AUTOMATION AND PROCESS CONTROL MPCT - Modular Process Control Trainer Code 916960 Basic module and level control complete with optionals code 916961-916962-916963-916964-916965 1. General Didacta proposes a completely new solution for the study of process control techniques, characterized by: limited cost; high expandability and modularity; numerous applicative possibilities and exercises ready to be used; educational software for Windows. All is obtained through an open architecture built on a basic system, which allows the preliminary exercises on level control and by additional kits, in order to carry out respectively: flow control, pressure control, temperature control, ph control and conductibility control. The MPCT system is a modular and low cost trainer based on Personal Computer and suitable to study the Process Control techniques. The basic module includes the electrical equipment and the components for the Level control. Some additional kits allow to fulfill the Flow, Pressure, Temperature, ph and conductibility control by using most of the basic module components. An A/D-D/A card and an extremely evolved software allow to carry out the control, and to introduce disturbances via software in real time, to set PID or ON-OFF control parameters, to set the level or typology of the Set-Point and of the disturbance, to monitorize the quantities involved etc. In such a way, it is possible to carry out the laboratory activity in an extremely productive way using the potential of a Personal Computer. DIDACTA Italia S.r.l. - Strada del Cascinotto, 139/30-10156 Torino - Italy Tel. +39 011 2731708 - Fax +39 011 2733088 - http://www.didacta.it - E-mail: info@didacta.it
2. Composition The trainer consists of: Basic module and level control (code 916960); Optional kit for flow control (code 916961); Optional kit for pressure control (code 916962); Optional kit for temperature control (code 916963); Optional kit for ph control (code 916964); Optional kit for conductibility control (code 916965); Didactic regulation software MPCT/CRS (code 917024); Optional electronic regulator MiniReg (code 916940). Fig. 1 - Composition of the unit Fig.2 - Basic module scheme for level control (IN level signal, OUT1 actuating signal, OUT2 disturbance signal). 3. Description Basic module and level control (code 916960) Stainless steel water tank; Transparent Plexiglas graduated tank (dimensions: din. 40x300 mm); No. 2 peristaltic pumps operated by a direct current motor with permanent magnets, controlled by means of tachymetrical signal, respectively for the regulated quantity and the disturbance (max. capacity 7 l/h); Pressure transducer 0..50 mbar with output 4..20 ma; Electric power supply, signal conditioning and visualization unit; 12 bit A/D-D/A card for connection to a Personal Computer. It allows, without any addition, the study of the level regulation, as shown in Fig. 2. In this case, the pressure transducer supplies an electronic signal corresponding to the level of the liquid in the graduated tank. The regulating signal acts on the inflow to the tank, while the disturbance signal acts on the outflow. The electric equipment supplied with the basic module is already preset for all the optional kits; it includes, for example, the adaptor for the Pt100 probe included in the temperature kit and the frequency/voltage converter for the flow kit. Therefore the user can also install the additional modules at any moment in an easy and quick way. Kit for flow control, optional (code 916961) Turbine for flow measurement; Flowmeter for direct reading of the flow (max. capacity 12 l/h); Making use of the pumps and of the electric equipment included in the basic system, it is possible to fullfill the scheme of Fig. 3, and to fulfill a process in which the controlled quantity is a flow. Page 2
Fig. 3 - Basic module scheme with kit for flow control (IN flow signal, OUT1 actuating signal, OUT2 disturbance signal). Fig. 4 - Basic module scheme with pressure control kit (IN pressure signal, OUT1 actuating signal, OUT2 disturbance signal). Kit for pressure control, optional (code 916962) Hoffmann pinchcock plug for the basic module tank; Mechanical U manometer 0 300 mbar. The kit allows to fulfill a new process, in which the regulated variable is the pressure of the air chamber located between the liquid in the tank and the air tight cover, reaching in this way the scheme of Fig. 4. The pressure is controlled through the water inflow, while the disturbance is created by means of the outflow. Kit for the temperature control, optional (code 916963) Heating resistance with power of approx. 200W; Pt 100 thermoresistance; Thermometer for temperature reading in the hot water tank; Bimetallic thermostat for max temperature control. It is now possible to fulfill a process, in which the regulated quantity is the temperature of a liquid, according to the scheme of Fig. 5. The controlled quantity is the temperature of the liquid in the mixer, reached through the PT100 probe connected to the electric equipment for the digital visualization in centigrades, and the transmission of the electric signal to the A/D-D/A card. The electric coil supplied in the kit performs the heating action, while the cold water contained in the outflow tank performs the cooling action. The regulating signal acts on the hot water flow, while the disturbance signal causes the variation of the cold water inflow to the mixer. In case you may wish to extend the control for long, it is necessary to avoid the overheating of the water in the outflow tank, prearranging an external auxiliary water inflow, and allowing an external outflow for the hot water. A B Pump 2 Pump 1 OUT1 OUT2 IN C.R.P. Fig. 5 - Basic module scheme with temperature control kit (IN temperature signal, OUT1 actuating signal, OUT2 disturbance signal). Fig. 6 - Basic module scheme with ph control kit (IN temperature signal, OUT1 actuating signal, OUT2 disturbance signal)
Kit for the ph control, optional (code 916964) Disturbance and corrective solution tank, made of steel; PH measuring probe; Stirrer for controlled solution mixing. This kit allows to realize a process in which the regulated quantity is the ph of a liquid, according to the scheme of Fig. 6. PH is acquired by means of a probe connected to the electric equipment for the digital visualization and the transmission of the electric signal to the AID-D/A card. an acid mixture is in the disturbance solution tank, whereas a basic one is in the corrective solution tank. The liquid whose ph has to be controlled is in the equipment main tank. The user sets the disturbance solution flow-rate whereas the corrective solution flow-rate is fixed by the ph probe return signal; the pumps speeds is adjustable and allows to vary the flowrate of the two fluids. Besides, it is also possible to use a basic mixture as disturbance solution and an acid mixture as corrective solution. Kit for the conductibility control, optional (code 916965) conductibility measuring probe This kit allows to realize a process in which the regulated quantity is the conductibility of a liquid, according to the scheme of Fig. 7. Conductibility is acquired by means of a probe connected to the electric equipment for the digital visualization and the transmission of the electric signal to the AID-D/A card. By varying the water temperature, the conductibility also changes. Therefore the regulation is got by varying the cold/hot water flowrate up to reach the set point. The kit for conductibility control has to be supplied along with the optional kit for ph control (Code 916964). COLD HOT Pump 2 Pump 1 OUT1 OUT2 IN C.R.P. Fig. 7 - Basic module scheme with conductibility control kit (IN temperature signal, OUT1 actuating signal, OUT2 disturbance signal) Fig. 8 CRS/MPCT control regulation software Didactic regulation software MPTC/CRS (code 917024) The monitoring and control software allows the fulfillment of a digital control via software, of PID or ON-OFF type for all the previewed processes. It is not therefore necessary to have any other software in order to use the additional kits. It is possible to set, independently and in real time, the constants related to the type of control (proportional band, integral and derivative time for the PID, hysteresis band for the ON-OFF control), apart from the level or the grade of the set-point. Also the disturbance can be introduced from software. It is possible to choose among different types of disturbance: pulse, step, ramp, sinusoid verifying the answer of the system in the different cases. The software allows monitoring in real time, showing on the video the diagram of the regulated quantity, of the regulating signal, and of the set point in function of time (see Fig. 8). Such a diagram can be printed at any moment, while the signal samples and the control parameters can be saved in a file, in ASCII format, or printed. It is also possible to use the software exclusively for the acquisition and visualization of the regulating and regulated signals using an external regulator of electronic type for the control (e.g. the optional electronic regulator). In case an electronic regulator with input for remote Set-Point is used, as the optional electronic regulator, it is possible to vary the Set-Point of the regulator by software, simulating in that way a process with local regulator and remote set-point setting, visualizing the involved signals on video. Page 4
Optional electronic regulator MiniReg (code 916940) The MiniReg electronic regulator is a high reliability instrument, made with microprocessor digital technology, capable of regulating any physical quantity acquired by transducers with standard electrical output. The three-term electronic regulator (Proportional, Integral, Derivative) has the following characteristics: Set-Point settable both manually in a direct way and externally from remote; Setting of a ramp Set Point whose slope is calculated on an hour basis; Possibility to set independent max. and min. alarms; Memory in order to preserve the set parameters; Simple programming and recall of data using the keyboard; Clear visualization of alarms and parameters on display; Self-tuning possibility and automatic determination of the parameters of optimal regulation. 4. Applications Possibilities Study of the processes fulfilled with the different kits and of the components employed (e.g. determination of the characteristic of the thermoresistance employed on the temperature control or on the turbine used in the flow control); Manual process control; Determination of the characteristics of the system with open loop; Determination of the characteristics of the system with closed loop and PID control and check of the separated effect of the three regulating actions, proportional, integral, derivative; Study of the system stability in different conditions and calibration of the different actions of regulation; Determination of the system characteristics with closed loop with ON-OFF control; Comparison among processes having different time constants (level, flow, pressure, temperature, ph and conductibility) and among the problems connected to the related control; Study of the system response to different types of disturbances (pulse, step, ramp and sinusoid); Demonstration of the use of a local regulator of electronic type with remote set-point input. 5. PC configuration required Hardware PC min. Pentium with Hard Disk (>10Gb), and CD drive, SVGA graphic, Mouse, RAM 32 MB, USB porte. Graphic printer. Software Windows XP or following versions. 6. Services required Electric power supply: 220/240 V AC - 50/60 Hz. 7. Weight and dimensions Base system Dimensions: 700x400x1000 mm Weight: 50 kg approx. Additional kits They are made by different elements with contained weight and dimensions. Optional electronic regulator Dimensions: 200x350x200 mm Weight: 1.5 kg
Cod. R00787/E 0910 Ed. 01 Rev. 04 In any time and without notice, Didacta Italia can carry out any appropriate modification on the product details, always maintaining their main features, according to the designing and teaching necessity. Page 6