salmson LRE Serie Instalacion Y Puesta En Servicio página 108

English
98
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 "Tab. 3: Connection terminal
assignment" on page 80.
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.
These parameters should only be changed in small increments, and
the effects on the system should be monitored continuously. Param-
eter values should only be tuned by someone with training in control
technology.
Controller Factory setting Setting range
term
P 0.5
I 0.5 s
D 0 s
(= deactivated)
Tab. 8: PID parameter
The direction of action of the controller is determined by the sign of
the P term.
Positive PID control (default):
If the sign of the P term is positive and the process value drops below
the setpoint, the control will increase the pump speed until the set-
point has been reached.
Negative PID control:
If the sign of the P term is negative and the process value drops below
the setpoint, the control will decrease the pump speed until the set-
point has been reached.
NOTE:
Check the controller's direction of action if PID control is being used,
but the pump is only running at minimum or maximum speed without
responding to changes in the parameter values.
Increment
-30.0 ... -2.0 0.1
-1.99 ... -0.01 0.01
0.00 ... 1.99 0.01
2.0 ... 30.0 0.1
10 ms ... 990 ms 10 ms
1 s ... 300 s 1 s
0 ms ... 990 ms 10 ms
1 s ... 300 s 1 s
Salmson 11/2017