Lectures on instruments and automation equipment. Automation of technological processes and production. Production automation technologies. And automation tools

The definitions of “automation object” include a variety of technical objects(metallurgical furnaces, transport, various machines and others technical devices), as well as production processes that can be performed by one or a whole complex of technological units, installations or machines in their interaction with the control system. At this stage of human development, automation is actively being introduced into all areas human life, .

Continuous improvement and implementation of automation systems are absolutely interconnected processes. On the one hand, to modernize various industries it is necessary to develop and implement mechanization and automation systems into already operating mechanisms, and on the other hand, when creating a completely new technology, it is necessary to provide ways for its effective automation.

According to their hierarchy, automation technical means are classified into two classes:

• Systems for automated (automatic) regulation of ACS and control of ACS;
• Devices, elements and subsystems of automatic control systems and self-propelled guns;

The common functional part of both systems is the object of regulation (control). Control object – a controlled part of the system (a machine or a set of machines), the established operating mode of which must be supported by the control part of the system in accordance with the previously selected control task.

A control system (CS) is a dynamic closed complex that consists of controlled objects and three subsystems: logical-computational, information and executive. A general diagram is shown below:

An information subsystem is a set of technical means for receiving, presenting and transmitting information. The means whose purpose is to obtain and transform primary information about the internal and external factors of the operation of objects under control include measuring and sensitive elements, analyzers, primary information sensors and other devices. This category also includes means for presenting and transmitting information in a form convenient for the control system - receivers, encoding/decoding devices, transmitters, communication channels, and so on.

Logic-computing system – technical means whose task is to process information.

The main task of information processing tools is to develop solutions necessary to achieve control tasks formulated in the technical specifications for the manufacture of self-propelled guns. These solutions are usually implemented in the form of master or control signals. Technical means of information processing include a variety of analog and digital computing tools, including microcontrollers.

Technical means that are used to generate control signals and directly control the object are called executive subsystem . The technical means of executive subsystems mainly include electric drives, as well as lighting and temperature controllers, electromagnets hydraulic mechanisms and so on.

Control systems, during the operation of which, including the stages of decision-making and development of control actions, are completely absent from the participation of the operator (the operator only observes the production process) are called systems automatic control self-propelled guns .

Control systems in which computers (digital, analog or hybrid) are involved when the operator makes decisions are called automated control systems.

Technical automation equipment

instruments, devices and technical systems intended for production automation (See Production automation). T.s. A. provide automatic receipt, transmission, transformation, comparison and use of information for control and management purposes production processes. In the USSR, a systematic approach to the construction and use of technical systems. A. (their grouping and unification according to functional, informational, and design-technological characteristics) made it possible to unite all technical systems. A. within the framework of the State System of Industrial Instruments and Automation Equipment - GSP.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what “Technical automation equipment” is in other dictionaries:

TECHNICAL TOOLS (AUTOMATION)- 13. TECHNICAL TOOLS (AUTOMATION) automation equipment that does not use software. Source: RB 004 98: Requirements for certification of control systems important for the safety of nuclear power plants...

technical means of automation- instruments, devices and technical systems for automated production, providing automatic receipt, transmission, transformation, comparison and information for the purpose of monitoring and managing production... ... encyclopedic Dictionary in metallurgy

I&C automation equipment, I&C technical support- 7 Technical means of automation of the I&C system, technical support of the I&C system The set of all components of the I&C system, with the exception of people (GOST 34.003 90). The totality of all technical means used in the operation of I&C systems (GOST 34.003 90) Source ... Dictionary-reference book of terms of normative and technical documentation

AUTOMATION SOFTWARE AND HARDWARE TOOLS- 7. SOFTWARE AND HARDWARE AUTOMATION TOOLS a set of software and hardware automation tools designed to create control software and hardware systems. Source: RB 004 98: Requirements for certification of managers... ... Dictionary-reference book of terms of normative and technical documentation

Technical means- 3.2 Technical means of automation systems, a set of technical means (CTS) a set of devices (products) that provide receiving, input, preparation, conversion, processing, storage, registration, output, display, use and... ... Dictionary-reference book of terms of normative and technical documentation

Means of technical automation systems- 4.8 Source: RM 4 239 91: Automation systems. Dictionary reference book on terms. Manual for SNiP 3.05.07 85 ... Dictionary-reference book of terms of normative and technical documentation

Technical means of automated process control systems- Automated process control systems, including products of the state system of industrial instruments and automation equipment (GSP), aggregate measuring instruments (AS IMS), computer equipment (SVT) Source: RD 34.35.414 91: Rules of the organization ... ... Dictionary-reference book of terms of normative and technical documentation

AUTOMATION SYSTEMS TECHNICAL EQUIPMENT- 4.8. TECHNICAL TOOLS OF AUTOMATION SYSTEMS Hardware hardware A set of tools that ensures the functioning of automated systems of various types and levels: devices, functional blocks, regulators, actuators, aggregate complexes,... ... Dictionary-reference book of terms of normative and technical documentation

GOST 13033-84: GSP. Electrical analog instruments and automation equipment. General technical conditions- Terminology GOST 13033 84: GSP. Electrical analog instruments and automation equipment. General technical conditions original document: 2.10. Power requirements 2.10.1. The products must be powered from one of the following sources: ... ... Dictionary-reference book of terms of normative and technical documentation

Technical- 19. Technical instructions on the production technology of construction and installation work during the electrification of railways (power supply devices). M.: Orgtransstroy, 1966. Source: VSN 13 77: Instructions for installing contact networks of industrial ... Dictionary-reference book of terms of normative and technical documentation

Books

• Technical means of automation and control Textbook, Kolosov O., Yesyutkin A., Prokofiev N. (eds.). The textbook, to varying degrees (without pretending to cover the “immense”), reinforces and complements the materials presented in accordance with the work programs of a complex of disciplines of the professional cycle...
• Technical means of automation. Textbook for academic bachelor's degree, Rachkov M.Yu.. The textbook discusses the classification of technical automation equipment, methods for selecting technical equipment by type of production, as well as equipment control systems. A description is provided...

Technical automation equipment (TAA) is designed to create systems that perform specified technological operations, in which humans are mainly assigned control and management functions.

Based on the type of energy used, technical automation equipment is classified into: electric, pneumatic, hydraulic And combined. Electronic automation tools are classified as a separate group, since they, using electrical energy, are designed to perform special computing and measuring functions.

According to their functional purpose, technical automation equipment can be divided in accordance with the standard diagram of an automatic control system into actuators, amplifiers, correcting and measuring devices, converters, computing and interface devices.

Executive element - This is a device in an automatic regulation or control system that acts directly or through a matching device on a regulatory element or object of the system.

Regulating element carries out a change in the operating mode of the managed object.

Electrical actuator with mechanical output - electric motor- used as a terminal amplifier of mechanical power. The effect exerted by an object or mechanical load on an actuator is equivalent to the action of internal, or natural, feedback. This approach is used in cases where a detailed structural analysis of the properties and dynamic features of the actuating elements is required, taking into account the action of the load. An electrical actuator with a mechanical output is an integral part of the automatic drive.

Electric drive - This is an electrical actuator that converts the control signal into a mechanical action while simultaneously amplifying it in power due to an external energy source. The drive does not have a special main feedback link and is a combination of a power amplifier, an electrical actuator, a mechanical transmission, a power source and auxiliary elements, united by certain functional connections. The output quantities of the electric drive are linear or angular speed, traction force or torque, mechanical power etc. The electric drive must have the appropriate power reserve necessary to influence the controlled object in forced mode.

Electric servomechanism is a servo drive that processes the input control signal with amplification of its power. The elements of the electrical servomechanism are covered by special feedback elements and can have internal feedback due to the load.

Mechanical transmission The electric drive or servomechanism coordinates the internal mechanical resistance of the actuator with the mechanical load - the regulatory body or control object. Mechanical transmissions include various gearboxes, crank, lever mechanisms and other kinematic elements, including transmissions with hydraulic, pneumatic and magnetic supports.

Electrical power supplies actuators, devices and servomechanisms are divided into sources with practically infinite power, with a value of their internal resistance close to zero, and sources with limited power with a value of internal resistance different from zero.

Pneumatic and hydraulic actuators are devices that use gas and liquid, respectively, under a certain pressure as an energy carrier. These systems occupy a strong place among other automation equipment due to their advantages, which, first of all, include reliability, resistance to mechanical and electromagnetic influences, a high ratio of the developed drive power to its own weight and fire and explosion safety.

The main task of the actuator is to amplify the signal arriving at its input to a power level sufficient to have the required effect on the object in accordance with the stated control goal.

An important factor when choosing an actuator is to ensure the specified system quality indicators with the available energy resources and permissible overloads.

The characteristics of the actuator must be determined from the analysis of the automated process. Such characteristics of actuators and servomechanisms are energy, static, dynamic characteristics, as well as technical, economic and operational characteristics.

A mandatory requirement for the actuator drive is to minimize engine power while ensuring the required speeds and torques. This leads to minimization of energy costs. Very important factors when choosing an actuator or servo mechanism are restrictions on weight, overall dimensions and reliability.

Important components of automation systems are amplification and correction devices. Common tasks solved by correction and amplification devices of automation systems are the formation of the required static and frequency characteristics, synthesis of feedback, coordination with the load, ensuring high reliability and unification of devices.

Amplifier devices the power of the signal is amplified to the level necessary to control the actuator.

Special requirements for corrective elements of systems with variable parameters are the possibility and ease of restructuring the structure, program and parameters of corrective elements. Amplifier devices must satisfy certain technical specifications by specific and maximum output power.

The structure of an amplification device is, as a rule, a multistage amplifier with complex feedback connections, which are introduced to improve its static, dynamic and operational characteristics.

Amplification devices used in automation systems can be divided into two groups:

1) electrical amplifiers with electrical power sources;

2) hydraulic and pneumatic amplifiers, using liquid or gas, respectively, as the main energy carrier.

The power source or energy carrier determines the most essential features of automation amplification devices: static and dynamic characteristics, specific and maximum power, reliability, operational and technical and economic indicators.

Electrical amplifiers include electronic vacuum, ionic, semiconductor, dielectric, magnetic, magnetic-semiconductor, electric machine and electromechanical amplifiers.

Quantum amplifiers and generators constitute a special subgroup of devices used as amplifiers and converters of weak radio and other signals.

Corrective devices generate correction signals for the static and dynamic characteristics of the system.

Depending on the type of inclusion in the system, linear corrective devices are divided into three types: serial, parallel corrective elements and corrective feedback. The use of one or another type of correction devices is determined by the convenience of technical implementation and operational requirements.

It is advisable to use corrective elements of the sequential type if the signal, the value of which is functionally related to the error signal, is an unmodulated electrical signal. The synthesis of a sequential correction device in the process of designing a control system is the simplest.

Parallel type correction elements are convenient to use when forming a complex control law with the introduction of an integral and derivatives of the error signal.

Corrective feedback, covering amplifiers or actuators, is most widely used due to the simplicity of its technical implementation. In this case, the input of the feedback element receives a relatively high level signal, for example, from the output stage of an amplifier or motor. The use of corrective feedback makes it possible to reduce the influence of nonlinearities of those system devices that are covered by them; therefore, in some cases it is possible to improve the quality of the control process. Corrective feedback stabilizes the static coefficients of the covered devices in the presence of interference.

Automatic regulation and control systems use electrical, electromechanical, hydraulic and pneumatic corrective elements and devices. Electrical correction devices are most simply implemented using passive quadripoles, which consist of resistors, capacitors and inductances. Complex electrical correction devices also include separating and matching electronic elements.

Electromechanical correction devices, in addition to passive quadripoles, include tachogenerators, impellers, differentiating and integrating gyroscopes. In some cases, an electromechanical correction device can be implemented in the form of a bridge circuit, in one of the arms of which an electric motor of the actuator is connected.

Hydraulic and pneumatic correction devices can consist of special hydraulic and pneumatic filters included in the feedback loops of the main elements of the system, or in the form of flexible feedback loops for pressure (pressure difference), flow rate of working fluid, or air.

Corrective elements with tunable parameters ensure system adaptability. The implementation of such elements is carried out using relay and discrete devices, as well as computers. Such elements are usually referred to as logical corrective elements.

A computer operating in real time in a closed control loop has practically unlimited computing and logical capabilities. The main function of the control computer is to calculate optimal controls and laws that optimize the behavior of the system in accordance with one or another quality criterion during its normal operation. The high speed of the control computer allows, along with the main function, to perform a number of auxiliary tasks, for example, with the implementation of a complex linear or nonlinear digital correction filter.

In the absence of computers in systems, it is most advisable to use nonlinear correcting devices as they have the greatest functional and logical capabilities.

Regulating devices They are a combination of actuators, amplifying and correcting devices, converters, as well as computing and interface units.

Information about the parameters of the control object and about possible external influences affecting it is received by the control device from measuring device. Measuring devices in the general case, they consist of sensitive elements that perceive changes in the parameters by which the process is regulated or controlled, as well as additional converters that often perform signal amplification functions. Together with sensitive elements, these converters are designed to convert signals of one physical nature into another, corresponding to the type of energy used in the automatic regulation or control system.

In automation converting devices or converters These are elements that do not directly perform the functions of measuring regulated parameters, amplifying signals or correcting the properties of the system as a whole and do not have a direct impact on the regulatory body or the controlled object. Converting devices in this sense are intermediate and perform auxiliary functions associated with the equivalent transformation of a quantity of one physical nature into a form more convenient for the formation of a regulatory effect or for the purpose of coordinating devices that differ in the type of energy at the output of one and the input of another device.

Computer devices for automation equipment are, as a rule, built on the basis of microprocessor-based tools.

Microprocessor- a software-controlled tool that carries out the process of processing and managing digital information, built on one or more integrated circuits.

The main technical parameters of microprocessors are the bit depth, addressable memory capacity, versatility, the number of internal registers, the presence of microprogram control, the number of interrupt levels, the type of stack memory and the number of main registers, as well as the composition of the software. Based on their word width, microprocessors are divided into microprocessors with a fixed word width and modular microprocessors with variable word width.

By microprocessor means are structurally and functionally complete products of computer and control equipment, built in the form or on the basis of microprocessor integrated circuits, which, from the point of view of requirements for testing, acceptance and delivery, are considered as a single whole and are used in the construction of more complex microprocessor tools or microprocessor systems.

Structurally, microprocessor means are made in the form of a microcircuit, single-board product, monoblock or standard complex, and products of the lower level of the structural hierarchy can be used in products of the highest level.

Microprocessor systems - These are computing or control systems built on the basis of microprocessor-based tools that can be used autonomously or integrated into a controlled object. Structurally, microprocessor systems are made in the form of a microcircuit, a single-board product, a monoblock complex or several products of the indicated types, built into the equipment of the controlled object or made autonomously.

According to the scope of application, technical means of automation can be divided into technical means of automation of work on industrial production and technical means of automation of other work, the most important component of which is work in extreme conditions where human presence is life-threatening or impossible. In the latter case, automation is carried out on the basis of special stationary and mobile robots.

Technical means of automation of chemical production: Reference. ed./V.S.Balakirev, L.A.Barsky, A.V.Bugrov, etc. - M.: Chemistry, 1991. –272 p.

Topic 2

1. Sensors

A sensor is a device that converts the input influence of any physical quantity into a signal convenient for further use.

The sensors used are quite varied and can be classified according to various signs(see table 1).

Depending on the type of input (measured) quantity, there are: mechanical displacement sensors (linear and angular), pneumatic, electrical, flow meters, speed, acceleration, force, temperature, pressure sensors, etc.

Based on the type of output value into which the input value is converted, non-electrical and electrical are distinguished: direct current sensors (EMF or voltage), amplitude sensors alternating current(EMF or voltage), alternating current frequency sensors (EMF or voltage), resistance sensors (active, inductive or capacitive), etc.

Most sensors are electrical. This is due to the following advantages electrical measurements:

It is convenient to transmit electrical quantities over a distance, and the transmission is carried out with high speed;

Electrical quantities are universal in the sense that any other quantities can be converted into electrical quantities and vice versa;

They are accurately converted into a digital code and allow you to achieve high accuracy, sensitivity and speed of measurement instruments.

Based on their operating principle, sensors can be divided into two classes: generator and parametric. A separate group consists of radioactive sensors. Radioactive sensors are sensors that use phenomena such as changes in parameters under the influence of g and b rays; ionization and luminescence of certain substances under the influence of radioactive irradiation. Generator sensors directly convert the input value into electrical signal. Parametric sensors convert the input value into a change in any electrical parameter (R, L or C) of the sensor.

Based on the principle of operation, sensors can also be divided into ohmic, rheostatic, photoelectric (optoelectronic), inductive, capacitive, etc.

There are three classes of sensors:

Analog sensors, i.e. sensors that produce an analog signal proportional to the change in the input value;

Digital sensors that generate a pulse train or binary word;

Binary (binary) sensors that produce a signal of only two levels: “on/off” (0 or 1).

Figure 1 – Classification of sensors for mining machine automation systems

Requirements for sensors:

Unambiguous dependence of the output value on the input value;

Stability of characteristics over time;

High sensitivity;

Small size and weight;

No feedback on controlled process and on the controlled parameter;

Work under various operating conditions;

Various options installation

Parametric sensors

Parametric sensors are sensors that convert input signals into a change in some parameter. electrical circuit(R, L or C). In accordance with this, active resistance, inductive, and capacitive sensors are distinguished.

Characteristic feature of these sensors is that they are used only with an external power source.

In modern automation equipment, various parametric active resistance sensors are widely used - contact, rheostatic, potentiometric sensors.

Contact sensors. The most reliable with contact sensors Magnetically controlled sealed contacts (reed switches) are considered.

Figure 1 – Schematic diagram of a reed switch sensor

The sensor's sensing element, the reed switch, is an ampoule 1, inside of which contact springs (electrodes) 2, made of ferromagnetic material, are sealed. The glass ampoule is filled with a protective gas (argon, nitrogen, etc.). The tightness of the ampoule excludes bad influence(impact) of the environment on the contacts, increasing the reliability of their operation. The contacts of the reed switch located at the controlled point in space close under the action magnetic field, which is created by a permanent magnet (electromagnet) installed on a moving object. When the reed switch contacts are open, its active resistance is equal to infinity, and when closed, it is almost zero.

Sensor output signal (U out on load R1) equal to voltage U p of the power source in the presence of a magnet (object) at the control point and zero in its absence.

Reed switches are available with both make and break contacts, as well as switching and polarized contacts. Some types of reed switches - KEM, MKS, MKA.

The advantages of reed switch sensors are high reliability and mean time between failures (about 10 7 operations). The disadvantage of reed sensors is a significant change in sensitivity with a slight displacement of the magnet in the direction perpendicular to the movement of the object.

Reed sensors are used, as a rule, in the automation of lifting, drainage, ventilation and conveyor installations.

Potentiometric sensors. Potentiometric sensors are a variable resistor (potentiometer) consisting of a flat (strip), cylindrical or ring frame on which a thin wire of constantan or nichrome with high resistivity. A slider moves along the frame - a sliding contact connected mechanically to the object (see Figure 2).

By moving the slider using the appropriate drive, you can change the resistance of the resistor from zero to maximum. Moreover, the resistance of the sensor can change both according to a linear law and according to other, often logarithmic, laws. Such sensors are used in cases where it is necessary to change the voltage or current in the load circuit.

Figure 2 - Potentiometric sensor

For a linear potentiometer (see Figure 2) length l the output voltage is determined by the expression:

,

where x is the movement of the brush; k=U p / l- transfer coefficient; U p – supply voltage.

Potentiometric sensors are used to measure various process parameters - pressure, level, etc., previously converted by a sensing element in motion.

The advantages of potentiometric sensors are design simplicity, small sizes, as well as the possibility of power supply with both direct and alternating current.

The disadvantage of potentiometric sensors is the presence of a sliding electrical contact, which reduces the reliability of operation.

Inductive sensors. The principle of operation of the inductive sensor is based on a change in the inductance L of the coil 1, placed on the ferromagnetic core 2, when moving x anchors 3 (see Figure 3).

Figure 3 - Inductive sensor

The sensor circuit is powered from an AC source.

The control element of the sensors is a variable reactance - a choke with a variable air gap.

The sensor works as follows. Under the influence of an object, the armature, approaching the core, causes an increase in flux linkage and, consequently, inductance of the coil. With decreasing gap d to a minimum value, the inductive reactance of the coil x L = wL = 2pfL increases to a maximum, reducing the load current RL, which is usually an electromagnetic relay. The latter, with their contacts, switch control, protection, monitoring circuits, etc.

The advantages of inductive sensors are the simplicity of the device and reliability of operation due to the absence of a mechanical connection between the core and the armature, which is usually attached to a moving object, the position of which is controlled. The functions of an anchor can be performed by an object itself that has ferromagnetic parts, for example a skip when controlling its position in the shaft.

The disadvantages of inductive sensors are the nonlinearity of the characteristics and the significant electromagnetic force of attraction of the armature to the core. To reduce forces and continuously measure displacements, solenoid-type sensors are used, or they are called differential.

Capacitive sensors. Capacitive sensors are structurally variable capacitors of various designs and shapes, but always with two plates, between which there is a dielectric medium. Such sensors are used to convert mechanical linear or angular movements, as well as pressure, humidity or environmental level into a change in capacity. In this case, to control small linear movements, capacitors are used in which the air gap between the plates changes. To control angular movements, capacitors with a constant gap and variable working area of ​​the plates are used. To control the filling levels of tanks with bulk materials or liquids at constant gaps and working areas of the plates, capacitors with the dielectric constant of the medium are controlled. The electrical capacity of such a capacitor is calculated by the formula

where: S - Total intersection area of ​​the plates; δ - distance between plates; ε is the dielectric constant of the medium between the plates; ε 0 is the dielectric constant.

Based on the shape of the plates, flat, cylindrical and other types of variable capacitors are distinguished.

Capacitive sensors only operate at frequencies above 1000Hz. Use at industrial frequency is practically impossible due to the high capacitance (Xc = = ).

Generator sensors

Generator sensors are sensors that directly convert various types of energy into electrical energy. They do not require external power sources because they themselves produce emf. Generator sensors use well-known physical phenomena: the occurrence of EMF in thermocouples when heated, in photocells with a barrier layer when illuminated, the piezoelectric effect and the phenomenon of electromagnetic induction.

Induction sensors. IN induction sensors conversion of an input non-electrical quantity into an induced emf. used to measure movement speed, linear or angular movements. E.m.f. in such sensors it is induced in coils or windings made of copper insulated wire and placed on magnetic cores made of electrical steel.

Small-sized microgenerators that convert the angular velocity of an object into emf, the value of which is directly proportional to the rotation speed of the output shaft of the test object, are called tachogenerators of direct and alternating currents. Circuits of tachogenerators with and without an independent excitation winding are shown in Figure 4.

Figure 4 - Schemes of tachogenerators with and without an independent excitation winding

DC tachogenerators are a commutator electric machine with an armature and an excitation winding or permanent magnet. The latter do not require an additional power source. The principle of operation of such tachogenerators is that an emf is induced in the armature, which rotates in the magnetic flux (F) of a permanent magnet or field winding. (E), the value of which is proportional to the rotation frequency (ω) of the object:

E = cФn = cФω

To save linear dependence e.m.f. depending on the speed of rotation of the armature, it is necessary that the load resistance of the tachogenerator always remains unchanged and is many times higher than the resistance of the armature winding. The disadvantage of DC tachogenerators is the presence of a commutator and brushes, which significantly reduces its reliability. The collector provides conversion of alternating emf. anchors in D.C..

More reliable is an alternating current tachogenerator, in which the output intrinsically safe winding is located on the stator, and the rotor is permanent magnet with a corresponding constant magnetic flux. Such a tachogenerator does not require a collector, but its variable emf. converted to direct current using bridge diode circuits. The principle of operation of a synchronous alternating current tachogenerator is that when the rotor is rotated by the control object, a variable emf is induced in its winding, the amplitude and frequency of which are directly proportional to the rotor rotation speed. Due to the fact that the magnetic flux of the rotor rotates at the same frequency as the rotor itself, such a tachogenerator is called synchronous. Disadvantage synchronous generator is that it has bearing units, which is not appropriate for mining conditions. The diagram for controlling the speed of a conveyor belt with a synchronous tachogenerator is shown in Figure 5. Figure 5 indicates: 1 - magnetic rotor of the tachogenerator, 2 - drive roller with tread, 3 - conveyor belt, 4 - stator winding of the tachogenerator.

Figure 5 - Scheme for synchronous conveyor belt speed control

tachogenerator

For measuring linear speed To measure the movement of the working parts of scraper conveyors, magnetic induction sensors are used, which have no moving parts at all. The moving part (armature) in this case is the steel scrapers of the conveyor, moving in the magnetic flux of a permanent magnet sensor with an intrinsically safe coil. When steel scrapers cross a magnetic flux in the coil, a variable emf is induced, directly proportional to the speed of movement and inversely proportional to the gap between the steel core of the coil and the scraper. The magnetic flux, which leads to the emf, in the coil in this case changes under the influence of steel scrapers, which, moving above the sensor, cause fluctuations in the magnetic resistance along the path of closing the magnetic flux formed by the permanent magnet. The diagram for monitoring the speed of movement of the working body of a scraper conveyor using a magnetic induction sensor is shown in Figure 6. Figure 6 indicates: 1 - scraper conveyor, 2 - steel core, 3 - steel washer, 4 - plastic washer, 5 - ring permanent magnet, 6 - sensor coil

Figure 6 - Scheme for controlling the speed of movement of the working body

scraper conveyor with magnetic induction sensor

Magnetoelastic sensors. The principle of operation of magnetoelastic sensors is based on the property of ferromagnetic materials to change the magnetic permeability m when they are deformed. This property is called magnetoelasticity, which is characterized by magnetoelastic sensitivity

Permallay (iron-nickel alloy) has the highest value S m = 200 H/m2. Some varieties of permallay, when elongated by 0.1%, increase the coefficient of magnetic permeability up to 20%. However, to obtain even such small elongations, a load of the order of 100 - 200 N/mm is required, which is very inconvenient and leads to the need to reduce the cross-section of the ferromagnetic material and requires a power source with a frequency of the order of kilohertz.

Structurally, the magnetoelastic sensor is a coil 1 with a closed magnetic circuit 2 (see Figure 7). The controlled force P, deforming the core, changes its magnetic permeability and, consequently, the inductive resistance of the coil. The load current RL, for example, a relay, is determined by the resistance of the coil.

Magnetoelastic sensors are used to monitor forces (for example, when loading skips and planting cages on fists), rock pressures, etc.

The advantages of magnetoelastic sensors are simplicity and reliability.

Disadvantages of magnetoelastic sensors - required expensive materials for magnetic cores and their special processing.

Figure 7 – Magnetoelastic sensor

Piezoelectric sensors. The piezoelectric effect is inherent in single crystals of some dielectric substances (quartz, tourmaline, Rochelle salt, etc.). The essence of the effect is that under the action of dynamic mechanical forces on the crystal, electric charges arise on its surfaces, the magnitude of which is proportional to the elastic deformation of the crystal. The dimensions and number of crystal plates are selected based on the strength and the required amount of charge. Piezoelectric sensors in most cases are used to measure dynamic processes and shock loads, vibration, etc.

Thermoelectric sensors. To measure temperatures in within wide limits 200-2500 °C thermoelectric sensors are used - thermocouples, which ensure the conversion of thermal energy into electrical emf. The principle of operation of a thermocouple is based on the phenomenon of the thermoelectric effect, which consists in the fact that when the junction and ends of thermoelectrodes are placed in an environment with different temperatures t 1 and t 2 in a circle formed by a thermocouple and a millivoltmeter, a thermo emf appears, proportional to the difference between these temperatures

Figure 8 - Thermocouple diagram

Conductors A and B of thermocouples are made of dissimilar metals and their alloys. The phenomenon of thermoelectric effect is given by a combination of such conductors A and B, copper-constantan (up to 300 ° C), copper - kopel (up to 600 ° C), chromel - kopel (up to 800 ° C), iron - kopel (up to 800 ° C) , chromel - alumel (up to 1300 ° C), platinum - platinum-rhodium (up to 1600 ° C), etc.

Thermal emf value for various types thermocouples range from tenths to tens of millivolts. For example, for a copper-constantan thermocouple it changes from 4.3 to –6.18 mB when the junction temperature changes from + 100 to – 260 o C.

Thermistor sensors. The operating principle of thermistor sensors is based on the property of the sensing element - the thermistor - to change resistance when the temperature changes. Thermistors are made of metals (copper, nickel, atin, etc.) and semiconductors (mixtures of metal oxides - copper, manganese, etc.). A metal thermistor is made of wire, for example copper, with a diameter of approximately 0.1 mm, wound in the form of a spiral on a mica, porcelain or quartz frame. Such a thermistor is enclosed in a protective tube with terminal clamps, which is located at the temperature control point of the object.

Semiconductor thermistors are manufactured in the form of small rods and disks with leads.

With increasing temperature, the resistance of metal thermistors increases, while for most semiconductor ones it decreases.

The advantage of semiconductor thermistors is their high thermal sensitivity (30 times more than that of metal ones).

The disadvantage of semiconductor thermistors is the large spread of resistance and low stability, which makes them difficult to use for measurements. Therefore, semiconductor thermistors in mine automation systems technological installations mainly used to monitor the temperature values ​​of objects and their thermal protection. In this case, they are usually connected in series with an electromagnetic relay to the power source.

To measure temperature, the thermistor RK is included in a bridge circuit, which converts the resistance measurement into a voltage at the output Uout, used in the automatic control system or measuring system.

The bridge can be balanced or unbalanced.

A balanced bridge is used with the zero measurement method. In this case, the resistance R3 is changed (for example, by a special automatic device) following the change in the resistance of the thermistor Rt in such a way as to ensure equality of potential at points A and B. If the scale of the resistor R3 is graduated in degrees, then the temperature can be read by the position of its slider. The advantage of this method is high accuracy, but the disadvantage is the complexity of the measuring device, which is an automatic tracking system.

An unbalanced bridge produces a signal Uout, proportional to the overheating of the object. By selecting the resistances of resistors R1, R2, R3, the equilibrium of the bridge is achieved at the initial temperature value, ensuring that the condition is met

Rt / R1= R3 / R2

If the value of the controlled temperature and, accordingly, the resistance Rt changes, the balance of the bridge will be disrupted. If you connect an mV device with a scale graduated in degrees to its output, the device’s needle will show the measured temperature.

Induction flow meter

For feed control pumping unit For drainage, it is possible to use induction flow meters, for example, type IR-61M. The operating principle of an induction flow meter is based on Faraday's law (the law of electromagnetic induction).

The design diagram of an induction flowmeter is shown in Figure 9. When a conducting liquid flows in a pipeline between the poles of a magnet, an emf appears in the direction perpendicular to the direction of the liquid and in the direction of the main magnetic flux. U on the electrodes, proportional to the fluid velocity v:

where B is the magnetic induction in the gap between the magnet poles; d – internal diameter of the pipeline.

Figure 9 – Design diagram of an induction flow meter

If we express the speed v in terms of the volumetric flow rate Q, i.e.

Advantages of an induction flow meter:

They have a slight inertia of readings;

There are no parts inside the working pipeline (therefore they have minimal hydraulic losses).

Disadvantages of the flow meter:

The readings depend on the properties of the liquid being measured (viscosity, density) and the nature of the flow (laminar, turbulent);

Ultrasonic flow meters

The operating principle of ultrasonic flow meters is that

the speed of propagation of ultrasound in a moving medium of gas or liquid is equal to the geometric sum of the average speed of movement of the medium v ​​and the natural speed of sound in this medium.

The design diagram of the ultrasonic flow meter is shown in Figure 10.

Figure 10 - Design diagram of an ultrasonic flow meter

The emitter I creates ultrasonic vibrations with a frequency of 20 Hz and higher, which fall on the receiver P, which registers these vibrations (it is located at a distance l). Flow rate F is equal to

where S is the cross-sectional area of ​​the fluid flow; C – speed of sound in the medium (for liquid 1000-1500 m/s);

t1 is the duration of propagation of the sound wave in the direction of flow from the emitter I1 to the receiver P1;

t 2 – duration of propagation of the sound wave against the flow from the emitter I2 to the receiver P2;

l is the distance between the emitter I and the receiver P;

k – coefficient taking into account the distribution of speeds in the flow.

Advantages of an ultrasonic flow meter:

a) high reliability and speed;

b) the ability to measure non-conductive liquids.

Disadvantage: increased requirements for contamination of the controlled water flow.

2. Data transmission devices

Information is transferred from the automation object to the control device via communication lines (channels). Depending on the physical medium through which information is transmitted, communication channels can be divided into the following types:

– cable lines – electrical (symmetrical, coaxial, “ twisted pair", etc.), fiber-optic and combined electrical cables with fiber-optic cores;

– power low-voltage and high-voltage electrical networks;

– infrared channels;

– radio channels.

Information transmission over communication channels can be transmitted without information compression, i.e. One information signal (analog or discrete) is transmitted over one channel, and with information compression, many information signals are transmitted over a communication channel. Information compaction is used for remote transmission of information over a considerable distance (for example, from automation equipment located on a roadway to a shearer or from a section of a mine to the surface to a dispatcher) and can be done using various types of signal coding.

Technical systems, which ensure the transmission of information about the state of the object and control commands over a distance via communication channels can be remote control and measurement systems or telemechanical systems. In remote control and measurement systems, each signal uses its own line - a communication channel. As many signals as there are, so many communication channels are required. Therefore, with remote control and measurement, the number of controlled objects, especially over long distances, is usually limited. In telemechanical systems, only one line, or one communication channel, is used to transmit many messages to a large number of objects. Information is transmitted in encoded form, and each object “knows” its code, so the number of controlled or managed objects is practically unlimited, only the code will be more complex. Telemechanics systems are divided into discrete and analog. Discrete telecontrol systems are called telealarm systems(TS), they provide the transmission of a finite number of object states (for example, “on”, “off”). Analog television monitoring systems are called telemetering systems(TI), they provide the transmission of continuous changes in any parameters characterizing the state of the object (for example, changes in voltage, current, speed, etc.).

The elements that make up discrete signals have various qualitative characteristics: pulse amplitude, pulse polarity and duration, frequency or phase of alternating current, code in sending a series of pulses. Telemechanical systems are discussed in more detail in.

To exchange information between microprocessor controllers of various automation system devices, including control computers, they are used special means, methods and rules of interaction – interfaces. Depending on the method of data transfer, a distinction is made between parallel and serial interfaces. IN parallel interface q bits of data are transmitted over q communication lines. IN serial interface Data transmission is usually carried out over two lines: one continuously transmits clock (synchronizing) pulses from the timer, and the second carries information.

In mining machine automation systems, serial interfaces of the RS232 and RS485 standards are most often used.

The RS232 interface provides communication between two computers, a control computer and a microcontroller, or communication between two microcontrollers at speeds up to 19600 bps over a distance of up to 15m.

The RS-485 interface provides data exchange between several devices over one two-wire communication line in half-duplex mode. The RS-485 interface provides data transfer at speeds up to 10 Mbit/s. The maximum transmission range depends on the speed: at a speed of 10 Mbit/s maximum length line - 120 m, at a speed of 100 kbit/s - 1200 m. The number of devices connected to one interface line depends on the type of transceivers used in the device. One transmitter is designed to control 32 standard receivers. Receivers are available with input impedances of 1/2, 1/4, 1/8 of the standard. When using such receivers, the total number of devices can be increased accordingly: 64, 128 or 256. Data transfer between controllers is carried out according to rules called protocols. Exchange protocols in most systems operate on a master-slave principle. One device on the highway is the master and initiates the exchange by sending requests to slave devices, which differ in logical addresses. One of the popular protocols is the Modbus protocol.

2. Actuators

Execution of the decision, i.e. the implementation of the control action corresponding to the generated control signal is carried out actuators (ED). In general, an actuator is a combination of an actuator (AM) and a regulatory body (RO). The location of the actuators in the block diagram of the local ACS is shown in Figure 11.

Figure 11 - Location of actuators in the block diagram of a local automatic control system

An actuator (AM) is a device designed to convert control signals generated by the control unit (PLC) into signals convenient for influencing the final link of the ACS - the regulatory body (RO).

The actuator consists of the following basic elements:

executive motor (electric motor, piston, membrane);

clutch element (coupling, hinge);

transmission-converting element (gearbox with output lever or rod);

power amplifier (electric, pneumatic, hydraulic, combined)

In a specific MI model, a number of elements (except for the actuator motor) may be missing.

The main requirement for the IM: movement of the RO with the least possible distortion of the control laws of the generated PLC, i.e. The MI must have sufficient speed and accuracy.

Main characteristics:

a) nominal and maximum torque value

on the output shaft (rotary) or forces on the output rod;

b) the rotation time of the output shaft of the IM or the stroke of its rod;

c) the maximum value of the output shaft rotation angle or stroke

d) dead zone.

Actuators are classified according to the following signs:

1) movement of the regulatory body (rotary and linear);

2) design (electric, hydraulic, pneumatic);

Electric – with electric motor and electromagnet drives;

Hydraulic – with drives: piston, plunger, from a hydraulic motor;

Pneumatic – with drives: piston, plunger, membrane, diaphragm, from an air motor.

In practice, electrical MI is most widely used. Electrical MI are classified as:

electromagnetic;

electric motor

Electromagnetic MI are divided into:

IM with drives from electromagnetic couplings designed to transmit rotational motion (friction and sliding clutches;

IMs with a solenoid drive are 2-position devices (i.e., designed for 2-position control) that carry out translational movement of the drive elements according to the discrete principle: “on - off.”

Electric motor MI are divided into:

single-turn - the angle of rotation of the output shaft does not exceed 360 0. Example: MEO (electric single-turn mechanism). They use single-phase and three-phase (MEOK, MEOB) asynchronous motors.

multi-turn – for remote and local control pipeline fittings(valves).

In automation systems of mining machines, electric hydraulic distributors, for example the GSD and 1RP2 types, are widely used as actuators. The 1RP2 electric hydraulic distributor is designed to control the feed speed and cutting elements of the combine as part of the URAN.1M automatic load controllers and the SAUK02.2M automation system. The 1RP2 electrohydraulic distributor is a hydraulic spool valve with a pull-type electromagnetic drive.

Regulatory body (RO) is the final element of the ACS that exercises direct control influence on the OS. RO changes the flow of material, energy, mutual arrangement parts of apparatus, machines or mechanisms in the direction of the normal flow of the technological process.

The main characteristic of the RO is its static characteristic, i.e. the relationship between the output parameter Y (flow, pressure, voltage) and the stroke value of the regulator in percent.

RO provide:

a) two-position regulation - the RO gate quickly moves from one extreme position to another.

b) continuous - in this case it is necessary that the throughput characteristic of the RO be strictly defined (gate, tap, butterfly valve).

Federal Agency for Education

State educational institution

higher professional education

"Omsk State Technical University"

V.N. Gudinov, A.P. Korneychuk

TECHNICAL AUTOMATION TOOLS
Lecture notes

Omsk 2006
UDC 681.5.08(075)

BBK 973.26-04ya73

G
REVIEWERS:
N.S. Galdin, Doctor of Technical Sciences, Professor of the Department of PTTM and G, SibADI,

V.V. Zakharov, head of the automation department of ZAO NOMBUS.
Gudinov V.N., Korneichuk A.P.

G Technical means of automation: Lecture notes. – Omsk: Omsk State Technical University Publishing House, 2006. – 52 p.
The lecture notes provide basic information about modern technical and software-hardware automation tools (TSA) and software-hardware complexes (STC), the principles of their construction, classification, composition, purpose, characteristics and features of application in various automated systems ah management and regulation of technological processes (APCS).

Lecture notes are intended for students of full-time, evening, correspondence and distance learning in specialty 220301 - “Automation technological processes and production."
Published by decision of the editorial and publishing council of Omsk State Technical University.
UDC 681.5.08(075)

BBK 973.26-04ya73

© V.N. Gudinov, A.P. Korneychuk 2006

© Omsk State

Technical University, 2006

1. GENERAL INFORMATION ABOUT TECHNICAL AUTOMATION TOOLS

BASIC CONCEPTS AND DEFINITIONS
The purpose of the course “Technical Automation Tools” (TSA) is to study the elemental base of automatic process control systems. First, we present the basic concepts and definitions.

Element(device) – a structurally complete technical product designed to perform certain functions in automation systems (measurement, signal transmission, information storage, processing, generation of control commands, etc.).

Automatic control system (ACS)– set technical devices and software and hardware that interact with each other in order to implement a certain control law (algorithm).

Automated process control system (APCS)– a system designed to develop and implement control actions on a technological control object and is a human-machine system that provides automatic collection and processing of information necessary to control this technological object in accordance with accepted criteria (technical, technological, economic).

Technological control object (TOU) - totality technological equipment and implemented on it according to the relevant instructions and regulations of the technological process.

When creating modern automated process control systems, global integration and unification is observed technical solutions. The main requirement of modern automatic control systems is the openness of the system, when the data formats used and the procedural interface are defined and described for it, which allows connecting “external” independently developed devices and devices to it. Behind last years The TCA market has changed significantly, many domestic enterprises have been created that produce automation tools and systems, and systems integrators have appeared. Since the early 90s, leading foreign manufacturers of TCA began to widely introduce their products into the CIS countries through sales offices, branches, joint ventures and dealer firms.

The intensive development and rapid dynamics of the market for modern control technology require the emergence of literature reflecting the current state of TCA. Currently, the latest information about automation equipment of domestic and foreign companies is scattered and is mainly presented in periodicals or on the global Internet on the websites of manufacturing companies or on specialized information portals such as www.asutp.ru, www.mka. ru, www.industrialauto.ru. The purpose of this lecture notes is a systematic presentation of material about the elements and industrial complexes of TSA. The abstract is intended for students of the specialty “Automation of Technological Processes and Production” studying the discipline “Technical Automation Tools”.

1.1. Classification of TSA by functional purpose in ACS

In accordance with GOST 12997-84, the entire TSA complex, according to their functional purpose in the ACS, is divided into the following seven groups (Fig. 1).

Rice. 1. Classification of TSA by functional purpose in ACS:

CS – control system; OU – control object; CS – communication channels;

Memory – master devices; UPI – information processing devices;

USPU – amplifying and converting devices; UIO – information display devices; IM – actuators; RO – working bodies; KU – control devices; D – sensors; VP – secondary converters

1.2. TCA development trends
1. Magnification functionality TCA:

– in the control function (from the simplest start/stop and automatic reverse to cyclic and numerical program and adaptive control);

– in the alarm function (from the simplest light bulbs to text and graphic displays);

– in the diagnostic function (from open circuit indication to software testing of the entire automation system);

– in the function of communication with other systems (from wired communications to networked industrial facilities).

2. Complication of the element base means a transition from relay contact circuits to contactless circuits on semiconductor individual elements, and from them to integrated circuits of increasing degrees of integration (Fig. 2).

Rice. 2. Stages of development of electric vehicles
3. Transition from rigid (hardware, circuit) structures to flexible (reconfigurable, reprogrammable) structures.

4. Transition from manual (intuitive) TCA design methods to machine, scientifically based computer-aided design (CAD) systems.

1.3. TCA imaging methods
In the process of studying this course, various methods of depicting and presenting TCA and their components. The most commonly used are the following:

1. Constructive method(Fig. 7-13) involves depicting instruments and devices using methods mechanical engineering drawing in the form of technical drawings, layouts, common types, projections (including axonometric ones), sections, cuts, etc. .

2. Circuit method(Fig. 14.16-21.23) assumes, in accordance with GOST ESKD, the representation of TSA with circuits of various types (electrical, pneumatic, hydraulic, kinematic) and types (structural, functional, fundamental, installation, etc.).

3. Mathematical model is used more often for software-implemented TSA and can be represented by:

– transfer functions of typical dynamic links;

– differential equations of ongoing processes;

– logical functions for controlling outputs and transitions;

– state graphs, cyclograms, time diagrams (Fig. 14, 28);

– block diagrams of functioning algorithms (Fig. 40), etc.
1.4. Basic principles of TCA construction
To build modern automated process control systems, a variety of devices and elements are required. Satisfying the needs of control systems of such different quality and complexity for automation equipment with their individual development and production would make the problem of automation immense, and the range of instruments and automation devices almost limitless.

At the end of the 50s, the USSR formulated the problem of creating a unified State System of Industrial Instruments and Automation Equipment (GSP)– representing a rationally organized set of instruments and devices that satisfy the principles of typification, unification, aggregation, and intended for the construction of automated systems for measuring, monitoring, regulating and managing technological processes in various industries. And since the 70s, GSP has also covered non-industrial areas of human activity, such as scientific research, testing, medicine, etc.

Typing- this is a reasonable reduction of the variety of selected types, designs of machines, equipment, devices, to a small number of the best samples from any point of view, which have significant qualitative characteristics. During the typification process, standard designs are developed and installed, containing basic elements and parameters common to a number of products, including promising ones. The typification process is equivalent to grouping, classifying some initial, given set of elements into a limited number of types, taking into account actual restrictions.

Unification– this is the reduction of various types of products and means of their production to a rational minimum of standard sizes, brands, shapes, properties. It brings uniformity to the main parameters standard solutions TCA also eliminates the unjustified variety of means of the same purpose and the diversity of their parts. Devices, their blocks and modules, identical or different in their functional purpose, but derived from one basic design, form a unified series.

Aggregation is the development and use of a limited range of standard unified modules, blocks, devices and unified standard structures (UTC) for the construction of many complex problem-oriented systems and complexes. Aggregation allows you to create various modifications of products on the same basis, to produce TSA for the same purpose, but with different technical characteristics.

The principle of aggregation is widely used in many branches of technology (for example, modular machines and modular industrial robots in mechanical engineering, IBM-compatible computers in control systems and automation of information processing, etc.).

2. STATE INDUSTRIAL DEVICES SYSTEM

AND AUTOMATION MEANS

GSP is a complex developing system consisting of a number of subsystems that can be viewed and classified from different positions. Let's consider the functional-hierarchical and constructive-technological structure of technical means of GSP.
2.1. Functional-hierarchical structure of SHGs

Rice. 3. Hierarchy of SHGs
Distinctive Features modern structures building automated control systems industrial enterprises are: the penetration of computing tools and the introduction of network technologies at all levels of management.

In world practice, specialists in integrated production automation also distinguish five levels of management modern enterprise(Fig. 4), which completely coincides with the above hierarchical structure of the SHG.

At the level ER.P.– Enterprise Resource Planning (enterprise resource planning) calculates and analyzes financial and economic indicators, and solves strategic administrative and logistics problems.

At the level MES– Manufacturing Execution Systems (production execution systems) – tasks of product quality management, planning and control of the sequence of operations of the technological process, management of production and human resources within the framework of the technological process, maintenance of production equipment.

These two levels relate to the tasks of automated control systems (automated enterprise management systems) and the technical means with the help of which these tasks are implemented are office personal computers(PC) and workstations based on them in the services of the chief specialists of the enterprise.


Rice. 4. Pyramid of modern production management.
At the next three levels, problems that belong to the class of automated process control systems (automated process control systems) are solved.

SCADA– Supervisory Control and Data Acquisition (data collection and supervisory (dispatcher) control system) is a level of tactical operational management at which problems of optimization, diagnostics, adaptation, etc. are solved.

Control- level– level of direct (local) control, which is implemented on such TCAs as: software – operator panels (remotes), PLCs – programmable logic controllers, USO – communication devices with the object.

HMI– Human-Machine Interface (human-machine communication) – visualizes (displays information) the progress of the technological process.

Input/ Output– The inputs/outputs of the control object are

sensors and actuators (S/AM) of specific technological installations and working machines.

2.2. Structural and technological structure of GSP


Rice. 5. SHG structure
UKTS(unified set of technical means) – it's a collection different types technical products, designed to perform various functions, but built on the basis of the same operating principle and having the same structural elements.

ACTS(aggregate complex of technical means) – This is a set of different types of technical products and devices, interconnected by functionality, design, type of power supply, level of input/output signals, created on a single design, software and hardware basis according to the block-modular principle. Examples of well-known domestic UKTS and ACTS are given in Table. 1.

PTK ( software and hardware complex ) – This is a set of microprocessor automation tools (programmable logic controllers, local regulators, communication devices with the object), display panels of operators and servers, industrial networks interconnecting the listed components, as well as industrial software of all these components, designed to create distributed automated process control systems in various industries. Examples of modern domestic and foreign hardware and software systems are given in Table. 2.

Specific complexes of technical means consist of hundreds and thousands of different types, sizes, modifications and designs of instruments and devices.

Product type- this is a set of technical products that are identical in functionality, have a single operating principle, and have the same nomenclature of the main parameter.

Standard size- products of the same type, but having their own specific values main parameter.

Modification- is a collection of products of the same type that have certain design features.

Execution– design features that affect performance characteristics.

TCA complexes Table 1