ME connection diagrams with several network interfaces. Device and design, technical characteristics, maintenance. Designations in electrical diagrams

Content:

Each electrical circuit consists of many elements, which, in turn, also include various parts in their design. The most striking example is household appliances. Even an ordinary iron consists of a heating element, a temperature regulator, a control light, a fuse, a wire and a plug. Other electrical appliances have an even more complex design, supplemented by various relays, circuit breakers, electric motors, transformers and many other details. Between them is created electrical connection, which ensures the full interaction of all elements and the fulfillment by each device of its purpose.

In this regard, the question very often arises of how to learn to read electrical circuits, where all components are displayed in the form of conditional graphic symbols. This problem is of great importance for those who regularly encounter electrical installations. Proper reading of the diagrams makes it possible to understand how the elements interact with each other and how all work processes proceed.

Types of electrical circuits

In order to correctly use electrical circuits, you need to familiarize yourself with the basic concepts and definitions that affect this area in advance.

Any diagram is made in the form of a graphic image or drawing, which, together with the equipment, displays all the connecting links of the electrical circuit. Exist different kinds electrical circuits, differing in their intended purpose. Their list includes primary and secondary circuits, signaling, protection, control systems and others. In addition, there are and are widely used fundamental and, full-line and deployed. Each of them has its own specific features.

Primary circuits include circuits through which the main technological voltages are supplied directly from sources to consumers or receivers of electricity. Primary circuits generate, convert, transmit and distribute electrical energy. They consist of a main circuit and circuits that provide their own needs. Main circuit circuits generate, convert and distribute the main flow of electricity. Auxiliary circuits ensure the operation of the main electrical equipment. Through them, the voltage is supplied to the electric motors of the installations, to the lighting system and to other areas.

Secondary are those circuits in which the applied voltage does not exceed 1 kilowatt. They provide the functions of automation, control, protection, dispatching service. Through the secondary circuits, control, measurement and metering of electricity is carried out. Knowing these properties will help you learn how to read electrical circuits.

Full line circuits are used in three-phase circuits. They display the electrical equipment connected to all three phases. Single-line diagrams show equipment located on only one middle phase. This difference must be indicated on the diagram.

Schematic diagrams do not indicate secondary elements that do not perform primary functions. Due to this, the image becomes simpler, allowing a better understanding of the principle of operation of all equipment. Wiring diagrams, on the contrary, are carried out in more detail, since they are used for the practical installation of all elements of the electrical network. These include single-line diagrams displayed directly on the building plan of the facility, as well as cable route diagrams along with transformer substations and distribution points plotted on a simplified master plan.

In the process of installation and commissioning, detailed schemes with secondary circuits became widespread. They are allocated additional functional subgroups of circuits associated with turning on and off, individual protection of a section, and others.

Designations in electrical diagrams

In every electrical circuit there are devices, elements and parts that together form a path for electric current. They are distinguished by the presence of electromagnetic processes associated with electromotive force, current and voltage, and described in physical laws.

In electrical circuits, all components can be divided into several groups:

1. The first group includes devices that generate electricity or power sources.
2. The second group of elements converts electricity into other forms of energy. They perform the function of receivers or consumers.
3. The components of the third group provide the transfer of electricity from one element to another, that is, from a power source to electrical receivers. This also includes transformers, stabilizers and other devices that provide the necessary quality and voltage level.

Each device, element or part corresponds to symbol used in graphic images electrical circuits called electrical circuits. In addition to the main symbols, they display power lines connecting all these elements. Sections of the circuit along which the same currents flow are called branches. The places of their connections are nodes, indicated on electrical diagrams in the form of dots. There are closed paths for the movement of current, covering several branches at once and called circuits of electrical circuits. The most simple circuit the electrical circuit is single-circuit, and complex chains consist of several circuits.

Most circuits consist of various electrical devices that differ in different modes of operation, depending on the value of current and voltage. In idle mode, there is no current in the circuit at all. Sometimes such situations arise when connections are broken. In the nominal mode, all elements operate with the current, voltage and power that are indicated in the device passport.

All components and symbols of the elements of the electrical circuit are displayed graphically. The figures show that each element or device has its own symbol. For example, electrical machines may be depicted in a simplified or expanded manner. Depending on this, conditional graphic schemes are also built. Single-line and multi-line images are used to show winding leads. The number of lines depends on the number of pins, which will be different for various types machines. In some cases, for the convenience of reading the diagrams, mixed images can be used, when the stator winding is shown in expanded form, and the rotor winding is shown in simplified form. Others are done in the same way.

They are also carried out in a simplified and expanded, single-line and multi-line methods. This determines the way the devices themselves are displayed, their outputs, winding connections and other constituent elements. For example, in current transformers, a thick line marked with dots is used to depict the primary winding. For the secondary winding, a circle can be used with a simplified method or two semicircles with an expanded image method.

Graphic images of other elements:

• Contacts. They are used in switching devices and contact connections, mainly in switches, contactors and relays. They are divided into closing, opening and switching, each of which has its own graphic pattern. If necessary, the image of contacts in a mirror-inverted form is allowed. The base of the moving part is marked with a special unshaded dot.
• . They can be single pole or multi pole. The base of the moving contact is marked with a dot. At circuit breakers the image indicates the type of release. Switches differ in the type of action, they can be push-button or track, with break and make contacts.
• Fuses, resistors, capacitors. Each of them corresponds to certain icons. Fuses are depicted as a rectangle with taps. For fixed resistors, the icon can be with or without taps. moving contact variable resistor indicated by an arrow. Capacitor drawings show fixed and variable capacitance. There are separate images for polar and non-polar electrolytic capacitors.
• Semiconductor devices. The simplest of these are diodes with a p-n junction and one-sided conduction. Therefore, they are depicted as a triangle and an electrical connection line crossing it. The triangle is the anode and the dash is the cathode. For other types of semiconductors, there are their own designations defined by the standard. The knowledge of these graphic drawings greatly facilitates the reading of electrical circuits for dummies.
• Sources of light. Available on almost all electrical circuits. Depending on the purpose, they are displayed as lighting and signaling lamps with the help of the corresponding icons. When depicting signal lamps, it is possible to shade a certain sector corresponding to low power and low luminous flux. In alarm systems, along with light bulbs, acoustic devices are used - electric sirens, electric bells, electric horns and other similar devices.

How to read electrical diagrams correctly

The circuit diagram is graphic image all elements, parts and components between which an electronic connection is made using current-carrying conductors. It is the basis for the development of any electronic devices and electrical circuits. Therefore, every novice electrician must first master the ability to read a variety of circuit diagrams.

It is the correct reading of electrical circuits for beginners that allows you to understand well how to connect all the parts in order to get the expected end result. That is, the device or circuit must fully perform its assigned functions. For correct reading circuit diagram it is necessary, first of all, to familiarize yourself with the symbols of all its components. Each detail is marked with its own conventional graphic designation - UGO. Typically, such conventional signs display the general design, characteristics and purpose of a particular element. The most striking examples are capacitors, resistors, speakers and other simple parts.

It is much more difficult to work with components represented by transistors, triacs, microcircuits, etc. The complex design of such elements also implies a more complex display of them on electrical circuits.

For example, each bipolar transistor has at least three terminals - base, collector and emitter. Therefore, their conventional representation requires special graphic symbols. This helps to distinguish between parts with individual basic properties and characteristics. Each symbol carries certain encrypted information. For example, bipolar transistors can have a completely different structure - p-p-p or p-p-p, so the images on the diagrams will also be noticeably different. It is recommended that before reading the circuit diagrams, carefully read all the elements.

Conditional images are very often supplemented with clarifying information. On closer examination, you can see Latin alphabetic characters next to each icon. Thus, this or that detail is indicated. This is important to know, especially when we are just learning to read electrical circuits. There are also numbers next to the letters. They indicate the corresponding numbering or specifications elements.

1.2 Basic ME connection diagrams

When connected corporate network access to global networks, it is necessary to restrict access to the protected network from global network and from the protected network to the global network, as well as to ensure the protection of the connected network from remote UA from the global network. At the same time, the organization is interested in hiding information about the structure of its network and its components from users of the global network. Working with remote users requires the establishment of strict access restrictions to information resources protected network.

Often there is a need to have several segments with different levels of security in the corporate network:

freely accessible segments (for example, an advertising WWW server);

segment with limited access(for example, for access to employees of the organization from remote sites);

closed segments (for example, the financial local subnet of the organization).

To connect the ME, various schemes can be used, which depend on the operating conditions of the protected network, as well as on the number of network interfaces and other characteristics used by the ME. Schemes are widely used:

Network protection using a shielding router;
unified protection local network;

unified protection of the local network;

· with protected closed and not protected open subnets;

· with separate protection of closed and open subnets.

Let's take a closer look at the scheme with a protected closed and unprotected open subnet. If there are public open servers in the local network, then it is advisable to take them out as an open subnet to the ME (Figure 1).

This method has a high security of the closed part of the local network, but provides a reduced security of open servers located up to the ME.

Some MEs allow you to host these servers on your own. However, this solution is not the best from the point of view of the security of the DOE itself and the loading of the computer. It is advisable to use the ME connection scheme with a protected closed subnet and an unprotected open subnet only if there are low security requirements for an open subnet.

If there are increased requirements for the security of open servers, then it is necessary to use a scheme with separate protection of closed and open subnets.

global international computer network Internet

The Internet is based on large channels bandwidth- backbones connecting large network nodes. There are two main ways to connect a user to the Internet: ? permanent connection via dedicated line...

Using SQL in application programming

Once on the site, the user can register or log in. If the user tries to subscribe to the newsletter without authorization, a modal window will pop up with an invitation to enter the site...

Study of the organization of a small business access network to the Internet

An automated workstation (AWP) can be connected to the global network in various ways: Connecting a second computer to the Internet via a router If the office has a stationary computer and a second stationary computer has been purchased ...

Typical Wiring Diagram quartz resonator from 3 to 20 MHz to the AT91SAM7SE microcontroller is shown in fig. 4. Fig. 4...

Combo USB audio device with stand-alone MP3 player and Bluetooth enabled

USB combo audio device with standalone MP3 player functionality and Bluetooth support

The power supply for the F2M03MLA must be chosen carefully and may affect the performance of the module or even damage it. The manufacturer recommends using the XC6209B332MR voltage regulator from Torex...

Basic network protection schemes based on firewalls

When connecting a corporate or local network to global networks, it is necessary to: · protect the corporate or local network from a remote NSD from the side of the global network; hiding information about the structure of the network and its components from users ...

Combination Circuit Design

A combinational circuit (CS) is a circuit of logical (switching) elements that implements a Boolean function or a set of Boolean functions. In the general case, the CS can be represented by the diagram shown in Fig. 1, where x1, x2,....xn are the inputs of the COP, f1, f2,....

Design of a microprocessor control system

Figure 2.10 shows the connection diagram of the speaker BA1 for sound signaling. Transistor VT1 current amplifies the output signal from the RC0 line of the port. Figure 2.10 - Emergency sensor connection diagram In Figure 2...

Development and implementation of a computing device in the program "Minecraft"

Logic elements(in Minecraft for some reason they are called gates or valves) are the basis of all mechanisms. The NOT (inverter) element returns the opposite signal to the one received. This is an implementation of the logical NOT. Rice. 4. Inverter...

Development of a controller for a trackball pointer

The complexity of powering an optocoupler lies in the fact that + 5V needs to be powered by a photodiode, which is supplied with + 2.5V. Therefore, we need to add two resistors (R4 and R5) to get a voltage divider, they had the voltage drop we needed. Rice...

Communication via telecommunication networks

satellite channel. Sufficiently high speed of work, mobility. Such a connection requires expensive equipment and complex settings, high channel rental costs, dependence on weather conditions...

Database management systems in the enterprise

The software department has Pentium IV class machines with processors Intel Pentium 2.6 and Intel Celeron 1.7 Such computers are used for complex calculations, writing programs, processing information. Peripherals consist of plotter, laser printer...

Multifunction device maintenance

Connecting the MFP to the network is shown in Figure 3 Figure 3 - Connecting the MFP to the network If the connection is made without a network, then the connection is made without a router. This is used...

Remote control computer with mobile device

Before starting the remote control, you need to make sure that there is access to the network (WiFi or GRPS, depending on personal preference). When you run the application, you will see the following screen (Figure 4.5): Hosted at http://www.allbest.ru/ Hosted at http://www.allbest...

1. Dual Homed

The firewall in this connection option performs the physical and logical separation of the two networks, making a decision on the possibility of establishing a connection between them.

1.1. Demilitarized Zone (DMZ)

In some cases, the firewall allows the use of multiple network adapters with different security policies installed. For this, a DMZ is used.

Typically, a DMZ hosts services that must be available to both clients of the external network and clients of the protected network. Since access to the DMZ services must be carried out from an open network, the DMZ defines less stringent requirements for network security, but sufficient to organize protection against threats. If the network uses user groups with a clear distinction between available services or different levels of confidentiality of processed information, then the firewall can control network flows not only to external networks, but also between internal network segments. Allocation of DMZ, as well as support for multiple network interfaces, allows you to centrally manage the protection of network resources with various accepted security policies.

Example: Let there be a corporate web server that publishes company data on the corporate network. This data is retrieved by the web server from an internal database server. Access to the database server is allowed only on the internal network. To ensure the operation of the interface of the web database management system, it is necessary to allow access from the web server to the database server. Then, when accessing the web servers, we can easily access the database server.

Dedicating a web server in the DMZ not only solves the problem of protection against external threats, but also minimizes the possibility of penetration into the local network.

1.2. Allow routing between network interfaces

In most cases, routing is allowed between network interfaces at the level operating system, while the dynamic and static filtering mechanisms are controlled by traffic. During the boot/reboot process of the operating system, there is a brief moment in which network stack with the routing service loaded is enabled, but the firewall with its filtering rules has not yet loaded.

When the firewall uses only application proxies, there is no need to route packets. In this case, application proxies mediate between the client and the server without OS side routing support. In this case, routing between network interfaces can be disabled.

1.4. Firewall in local computer network

A firewall can be used to segment a local area network in order to increase its level information security and protection of individual network segments. Segmentation in the local network is used then:

When there are functional groups in the local network that process information with different levels of access,

When it is necessary to provide controlled access to application and service services,

When it is necessary to control the exchange of information flows between different functional groups.

2. Screen shield

Unlike a multi-interface firewall that separates two or more networks, a firewall (bastion host) is only connected to the internal network and has one network interface. In this scheme, great care is taken to configure the routing tables so that all incoming traffic is sent to the firewall interface, and on the internal network, the IP address of the firewall is specified as the gateway.

1. Shield subnet

The shield subnet configuration adds an extra layer of security to the shield configuration by introducing a network segment to improve shield network isolation.

ME technologies

1. Network address translation (NAT).

When using NAT, the firewall acts as an intermediary between two IP nodes, organizing 2 data transmission channels. In this case, a firewall using NAT interacts with an external IP host on behalf of an internal one, but using its own IP address.

Types of LAN IP addressing:

1. 10.0.0.0 – 10.255.255.255
2. 172.16.0.0 – 172.31.255.255
3. 192.168.0.0 – 192.168.255.255

NAT provides a simple and reliable protection by establishing the so-called "unidirectional routing", when network packets are transmitted through the firewall only from the internal network. Network address translation is carried out in three modes:

Dynamic

Static

Combined.

A distinction is also made between source address translation and destination address translation. NAT is applied in the following cases:

1. Security policy requires hiding the internal address space of the network

2. Changing host addresses on the network is not possible

3. You need to connect a network with a large number of hosts, but with a limited number of static IP addresses

Dynamic Broadcast

In dynamic mode, called port translation, the firewall has one external address. All calls to the public network from the internal network client are made using this address. The firewall, when a client accesses it, allocates a unique transport protocol port for the external IP address to it. Number of ports: 65000

Example: The LAN uses an unrouted network with an address space of 10.0.0.0. The LAN client wishes to establish a connection to the web server 207.46.130.149.

The OS generates regular IP packets and sends them to the network. When packets pass through the firewall, the latter changes the source address to the address of the external interface, and the source transport port to the first free port from the pool of unused ports and recalculates checksum. For a web server, the client is a host with an IP address of 200.0.0.1, that is, the ME. The server responds to the client in the normal way.

Dynamic translation with dynamic IP address sampling

In dynamic mode with dynamic sampling, external IP addresses are allocated dynamically from a pool of external addresses. As with dynamic translation, a transport port is used for each connection. The difference is that when the entire port pool is exhausted, the next external IP address is allocated.

Static address translation

In static translation, the external interface of the firewall is assigned as many registered IP addresses as there are hosts on the internal network.

Example:

1. The public segment client accesses the web server at 200.0.0.21. 2. The doe finds the appropriate rule in its routing table and replaces the destination address with 10.0.0.21.

3. The server returns a response packet with source address 10.0.0.21.

4. When leaving the local network, the ME replaces its address with 200.0.0.21.

Static translation with dynamic IP address sampling

This type translation does not use transport ports, and each client is dynamically assigned an IP address from a pool of external addresses.

Wiper device

The car can be equipped with windshield wipers SL-191A or SL-191B, which have different fastening of the brush levers. For SL-191A, they are fastened with a spring plate, and for SL-191B, with a nut. The SL-191A wipers use the ME-241 electric motor, and the SL-191B ME241 or ME-241A. In 1970-1972 windshield wipers SL-191 were also used. They had an ME-241A electric motor and brush levers fastened with a spring plate.

On BA3-2103 vehicles, SL-193 wipers are used. They differ from the windshield wipers of the VAZ-2101 car in their installation dimensions, brush levers and the brushes themselves, which have less aerodynamic resistance. In addition, the SL-193 wiper is somewhat different in the configuration of the glass area to be cleaned. These wipers are equipped with ME-241 electric motors.

A switch in the washer pump has been added to the windshield wiper circuit on the BA3-2103 car windshield(see Fig. 336, b).

The wiper consists of an electric motor, a lever mechanism, brushes with levers and is installed under the hood in the air intake box (Fig. 331). The pressing force of the brushes to the glass is 400-500 gf, and the swing frequency of the brush levers is in the range of 50-70 double strokes per minute. The axes of the brush levers rotate in ceramic-metal bushings impregnated with oil and do not require lubrication during operation.

Electric motor ME-241

(Fig. 332) - direct current with excitation from permanent magnets. A worm gearbox is combined into one unit with an electric motor.

Rice. 330. Electrical circuit relay PC528 enable sound signals by car BA3-2103

Rice. 331. General view of the wiper motor installed on the car: .1 - electric motor; 2 - gearbox cover; 3 - plug

Rice. 333. Electric motor ME-241A: 1 - cover; 2 - panel; 3 - switch pusher; 4 - contact disk of the switch; 5 - cam; 6 - gear reducer; 7 - gearbox housing; 8 - axis; 9 - crank; 10 - armature shaft; 11 - thrust bearing; 12 - body; 13 - stator winding; 14 - stator pole; 15 - anchor; 16 - brush holder; 11 - felt ring; 18 - bushing; 19 - thrust washer; 20 - coupling screw

The electric motor has a stamped steel housing 16, inside which two permanent magnets 11 are fixed with spring holders, forming a stator together with the housing. In the grooves of the armature core, made of steel plates, a wave winding is laid, the conclusions of the sections of which are soldered to the collector copper plates.

The armature shaft 12 rotates in two ceramic-metal bushings 15. Felt rings 13 impregnated with oil are placed around the bushings. Therefore, during operation, the bearings of the armature shaft do not require lubrication. The axial force acting on the armature shaft from the worm gear is perceived by the textolite washer 14, against which the rear end of the shaft rests. The front end of the shaft is pressed by a thrust bearing 6 with a spring.

The body of the electric motor is closed by cover 4, which is also the crankcase of the gearbox. On the inside, a plastic brush holder 9 with two graphite brushes is riveted to the cover, and in the gearbox housing there is a plastic worm gear 3 with a cam 8. The gear is pressed onto the axle 5. The other end of the axle has a conical knurled surface, on which the crank is put on and fastened with a nut. The axle rotates in a ceramic-metal bushing pressed into the cover.

Steel and textolite washers are installed between the gear and the crankcase. Outside, the axle is sealed with a rubber ring, then a textolite washer and a steel elastic corrugated washer are located. Then the water deflector ring and the snap ring are installed. The reduction gear ratio is 51:1.

Rice. 334. The electrical circuit of the electric motor ME-241A: 1 - anchor; 2 - shunt coil of the stator winding; 3 - brake coil of the stator winding; 4 - serial coil of the stator winding; 5 - electric motor switch Color designation of wires: G - blue; GB - blue with white stripes; MS - blue with black stripes; 3 - green; K - red

The crankcase is closed with a plastic panel 2 and a cover 1. The panel contains contact posts, to which wires are soldered and a spring plate 7 is attached with switch contacts that stop the motor when the brushes are in the lower position. The contacts of the spring plate are pressed against the lower post (in the figure) connected to the power source. When the protrusion of the gear cam is against the plate, it wrings it out of the lower rack and presses it against the upper rack connected to the ground.

The electric motor ME-241A (Fig. 333) has an electromagnetic mixed excitation.

The body 12 of the electric motor is made of steel pipe. Inside it, two steel poles 14 with winding coils 13 of the stator are fixed with screws. One (series) coil 4 (Fig. 334) is connected in series with the armature winding, and the other (shunt) 2 is parallel to it. In addition, there is one more coil - brake 3, placed together with the serial coil on one pole. It is activated only when the motor is turned off, creates a magnetic flux directed against the flow of the series coil and thus ensures a quick stop of the armature.

The armature grooves are spiral, and the collector is located on the side of the back cover. The axial movement of the shaft 10 (see Fig. 333) of the armature is eliminated using a nylon thrust bearing 11 with a spring. The gear worm is two-way and the gear ratio is 34:1.

The crank 9 is riveted to the gear axle 8, and the torque from the gear to the axle is transmitted through the stamped steel cam 5.

One steel washer is installed between the gear and the crankcase, and one textolite, two steel and a corrugated steel washer are placed between the crankcase and the crank.

The electric motor switch consists of a pusher 3 with a contact disk 4 and two contacts riveted to the panel 2. The contact disk is pressed against the contacts by a spring and closes them. When cam 5 presses on the pusher, the contact disk moves away and opens the contacts.

The wiper relay (Fig. 335) is used to obtain intermittent wiper operation. It is located under the instrument panel on the left side.

The relay has an elastic plastic casing and a getinax base, to which a core 3 with a winding and an electromagnet yoke 4 is riveted. A plastic support with two pairs of fixed contacts is attached to the yoke on one side with a screw, and on the other side, an armature 2 swings on the yoke. The current-carrying armature plate closes the upper or lower pair of contacts. The spring pulls the armature away from the core, and therefore the top pair of contacts is normally closed, and the bottom one is normally open.

Rice. 335. Electrical diagram of the relay RS514 Designation of the color of the wires: G - blue; GB - blue with white stripes; Zh - yellow; K - red

An interrupter 1 is also fixed on the base, having a bimetallic plate with a winding of nichrome wire. A resistor 5 is installed under the base, designed to reduce sparking between the breaker contacts.