Automation and process control are essential for the safe and profitable operation of different types of plants.
De Lorenzo Company has decided to consider as a reference a plant based on the control of common parameters in many process control systems such as flow, level, temperature and pressure; beside this and to understand well what happens in process control, it is also proposed a trainer complete of sensors and transducers which are most widely used in industry.
For the food, medicine, paper and other industries, a kneading machine is also available complete with sensors, PLC, touch screen and electrical and control cabinets.
For users who wish to study process control in a virtual way, there is a simulation software developed in Labview environment.
These trainers are recommended for high schools and first years of university.
Simulation software in LabVIEW environment.
The simulator is composed of two parts: the controller and the system to
The user can influence the behaviour of the system through the controller. The system is controlled by the following parameters of the actuators:
• Pump: input voltage (0V to 10V)
• Motor driven pump: angle (0° to 40°)
• Heating resistance: input voltage (0V to 10V)
and in the process tank:
• Manual output valve 1: angle (0° to 90°)
• Manual output valve 2: number of rpm
• Solenoid valve: on or off
• Air valve: on or off
The controller is composed of PID and On/Off controls that are used to control the temperature of the water, its pressure and its level inside the process tank.
The parameters can also be manually controlled.
System to be controlled
The system is composed of a didactic plant that consists in a pressurized process tank, a storage tank and a set of sensor and actuators for level, pressure, temperature and flow.
The behaviour of the system is modeled on the basis of the characteristics of the physical components. Under a given supply voltage, the pump creates a flow of water that also depends on the pressure in the system. In the process tank some amount of water may be stored and exert a hydrostatic pressure at the bottom. The process tank is also equipped with an air valve that can be used to control the pressure of the air inside the tank.
The output pressure from the tank is, therefore, the sum of the hydrostatic pressure and of the air pressure. The temperature of the water inside the process tank can be controlled by means of a heating resistance. To influence the pressure in the system also the valves may be used. The storage tank is used to store water for the system and there is atmospheric pressure at its output.
The simulator calculates and presents to the user the following parameters:
• Flow in the system
• Outflow from the process tank
• Pressure exerted on the pump
• Total pressure at the output of the tank
• Level of the water in the process tank
• Temperature of the water in the process tank
The trainer is composed of:
• an educational board with a pressurized vessel and a set of sensors and actuators for level, pressure, temperature and flow;
• a control module, containing the interface circuits for the sensors and the actuators and the ON/OFF, proportional, integral and derivative control circuits (PID).
Pressurized vessel capacity: 5 litres approx. Water tank capacity: 20 litres approx.
• platinum thermo-resistance Pt 100
• bi-metallic direct reading thermometer level sensor:
• Capacitive level sensor • Detecting range: 0 to 180mm
• Signal output: 0 to 5V Flux sensors:
• flowmeter 8000 pulses/ litre
• flowmeter, direct reading Pressure sensors:
• strain gauge
•manometer, direct reading Recirculation pump: 6 litres/minute, 12 V, 1.5 A Motor driven valve 4 manual valves Water heating resistance: 48V, 200W Safety valve set at 2.4 bar Safety thermostat Piping: brass Power supply: single-phase from mains With this system, the student will be able to study the following:
• Study of the level, flow, pressure and temperature sensors
• Study of the characteristics of the pump and of the motor pump
• Study of the characteristics of the static process and of the time constants
• ON-OFF, P, PI, PD and PID closed loop control of the level
• P, PI, PD and PID closed loop control of the flow
• ON-OFF, P, PI, PD and PID closed loop control of the temperature
• ON-OFF control of the level with the pressure sensor Optionally, it is possible to connect to the trainer:
• a microprocessor based process controller of industrial type (DL 2314C)
• a process recorder (DL 2314R)
• a programmable logic controller (DL 2210B)
• a personal computer with suitable interface module and software (PC with DL 1893 and DL 2314SW)
Industrial kneading machines are widely used in
food, medicine, rubber, paper and other industries.
They can realize stirring for a variety of raw
materials and can also achieve heating at the same
The kneading machine in this system is based on the machines that are commonly used in the food industry.
With reference to the actual teaching needs, the system includes the PLC control, variable frequency control, temperature control and touch screen control that are commonly used in industry, and covers the experimental trainings in sensor detection technology, food process control, power distribution technology and other subjects.
By performing the integrated experiments with this didactic system, students can master the following contents:
· Working principle and usage for industrial kneading machine;
· PLC principle and applications.
· PLC programming and communications.
· The basic principle and initial use of frequency converter.
· AC motor control technology.
· Temperature control theory and applications.
· Turbo motor theory and applications.
· Principle and application of industrial sensors.
· Industrial electrical power distribution cabinet layout and alignment.
· PLC control cabinet.
The trainer is composed of three independent modules:
· the main electrical cabinet.
· the kneading machine.
· the control cabinet.
The main electrical cabinet unit is mainly used to provide the power supply and protection for all devices. Its inside has a range of industrial devices such as air switch, AC contactor, thermal relay, frequency converter, etc.
The control cabinet is mainly used to achieve automatic control and monitoring for technological processes. It mainly includes the PLC, touch screen and other industrial devices.
The three units are installed with movable wheels, which make them independent in structure.
Power supply and distribution as well as electrical control between each unit are realized with the connection of cables.
This sensors and transducers trainer teaches the operating principles of
the sensors/transducers which are most widely used in industry. It is
subdivided in two sections: in the lower section there are all the input
and output transducers, while in the upper side there are all the signal
conditioning systems as well as the instrumentation.
With this system, the student will be able to study the following:
• Survey on the features of a position control system
• Features of a speed control system
• Application of the timer/counter as time meter
• Application of the timer/counter as tachometer or frequency meter
• Features of a visualization unit with graphic LED bar
• Features of a meter with mobile coil
• The buffer as compensator of the load effect of an output voltage in the potentiometer
• Servo‐potentiometer. Variation of the output voltage on the basis of its position
• Resistance measurement through a Wheatstone bridge
• Voltage measurement through null balance (two methods)
• Temperature features through integrated circuit LM 35
• Features of: a platinum transducer with resistor on the basis of temperature (RTD), a thermistor N.T.C., a thermistor using an alarm circuit (double thermistor), a thermocouple type “K”, a photovoltaic cell, a phototransistor, a detector of light intensity, a variable resistor, a flux meter, a pressure detector, an optoelectronic transducer with application for counting and speed measurement, a reflective opto transducer and the grey code disk, an inductive transducer, a Hall effect transducer, a tacho generator with dc permanent magnet, a dynamic microphone, an ultrasonic receptor, a loudspeaker coil, a buzzer, a dc solenoid, a dc relay, a permanent magnet motor, a dc current amplifier, a current amplifier and buffer amplifier application, a power amplifier and buffer, a differential amplifier, a V/I converter, a I/V converter, a V/F converter, a F/V converter, a full wave rectifier, a comparator, an alarm oscillator circuit, an electronic switch, an adder amplifier, an integrator amplifier, a differential amplifier, a Sample and Hold circuit, a humidity sensor.
THE TRAINER INCLUDES THE FOLLOWING INPUT SENSORS/TRANSDUCERS:
linear slide potentiometer, rotary potentiometer, precision servo potentiometer, Wheatstone bridge circuit, thermistors NTC, RTD platinum sensor, IC temperature sensor, thermocouple, phototransistor, PIN photodiode, photoconductive cell, photovoltaic cell, LVDT, extensiometric transducer, linear position sensor, air flow sensor, air pressure sensor, humidity sensor, opto‐electronic sensor, opto‐reflecting sensor, inductive sensor, Hall effect sensor, dc tacho generator, microphone;
THE FOLLOWING OUTPUT SENSORS/TRANSDUCERS: electric resistance, incandescent lamp, buzzer, moving coil loudspeaker, ultrasonic transmitter, ultrasonic receiver, dc solenoid, dc relay, dc motor;
AND THE FOLLOWING SIGNAL CONDITIONING COMPONENTS:
timer/counter, bar graphs, dc voltmeter, dc amplifiers, ac amplifiers, power amplifiers, current amplifiers, buffer amplifier, inverting amplifier, differential amplifier, V/F converter, F/V converter, I/V converter, V/I converter, complete wave rectifier, hysteresis switchable comparator, alarm oscillator, electronic switch, oscillator, filter, switchable low‐pas filter, power supply, adding amplifier, integrator with switchable time constant, instrumentation amplifier, sample & hold circuit, gain and off set control amplifier.