Functional diagram of automatic monitoring and control
is intended to display the main technical solutions,
accepted when designing process automation systems
processes. Control object in process automation systems
processes is a combination of main and auxiliary
equipment along with built-in shut-off and regulating
organs.
A functional diagram is a technical document defining
functional block structure of individual nodes of automatic
control, management and regulation of the technological process and
equipping the control facility with instruments and automation equipment. On
The functional diagram shows automatic control systems,
regulation, remote control, alarm, protection and
blocking.
All elements of control systems are shown in the form of conditional
images and are combined into a single system by lines of functional
communications. Functional diagram of automatic monitoring and control
contains a simplified image of the technological diagram
automated process. The equipment in the diagram is shown in the form of symbolic images.
In accordance with GOST 36-27-77 “Instruments and automation equipment. Conventional designations in technological process automation schemes" establishes the designations of measured quantities, functional characteristics of devices, communication lines, as well as methods and techniques for constructing conventional graphic designations of devices and automation equipment.
When developing a functional diagram of process automation, it is necessary to solve the following problems:
The task of obtaining primary information about the state of the technological process and equipment;
The task of directly influencing the technological process to control it and stabilize the technological parameters of the process;
The task of monitoring and recording technological parameters of processes and the state of technological equipment.
When developing a functional diagram, determine:
1) an appropriate level of automation of the technological process;
2) principles of organizing control and management of technological
process;
3) technological equipment controlled automatically,
remotely or in both modes according to the operator’s instructions;
4) list and values of controlled and adjustable parameters;
5) control methods, laws of regulation and management;
6) the scope of automatic protection and blocking of autonomous control circuits of technological units;
7) a set of technical automation equipment, the type of energy for transmitting information;
8) locations of equipment on technological equipment, on switchboards and control panels.
The automation scheme must be drawn up in such a way that it can be easily determined from it:
1) technological process parameters that are subject to automatic control and regulation;
2) availability of protection and alarm;
3) accepted mechanism locking;
4) organization of control and management points;
5) the functional structure of each control, alarm, automatic regulation and control unit;
6) technical means with the help of which one or another functional unit of control, alarm, automatic regulation and control is implemented.
In accordance with the recommendations of GOST 2.702-75 “Rules for the execution of electrical circuits,” the graphic construction of the circuit should give a clear idea of the sequence of interaction of functional parts in the system. A functional diagram should depict the functional parts of the product (elements, devices and functional groups) involved in the process illustrated by the diagram, and the connections between these parts.
There are two generally accepted options for presenting a functional diagram:
according to GOST 21.404-85 “Automation of technological processes. Symbols of devices and automation equipment in diagrams" and GOST 21.408-93 "System of design documentation for construction. Rules for the implementation of working documentation for automation of technological processes";
according to the American Society of Instrument Makers Standard ANSI/ISA S5.1. "Instrumetation Symbols and Identification".
An example of the application of GOST is the instrumentation and automation diagram given in the appendix of GOST 21.408-93 (Fig. 6). This diagram shows:
Channel for converting information from the sensitive element 7a into a unified signal 7b;
Channel for converting the control signal 7c into a control action on the actuator (valve) 7i with the ability to control it from the remote control panel 7e, indicating the position of the key and using the manual control key 7g;
Alarm channel 7d with light signals HL1/2.
In the block cabinet (for example, in the relay automation cabinet), the measurement signal is converted for remote transmission. Monitoring and manual (controller) control are carried out at the operator panel. The control loop is closed by the actuator.
Monitoring, control and configuration of the speakers are carried out on the control level screens (lower part of the diagram).
It is important for signals on the diagram to indicate the dimension and measurement limits of physical parameters: mm, o C, MPa, m 3 / hour, etc.
Fig.6 Example of a functional diagram of automation according to GOST
The functional parts and connections between them are depicted in the diagram in the form of conventional graphic symbols established in the standards of the Unified System of Design Documentation. The semantics of the abbreviation KIPiA plays a special role here. The recommended way to build a naming system for instrumentation and automation, established in GOST, is to form a multi-letter name, the first position of which can be any of the 20 letters of the Latin alphabet, the second - any of 5 letters, the third - any of 7, etc. (for example, LIR, where L is level; I is readings; R is registration).
An example of the application of the ANSI standard is the instrumentation diagram shown in Fig. 7.
In this figure, 4 levels of AC can be distinguished: the lower level is the pump motor, the level of panel devices - YSLH and YS, the level of blocking and control logic, and the upper level - signaling the state of the executive and command elements of the automation system.
The ESD motor protection and control unit provides:
Soft start of the engine;
Engine reverse;
Braking with a given current for a given time;
Current limitation during starting, driving and braking;
Control by discrete signals, via a serial interface, from a local control station;
Load disconnection in case of short circuit;
Timer shutdown;
Checking the presence of electric motor phases at specified intervals and issuing warnings when stopped;
Determining changes in phase sequence when the unit is turned on and issuing warnings;
Determining the failure of one of the network phases below the set level and issuing a warning;
Adjusting the opening angle of thyristors using an analog input signal.
The pump status is indicated by the YSLH control panel. This signal generates the YSL blocking logic, which is then reflected by the YAL stop warning alarm and the YLH run alarm.
Based on the state of the YS panel switch, the motor relay control logic is generated, which is reflected by the YL alarm.
Based on the state of the YS key, the ESD voltage generator is turned on remotely, which is confirmed by the “Locking triggered” indication LA. Communication with the primary and secondary devices is shown by dotted lines.
Process monitoring and control systems often use combined and complex devices, such as
Fig. 8 Example of a panel part of a spaced version of a functional diagram
combined measuring and control instruments,
microprocessors, computers, remote control semi-kits, etc. Such devices are designated by a rectangle of arbitrary dimensions indicating inside the rectangle (Fig. 8) the type of device (U - several heterogeneous measured quantities; Y - transformations and computational functions; I - readings; R - registration; C - control; S - on, off, switching, blocking; A-signaling).
All instrumentation and automation devices depicted on the functional automation diagram are assigned positional designations consisting of two parts: Arabic numerals - the number of the functional group and lowercase letters of the Russian alphabet - the number of instrumentation and automation equipment in this functional group (for example, 5a, 3b, etc.).
Letter designations are assigned to each element of the functional group in alphabetical order depending on the sequence of signal passage - from devices for receiving information to devices influencing the controlled process (for example, a primary measuring device, a secondary converter, a set pointer, a regulator, a position indicator, an actuator, a regulating body) .
It is allowed to use Arabic numbers instead of letters of the Russian alphabet (for example, 5-1, 3-2, etc.).
Positional designations of individual instruments and automation equipment, such as a direct-acting regulator, pressure gauge, thermometer, etc., consist only of serial numbers.
When determining the boundaries of each functional group, the following circumstance must be taken into account: if any device or controller is connected to several sensors or receives additional influences based on other parameters (for example, a correction signal), then all circuit elements that perform additional functions belong to that functional group , which is affected. In particular, the ratio regulator is part of the functional group that is influenced by the independent parameter.
In centralized control systems using computer technology, in telemetry systems, as well as in complex automatic control schemes with devices common to different functional groups, all common elements are placed into independent functional groups.
Positional designations are usually placed at the bottom of the circle indicating the device, or next to it on the right side, or above it.
Related information.
In general, the block diagram of a single-circuit automatic control system is presented in Figure 1.1. An automatic control system consists of an automation object and a control system for this object. Thanks to a certain interaction between the automation object and the control circuit, the automation system as a whole provides the required result of the operation of the object, characterizing its output parameters and characteristics.
Every technological process is characterized by certain physical quantities (parameters). For the rational progress of the technological process, some of its parameters must be maintained constant, and some must be changed according to a certain law. When operating an object controlled by an automation system, the main task is to maintain rational conditions for the technological process.
Let's consider the basic principles of constructing the structures of local automatic control systems. With automatic control, as a rule, three types of problems are solved.
The first type of task includes maintaining one or more technological parameters at a given level. Automatic control systems that solve problems of this type are called stabilization systems. Examples of stabilization systems include systems for regulating temperature and humidity in air conditioning units, pressure and temperature of superheated steam in boiler units, speed control in steam and gas turbines, electric motors, etc.
The second type of task involves maintaining correspondence between two dependent or one dependent and other independent quantities. Systems that regulate ratios are called automatic tracking systems, for example, automatic systems for regulating the “fuel - air” ratio in the process of fuel combustion or the ratio “steam flow - water flow” when feeding boilers with water, etc.
The third type of problem involves changing a controlled variable over time according to a certain law. Systems that solve this type of problem are called program control systems. A typical example of this type of system is a temperature control system during heat treatment of metal.
In recent years, extreme (search) automatic systems have been widely used, providing the maximum positive effect of the functioning of a technological object with minimal costs of raw materials, energy, etc.
A set of technical means with the help of which one or more regulated quantities, without the participation of a human operator, are brought into conformity with their constant or specified values varying according to a certain law by generating an impact on the regulated quantities as a result of comparing their actual values with the given ones, is called an automatic control system ( ACP) or automatic control system. From the definition it follows that, in general, the simplest ASR should include the following elements:
control object (OU), characterized by a controlled variable x n. x(t);
a measuring device (MD) that measures the controlled variable and converts it into a form convenient for further conversion or for remote transmission;
a master device (SD), in which a setpoint signal is installed that determines the set value or the law of change of the controlled variable;
a comparison device (CD), in which the actual value of the controlled variable x is compared with the prescribed value g(t) and,
deviation is detected (g(t)- x(t));
a control device (RU), which generates, upon receipt of a deviation (ε) at its input, a regulatory action that must be applied to the controlled object in order to eliminate the existing deviation of the controlled quantity x from the prescribed value g(t);
actuator mechanism (AM). At the output of the reactor plant, the regulating effect has a small power and is issued in a form that is generally not suitable for direct influence on the object of regulation. It is necessary to either strengthen the regulatory impact or transform it into a convenient form x p. For this purpose, special actuators are used, which are the actuator output devices of the regulating element;
regulatory authority (RO). Actuators cannot directly influence the controlled variable. Therefore, the objects of regulation are equipped with special regulatory bodies RO, through which the IM influences the regulated variable;
communication lines through which signals are transmitted from element to element in an automatic system.
As an example, let's consider a larger block diagram of automatic control (Figure 1.1). In the diagram, the output parameters - the result of the operation of the controlled object, are designated x 1, x 2, ……… x n. In addition to these main parameters, the operation of automation objects is characterized by a number of auxiliary parameters (y 1, y 2,.......y n), which must be monitored and regulated, for example, maintained constant.
Figure 1.1. Block diagram of automatic control
During operation, the control object receives disturbing influences f1.... fn, causing deviations of parameters x1.......xn from their rational values. Information about the current values x tek and y tek enters the control system and is compared with their prescribed values (setpoints) g1...... gn, as a result of which the control system exerts control actions E1.....En on the object, aimed at compensating for deviations of the current output parameters from the given values.
According to the structure of automatic control systems for an automation object, in particular cases they can be single-level centralized, single-level decentralized and multi-level. At the same time, single-level control systems are systems in which the object is controlled from one control point or from several independent ones. Single-level systems in which control is carried out from one control point are called centralized. Single-level systems, in which individual parts of a complex object are controlled from independent control points, are called decentralized.
2.2 Functional and technological diagrams of automatic control
Functional-technological diagram is the main technical document that defines the functional block structure of the devices of the units and elements of the automatic control system, regulation of the technological process (operations) and control of its parameters, as well as equipping the control object with devices and automation equipment. Schemes are also often called simply automation schemes. The composition and rules of implementation are dictated by the requirements of the standards (see Chapter 1).
The functional and technological automation diagram is carried out in one drawing, on which the symbols depict technological equipment, transport lines and pipelines, instrumentation and automation equipment, indicating the connections between them. Auxiliary devices (power supplies, relays, circuit breakers, switches, fuses, etc.) are not shown on the diagrams.
Functional automation diagrams are related to production technology and technological equipment, therefore the diagram shows the placement of technological equipment in a simplified manner, without respect to scale, but taking into account the actual configuration.
In addition to technological equipment, functional automation diagrams in accordance with standards depict transport lines for various purposes in a simplified (two-line) and conventional (single-line) manner.
Both the construction and study of technical documentation diagrams must be carried out in a certain sequence.
Process parameters that are subject to automatic control and regulation;
Functional management structure;
Control loops;
Availability of protection and alarm and accepted mechanism locking;
Organization of control and management points;
Technical means of automation, with the help of which the functions of control, alarm, automatic regulation and control are solved.
To do this, you need to know the principles of constructing automatic control systems for process control and conventional images of process equipment, pipelines, instruments and automation equipment, functional connections between individual devices and automation equipment, and have an idea of the nature of the technological process and the interaction of individual installations and units of process equipment.
In a functional diagram, communication lines and pipelines are often shown in a single-line diagram. The designation of the transported medium can be either digital or alphanumeric. (For example: 1.1 or B1). The first number or letter indicates the type of transported medium, and the subsequent number indicates its purpose. Numerical or alphanumeric designations are presented on the shelves of leader lines or above the transport line (pipeline), and, if necessary, in breaks in the transport lines (in this case, the accepted designations are explained in drawings or in text documents (see table 1.1.). On technological objects show those control and shut-off valves, technological devices that are directly involved in monitoring and controlling the process, as well as sampling (sensors), shut-off and regulatory bodies necessary to determine the relative location of sampling points (locations for installing sensors), as well as measurement or control parameters (see table 1.2).
Complete devices (centralized control machines, control machines, semi-sets of telemechanics, etc.) are designated by a rectangle of arbitrary sizes with the type of device indicated inside the rectangle (according to the manufacturer’s documentation).
In some cases, some elements of technological equipment are also depicted on diagrams in the form of rectangles, indicating the names of these elements. In this case, next to sensors, selective, receiving and other devices similar in purpose, indicate the name of the technological equipment to which they belong.
Table 1.1. Designation of transport pipeline lines according to GOST 14.202 – 69
| Contents of transport lines (pipelines) | Conventional digital and letter designation | Designation in color |
| Liquid or gas (general) | - | Red Yellow |
| Water Steam Air Oxygen | - 1.1 - 1.0 - - 2.1 - 2.0 - - 3.1 - 3.6 - - 3 - 7 - | Green Pink Light Blue |
| Noble gases | - 5.1-5.0 - | Violet |
| Ammonia Acid (oxidizing agent) Alkali Oil Liquid fuel | - 11 - 11 - - 3 - 7 - - 7.1-7.0 - -8.4 – 14 – - 8.6 - | Gray Olive Gray-brown Brown Yellow |
| Flammable and explosive gases | -16 – 16 - | Orange |
| Water pipes | VO – B9 | - |
| Fire pipeline | AT 2 | Light gray |
| Sewerage | KO – K12 | - |
| Heat pipe | TO – T8 | - |
Table 1.2. Symbols of technological fittings
| Name | Designation according to GOST 14.202 - 69 |
| Shut-off valve through passage (gate valve) |  |
| Electrically operated valve |  |
| Three way valve |  |
| safety valve |  |
| Rotary valve (valve, gate) |  |
| Actuator diaphragm |  |
| Table 1.3. Output electrical switching elements | |
| Name | Designation according to GOST 2.755 - 87 |
| Contact for switching high current circuit (contactor contact) |  |
| Normal contact |  |
| Normal contact |  |
To make diagrams easier to read, arrows are placed on pipelines and other transport lines indicating the direction of movement of the substance.
In the functional-technological diagram, as well as in the image of the pipeline through which the substance leaves this system, a corresponding inscription is made, for example: “From the absorption workshop”, “From the pumps”, “To the polymerization circuit”.
Figure 1.2. Image of sensors and sampling devices (fragment)
Conventional graphic symbols of automation equipment are given in tables 1.2., 1.3., 1.4.. Conventional graphic symbols of electrical equipment used in functional automation diagrams should be depicted in accordance with the standards (Table 1.3.). If there are no standard symbols for any automatic devices, you should adopt your own symbols and explain them with an inscription on the diagram. The thickness of the lines of these designations should be 0.5 - 0.6 mm, except for the horizontal dividing line in the symbolic image of the device installed on the switchboard, the thickness of which is 0.2 - 0.3 mm.
The sampling device for all permanently connected devices does not have a special designation, but is a thin solid line connecting the process pipeline or apparatus with the device (Fig. 1.2. devices 2 and 3a). If it is necessary to indicate the exact location of the sampling device or measurement point (inside the graphic designation of the technological apparatus), a circle with a diameter of 2 mm is depicted in bold at the end (Fig. 1.2 devices 1 and 4a).
Table 2.4. Conventional graphic symbols of automation equipment and devices
| Name | Symbol according to GOST 21.404 - 85 |
| Primary measuring transducer (sensor) or device installed locally (on a production line, apparatus, wall, floor, column, metal structure). Basic Acceptable | |
| Device installed on a panel, console Basic Permissible | |
| Sampling device without permanent connection of the device | |
| Actuating mechanism | |
| Track switch | |
| Electric bell, siren, horn |  |
| Electric heater: a) resistance, c) induction |  |
| Recording device | |
| Incandescent lamp, gas discharge (signal) | |
| Three-phase electric machine (M – motor, G – generator) |  |
| DC electric machine (motor M, generator G) |  |
To obtain a complete (freely readable) designation of a device or other automation device, a letter symbol is entered into its conventional graphic image in the form of a circle or oval, which determines the purpose, functions performed, characteristics and operating parameters. In this case, the location of the letter determines its meaning. Thus, the letters given in Table 1.5 are the main parameters and functions, and the letters given in Table 1.6 specify the function or parameter.
Table 1.5. Designation of the main measured parameters in automation schemes
| Measured parameter | Designation |
| Density | D |
| Any electrical quantity. To specify the electrical quantity being measured, to the right of the conventional graphic image of the device it is necessary to give its name, for example, voltage, current, power, etc. | E U, I, P |
| Consumption | F |
| Size, position, movement | G |
| Time, time program | K |
| Level | L |
| Humidity | M |
| Pressure, vacuum | P |
| Composition, concentration, etc. | Q |
| Speed, frequency | S |
| Temperature | T |
| Viscosity | V |
| Weight | W |
| Several heterogeneous measured quantities | U |
To designate manual control, the letter H is used. To designate quantities not provided for by the standard, reserve letters can be used: A, B, C, I, N, O, Y, Z (the letter X is not recommended). The reserved letters used must be deciphered by the inscription on the free field of the diagram.
Below are the designations for clarifying values of the measured quantities.
Table 1.6. Additional letter designations
The letter used to clarify the measured value is placed after the letter indicating the measured value, for example P, D - pressure difference.
The functions performed by devices for displaying information are indicated in Latin letters (see Table 2.7).
Table 1.7. Letter designation of function
Additionally, designations with the letters E, G, V can be used.
All of the above letter designations are placed in the upper part of the circle indicating the device (device).
If several letters are used to designate one device, then the order of their arrangement after the first one, indicating the measured value, should be, for example: TIR - a device for measuring and recording temperature, PR - a device for recording pressure.
When designating devices made in the form of separate blocks and intended for manual operations, the letter H is placed first.
For example in Fig. 1.2 shows an automation diagram using recording instruments for temperature and pressure difference, where to form a symbol for the device (set), the functional purpose is indicated in the upper part of the circle, and its position designation is placed in the lower part of the circle (alphabetic - digital or digital - 1, 2, 4a, 4b, 3a, 3b). Thus, all elements of one set, i.e. one functional group of devices (primary, intermediate and transmitting measuring transducers, measuring device, regulating device, actuator, regulating body) are designated by the same number. In this case, the number 1 is assigned to the first (from the left) set, the number 2 to the second, etc.
To distinguish the elements of one set, a letter index is placed next to the number (the letters Z and O, the outline of which is similar to the outline of numbers, are not recommended): for the primary transducer (sensitive element) - index “a”, for the transmitting transducer - “b” , at the measuring device - “in”, etc. Thus, for one set the full designation of the primary measuring transducer will be 1a, transmitting measuring transducer 1b, measuring (secondary) device 1c, etc. the height of the number is 3.5 mm, the height of the letter is 2.5 mm.
Methodology for drawing up a functional and technological automation diagram.
The functional diagram is the main technical document that determines the structure and nature of the automation of the technological process of the designed facility and its equipping with instruments and automation equipment.
The functional diagram conventionally depicts technological equipment, communications, controls, instruments and automation equipment, as well as connections between them.
An example of a drawing of a functional automation diagram is shown in Fig. 2.
When designing and describing functional diagrams, the terminology must comply with GOST 17194-71, and the symbols of devices and automation equipment - GOST 3925-59.
If there are technological objects of the same type (workshops, departments, installations, units, devices), not interconnected and having the same equipment with instruments and automation equipment, a functional diagram is made for one of them, and an explanation is given on the drawing, for example, “The diagram is drawn up for unit 1; for units 2-5 the schemes are similar.” To this are added explanations regarding the features in the designations (markings) and in the specification. For example, “The specification takes into account equipment for five units. The marking of instruments and automation equipment for units 2-5 is similar to that shown for unit 1, with the digital index changing according to the unit number.”
To indicate on the diagrams the designed telecontrol (TC), telesignaling (TS) and telemetering (TI) systems, horizontal lines are drawn in the rectangles of boards and (control panels) with inscriptions on the left side TU, TS, TI. The connection of these systems with devices and automation equipment is shown by lines communications. Technological equipment and communications of an automated object are depicted in functional diagrams in a simplified manner, but in such a way as to show their relative location and interaction with devices and automation equipment. It is allowed to depict parts of the object in the form of rectangles with their names indicated on technological communications (they are depicted according to GOST. 3464-63) show only those regulating and shut-off bodies that are involved in the process control system. The diameters of the nominal passages are indicated on the pipeline lines and the directions of the flow of the substance are indicated by arrows in accordance with the technological diagram.
Instruments and automation equipment built into technological equipment and communications or mechanically connected to it are depicted on functional diagrams in close proximity to the technological equipment. These include: selecting devices for pressure, level, composition of the substance, receiving devices that perceive the effects of measured and controlled quantities (restrictive devices, rotameters, resistance thermometers, thermal cylinders of manometric thermometers, thermocouples, etc.), actuators, control and shut-off elements .
Instruments and automation equipment that do not have a direct structural and mechanical connection with process equipment are shown in rectangles located at the bottom of the drawing field. These include: primary transducers (sensors), working in conjunction with selective devices, converters, amplifiers; instruments and control equipment, etc. . They are located on the diagram in one or several horizontal rows and are conventionally limited to rectangles.
The rectangle on the left indicates their names: “Local devices”, “Control panel”, etc. Auxiliary equipment and devices (filters and pneumatic supply gearboxes, fuses, magnetic starters, etc.) that do not affect the functional structure of the automation circuit , are not shown on the diagrams.
The exception is magnetic starters used in control loops to control actuators. The devices on the switchboards are shown in the diagram conventionally in the lower rectangle; local devices are located above it.
Communication lines on a functional diagram are depicted as one line, depending on the number of wires and pipes making this connection, and are drawn with the least number of kinks and intersections. Communication lines must clearly display the functional connections between circuit elements from the beginning of the signal to the end. It is allowed to combine blocking communication lines into one common line. In order to make it easier to read functional automation diagrams with a large amount of technological equipment and automation equipment, under the rectangles of switchboards and consoles, it is allowed to draw a rectangle with inscriptions explaining the purpose of the depicted automation equipment.
On the diagrams, all devices and automation equipment are assigned positional designations.
The designations clearly identify the type and location of installation of the device. Each set of automation equipment is assigned a serial number (for example, set 1 in Fig. 2). A set is considered to be functionally related devices that perform a specific task. Each device in the kit is assigned an alphanumeric designation, consisting of the serial number of the kit and a letter index.
In the drawings of functional diagrams, on the right side above the stamp of the drawing, a specification (one of the options for implementing the diagrams) is placed, which is the source material for drawing up application forms and order specifications. If the project provides for the use of new technological equipment, then its specification is placed first, then the specification for automation equipment is placed, and in the groups “local devices”, “devices on switchboards”.
The specification includes all devices that are assigned position designations on the diagrams.
Designations of basic quantities and symbolic images of devices and automation equipment in diagrams.
GOST 3925-59 establishes the designations of measured and controlled quantities and symbolic images of instruments and automation devices used in functional diagrams. These include designations of the main controlled and controlled quantities, names of the main electrical measuring instruments, as well as images of measuring and control devices, types of remote control transmissions, primary transducers that perceive the influence of measured or controlled quantities, actuators and regulatory bodies, additional devices and recommended image sizes devices and means.
GOST provides examples of the use of conventional images of devices, direct-acting regulators, control devices consisting of several links, and designations of controlled and controlled quantities, as well as an example of an image of a functional automation diagram.
The automation diagram for the development of a process control system is a kind of integrated functional diagram of a technological control object, covering the so-called “field equipment” of the lower level of the system and showing its connections with instruments, control computer equipment and monitoring and control points of a higher level.
The automation scheme is carried out taking into account the requirements of section 2 of GOST 2.702-75* ESKD, clause 2.4 of GOST 24.302-80, section 4.1 of RD 50-34.698-90 and section 4.3 of GOST 21.408-93 SPDS.
The automation scheme is developed as a whole for the technological control object of the automatic control system or for a separate engineering system (power supply, heat supply, ventilation, etc.) or part of the technological/engineering system, process and operation: line, section, block, installation, unit.
Example: functional diagram of steam boiler automationThe functional diagram is developed on the basis of the initial materials for the creation of process control systems and, first of all, the materials of the technological regulations or individual documents included in the “technological regulations”.
The best option for a functional diagram of TOU automation is a diagram combined with a connection diagram, which is made as part of the main set of grade T in accordance with GOST 21.401-88 SPDS or with connection diagrams of engineering systems.
The implementation of a combined scheme is allowed in clause 3.3 of GOST 21.404-88 “Production technology. Basic requirements for working drawings."
In foreign practice, the development of PID circuits (Process Instrument Diagram) is used. The development of a combined scheme by specialists in technological processes (technological equipment, OV, VK, EM, etc.) together with specialists in the development of process control systems (including the lower, “field” level) provides the most effective solutions in both parts of the project (for example, TX and ATX).
Since such a diagram is issued with two signatures (TX and ATX), any change in part of the TX automatically becomes the property of the ATX developers, which eliminates many conflict situations that arise when documents are issued separately - separate TX connection diagrams (OV, VK, etc. .) and separately ATX automation circuits.
The automation scheme (AS), when developed separately from the release of the TX (AV, VK, etc.) sniffing scheme, must be agreed upon with the relevant specialists of the technological (plumbing, heating and ventilation, etc.) part of the project.
It should be noted that in the connection diagram (TX, OV, VK) in accordance with clause 3.2 of GOST 1 1 -88, “... pipelines and their elements” with all alphanumeric designations must be indicated.
Here are some explanations of some terms.
Technological block- a complex or assembly unit of technological equipment of a given level of factory readiness and manufacturability, intended for the implementation of main or auxiliary technological processes. The unit includes machines, apparatus, primary monitoring and control equipment, pipelines, support and service structures, thermal insulation and chemical protection.
Blocks, as a rule, are formed to carry out heat transfer, mass transfer, hydrodynamic, chemical and biological processes. The nomenclature of blocks is established by departmental regulatory documents agreed with the ministries carrying out installation work.
Process pipeline- a pipeline designed to transport various substances necessary for conducting a technological process or operating equipment.
Pipeline elements- branch pipes (pipes), bends, transitions, tees, flanges, compensators, shut-off, control, safety valves, supports, gaskets and fasteners, devices installed on pipelines for monitoring and control, condensation and other parts and devices.
Devices installed on pipelines for monitoring and control are shown as pipeline elements on a wiring diagram or combined diagram.
Alphanumeric designations are placed on the shelves of leader lines and correspond to the drawing number of the element.
Element (embedded element)- this is a part or assembly unit that is inextricably built into technological devices and pipelines (boss, fitting, pocket, sleeve, etc.).
In accordance with SNiP 3.05.07-85 “Automation Systems”, such an element is called an embedded structure or an embedded element.
The embedded structure or embedded element must ensure the necessary tightness of the process equipment and pipeline before installing the automation device on them. This allows hydraulic and pneumatic testing of equipment and pipelines to be carried out before the installation of automation devices, before the start of installation and commissioning of automation systems and process control systems.
Selection device- a device installed on technological equipment or a pipeline and designed to supply the measured medium to measuring instruments or measuring transducers (sensors).
Note that according to clause 2.12 of SNiP 3.05.07-85, embedded elements or structures for the installation of primary devices, for the installation of selective pressure, flow and level devices, etc. (ending with shut-off valves), individual flow meters, flow meters, control and shut-off elements, bypass lines (bypasses), materials for the manufacture of embedded elements (structures) are provided and specified in the technological part of the project (TX, OV, VK).
A block diagram (according to GOST) is a diagram that defines the main functional parts of an automation system, their purpose and relationships. Skeletal block diagrams are often drawn up for automatic systems.
The automation block diagram is intended to determine the monitoring and control system of the technological process of a given facility and to establish connections between switchboards and control panels, units, and operator workstations. The structural diagram is the main project document, which establishes the optimal channels of administrative, technical and operator management. They reflect the features of TP and TSA when creating local control and automation systems.
The block diagram in general reflects the complex of technical automation equipment used, the principle of interaction of the technological object with the control device and operating personnel.
We will construct the structure of the control system of the press for casting shoe bottoms based on the control loops of individual technological parameters. Construction of a block diagram in a general form will make it possible to clarify it when choosing a TSA and the layout of the selected equipment.
On this equipment, two control objects can be distinguished: OU1 - mold, OU2 - injection molding system.
For the first object, it is necessary to control the position (Figure 2.1 DP1, DP2) and temperature of the mold (Figure 2.1 DT1).
In OU2 we highlight the following parameters: temperature in three heating zones (Figure 2.1 DT2, DT3, DT4), melt pressure (Figure 2.1 DS1), thermoplastic elastomer level in the loading hopper (Figure 2.1 DS1), screw rotation speed during the cycle (Figure 2.1 DS1 ).
Electrical signals from measuring transducers are sent to the control device. The most promising would be to use an industrial controller. The presence of built-in memory (RAM), timers, counters, many discrete and analog inputs and outputs, the ability to connect additional modules that expand the possibilities of use, a unified output signal - all this speaks in favor of using an industrial controller.
The part of the block diagram showing the devices influencing the technological object has a general view and is presented in the form of 9 power converters (PR1 - PR9) and 9 actuators (IM1 - IM9).
IM1 - mold drive;
ММ2 - ejector drive;
IM3 - voltage regulator supplied to the heating elements of the mold;
ММ4 - cooling system engine;
IM5, IM6, IM7 - voltage regulator supplied to the heating elements of the injection molding system;
IM8 - screw rotation motor;
IM9 - valve for supplying the melt to the mold.
Power converters are necessary to convert the control signal of an industrial controller into a power signal that acts directly on the IM.
The block diagram also shows the control panel (CP), the alarm unit (ALS) and the presence of a communication channel with the enterprise’s automated control system.
The block diagram is shown in Figure 2.1
Figure 2.1 - Block diagram of automation