor.
PID controller
The PID controller in the pump is a standard PID controller, as
described in control engineering literature. The controller compares a
measured process value to a predefined setpoint and attempts to
adjust the process value to match the setpoint as closely as possible.
Provided appropriate sensors are used, a variety of control systems
(including pressure, differential pressure, temperature and flow con-
trol) can be realised. When selecting a sensor, keep in mind the elec-
trical values presented in the table titled “Connection terminal
allocation” on page 65.
The control behaviour can be optimised by adjusting the P, I and D
parameters. The P (or proportional) term of the controller contributes
a linear gain of the deviation between the process (actual) value and
the setpoint to the controller output. The sign of the P term deter-
mines the controller's direction of action.
The I (or integral) term of the controller provides integral control
based on the system deviation. A constant deviation results in a linear
increase at the controller output. Hence a continuous system devia-
tion is avoided.
The D (or derivative) term responds directly to the rate of change of
the system deviation. This affects the rate at which the system
responds. In the factory settings, the D term is set to zero, since this
is an appropriate setting for a number of applications.
Fig. 36:
p-c/
p-v
control
Q
s
H
m
a
x
H
H
s
H
min
H
s
1
2
Q
H
H
Q
H
m
a
x
H
s
H
min
H
s
1
2
Setting (Fig. 36) p-c
p-v
Duty point on
maximum pump
curve
Starting at the duty
point, draw towards the
left. Read off setpoint
H
S
and set the pump to
this value.
Starting at the duty
point, draw towards the
left. Read off setpoint
H
S
and set the pump to
this value.
Duty point
within the con-
trol range
Starting at the duty
point, draw towards the
left. Read off setpoint
H
S
and set the pump to
this value.
Move to max. pump
curve along control
curve, then horizontally
to the left, read off set-
point H
S
and set the
pump to this value.
Setting range
H
min
, H
max
see pump curves
(in catalogue, select or
online)
H
min
, H
max
see pump curves
(in catalogue, select or
online)
1
2
Fig. 37: Manual control mode
Q
H
H
Q
n
min
n
max
s
H
s