EXPERIMENT ( LAB 1 )

Course Code : JM507
Course          : Control System
Program        : DEM

LEVEL CONTROL DEMONSTRATION PANEL

Control technology is now an integral part of nearly all areas of engineering. Accordingly, a description of its basic principles is a standard feature of technical training programs.

The demonstration models of the RT-6x4 series from G.U.N.T. make it possible to ascertain relationships between control parameters in practical experiments and demonstrate these relationships so that they are clear and easily memorizable.

Every model comprises a fully functional system of processes with its own control circuit. An extensive use of modern industrial components makes the models as realistic as possible. As the students, we thus not only obtain knowledge of basic control principles but also an overview of the control elements's design, functionality and application.

The models have a desktop design and require very little maintenance. They are ideal as training aids for laboratory experiments at technical colleges and universities and intended exclusively for educational purposes.

1. Devices description

• The RT 614 demonstration model is a desktop device to control filling levels.
• Water is used as the operating medium here. Filling levels are controlled by an electronic industrial unit which can be configured as a P.PI or PID controller.
• Experiments with the demonstration model involve modification and adaption to system control parameters.

2. Device layout

• The RT 614 demonstration model for filling level control has following layout:

3. Process scheme

4. The controller 

• The digital universal controller is equipped with a microprocessor with digitally processes input signals and converts them back to analog variable prior to output.

5. Question

• Draw block diagram for the control system
• Explain the system base on each block diagram?
• Draw a conclusion base on the system?

Solution

• Draw block diagram for the control system

• Explain the system base on each block diagram?

Reference Input (setpoint)

-The reference point is an external signal applied to the summing point of the control system to cause the plant to produce a specified action. This signal represents the desired value of a controlled variable and is also called the “setpoint.”

Actuating Signal

-The actuating signal represents the control action of the control loop and is equal to the algebraic sum of the reference input signal and feedback signal. This is also called the “error signal.”

Control Element

-The control elements are components needed to generate the appropriate control signal applied to the plant. These elements are also called the “controller.”

Manipulated Variable

-The manipulated variable is the variable of the process acted upon to maintain the plant output (controlled variable) at the desired value.

Disturbance

-The disturbance is an undesirable input signal that upsets the value of the controlled output of the plant.

Plant

-The plant is the system or process through which a particular quantity or condition is controlled. This is also called the controlled system.

Controlled variable (output)

-The controlled output is the quantity or condition of the plant which is controlled. This signal represents the controlled variable.

Feedback Element

-The feedback elements are components needed to identify the functional relationship between the feedback signal and the controlled output.

Feedback Signal

-The feedback signal is a function of the output signal. It is sent to the summing point and algebraically added to the reference input signal to obtain the actuating signal.

• Draw a conclusion base on the system?

A block diagram of a system is a pictorial representation of the functions performed by each component and of the flow of signals. In a block diagram all system variables are linked to each other through functional blocks. The functional block or simply block is a symbol for the mathematical operation on the input signal to the block that produces the output.

Figure 1.1 shows an element of the block diagram. Such arrows are referred to as signals.

Figure 1.1      Element of a block diagram

(Source : Katsuhiko Ogata (1990), Modern Control Engineering)

The advantages of the block diagram representation of a system lies in the fact that it is easy to form the overall block diagram for the entire system by merely connecting the blocks of the components according to the signal flow and that it is possible to evaluate the contribution of each component to the overall performance of the system.