Description:
The difference serves as a basis for characterizing processes. It is important to know the behavior of the process for correct implementation of the PCS 7 PID tuner.

Non-self-regulating processes:
These are processes with integrating characteristics.

Self-regulating processes:
These are processes without an integrating characteristics.
To test a process for its characteristics, with an open control loop you can either give an input jump to the system or an input pulse. The time behavior is recorded and analyzed to determine the process.

Jump:
In the case of a jump, for example, the position of the inlet valve of a container is changed from 0% to 15% OPEN and remains in that position.

Pulse:
In the case of a pulse, the setting of the valve is also changed from 0% to 15% OPEN, but only for one minute, for example. The valve is then set back to 0% again.

Depending on the system and type of trigger, there are different reactions. From the reactions of the process, you can determine whether you are dealing with a process with or without self-regulation.

The difference is explained below according to the system triggering and illustrated by an example.

Example of a pulse-type triggering of the process:
The process is triggered by a pulse. For this you change the value of the actuator [LMN output on the CTRL_PID]. Depending on the type of process, the valve position or the motor speed is changed for a specific time, for example.
Depending on the process, there can now be various reactions [input PV_IN at CTRL_PID].
If the signal here takes the form of the two curves of Cases 1 and 2 in the next figure, then you have a system with self-regulation.
The trends of Cases 3 and 4 characterize a process without self-regulation.

The figure shows the reaction to pulse-type triggering of the process.

Fig. 01

a) The example is of a tank that is heated by a heat exchanger.
The actuator is the valve and the control value is the temperature.
If a pulse is given to the actuator, the temperature rises in the tank.
When the valve is closed, the temperature falls again to the ambient level.
This happens because the heat energy is given off to the environment. In other words, there is "regulation".
So this is a process with self-regulation.

The figure shows a process with self-regulation and the reaction to a pulse-type triggering.

Fig. 02

b) In this example we have a tank with an inlet valve. The actuator is the valve and the control value is the tank level.
If the valve is now opened, the level of the tank rises. When the valve closes, however, the tank level does not sink, but remains constant. In other words, there is no "regulation" as in the previous example.
This therefore is a process without self-regulation.
The figure shows a process without self-regulation and the reaction to a pulse-type triggering.

Fig. 03

Example of a jump-type triggering of the process:
The process is triggered by a jump. For this you change the value of the actuator [LMN output on the CTRL_PID]. Depending on the type of process, the valve position or the motor speed is changed, for example.
Depending on the process, there can now be various reactions [input PV_IN at CTRL_PID].
If the signal here takes the form of the two curves of Cases 1 and 2 in the next figure, then you have a system with self-regulation.
The trends of Cases 3 and 4 characterize a system without self-regulation.

The figure shows the reaction to jump-type triggering of the process.

Fig. 04

a) The example is of a tank that is heated by a heat exchanger.
The actuator is the valve and the control value is the temperature.
If a jump is given to the actuator, the temperature rises in the tank.
After a certain transition time, a new temperature level is reached in the tank.
This happens through loss of heat to the environment, there is therefore "regulation".
So this is a process with self-regulation.
The figure shows a process with self-regulation and the reaction to a jump-type triggering.

Fig. 05

b) In this example we have a tank with an inlet valve. The actuator is the valve and the control value is the tank level.
If the valve is now opened, the level of the tank rises. The level continues to rise constantly through the inlet medium until the physical limits of the system are reached (in this case the maximum level of the tank). In other words, there is no "regulation" as in the previous example.
This therefore is a process without self-regulation.
The figure shows a process without self-regulation and the reaction to a jump-type triggering.

Fig. 06

Keywords:
Integral behavior, PID self-tuner, Control loop optimization, Control loop parameterization