DESCRIPTION:
The setup consists of a process tank fitted with scale in which water enters through a Pneumatic control valve. Water is pumped to process tank from the sump tank by means of a centrifugal pump. The level transmitter is fitted in the process tank. The level of water in process tank is sensed by the transmitter and communicated to the digital indicating controller. This measured variable is compared with the Set Point by controller and output is generated and given to I/P converter, which in turn supply the 3-15 Psig pressure to vary the opening of the Pneumatic control valve to eliminate the error observed. As the opening of pneumatic control valve varies, the level in the Process Tank gets effected. This process goes on until the Set Point target is achieved. A ball valve is also provided in the process tank to disturb the system and to observe the effect of disturbance. The drain and overflow of the process tanks returns in the sump tank, hence the system operates in close circuit. These units along with necessary piping are supported in a well-designed housing and are fixed on base plate. The process parameter is controlled through Computer by micro-processor Controller (SCADA Model) by manipulating water flow to the process tank. The present set-up is completely computerized controlled. The Digital Indicating Controller have a facility to interface the system with computer which enables to change the PID parameters using computer. The educational software and data-logging package has been developed for unit. This software is compatible to interfacing unit designed by us. This software package provides a comprehensive educational software environment within which the PID investigations can be performed. This software is capable to tabulate the sample readings according to the requirement of experiment under study and results obtained can be compared. The real time data acquisition can be done by interfacing the set-up with computer using software. This software can be used outside the laboratory with the computer to familiarize the students with the equipment and procedures with the help of Flow Diagrams provided in the software. In flow diagrams Set Point, Process Variable and Controllers Output are visible on the screen and this data can be transferred in Excel Files for further calculations, plotting graphs etc. When real time data acquisition is done, display of SV, PV and Output is there on the screen. It also appears in graphical display. Software allows the user to have control on sampling time, data logging, printing the stored data.
EXPERIMENTATION:
To study the open loop or manual control
To study the proportional control
To study the two mode (P+I) control
To study the two mode (P+D) control
To study the three mode (PID) control
To study the tuning of controller (Open loop method) using Zeigler-Nichols method.
To study the stability of the system using the BODE PLOT.
Auto Tuning
UTILITIES REQUIRED:
Compressed Air Supply: 1 CMH at 6 BAR.
Electricity supply: 1 Phase, 220 VAC.
Computer: Pentium IV, Windows XP version pre-loaded. One RS 232 Serial communication port free for interfacing unit.
Table for Setup support.
TECHNICAL DETAILS:
Level Transmitter Range 0-300 mm, Capacitance Type, Output 4-20 mA
Process tank Material SS/Glass/Acrylic with Scale. Capacity 2 Ltrs approx.
Water Tank Material Stainless Steel, Capacity 10 Ltrs.
Water Circulation FHP Pump. Tullu/Champion make.
Flow Measurement Rotameter.
Control valve Compatible capacity with pneumatic actuator.
I/P converter Input 4-20mA, Output 3-15 PSIG.
Pressure Regulator 0-2 kg/cm².
Pressure Gauge Bourdon type, 0-2 kg/cm²
Piping Size ¼”
Interfacing unit For input-output communication with auto/manual facility
Micro-processor Controller PID Setting, auto tuning, fully programmable with serial communication
Software For experimentation, PID control, Data logging, trend plot, offline analysis and printing.
Instruction Manual An ENGLISH instruction manual will be provided along with the Apparatus
The whole unit is assembled rigidly on a base plate.
