RF communications equipment. The principle of operation and the purpose of HF communication channels of high-voltage power lines. The design and composition of the equipment

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The design of the power line, determined by its main purpose - the transmission of electrical energy over a distance, allows it to be used to transmit information. The high level of operation and high mechanical strength of the lines ensure the reliability of communication channels close to the reliability of channels via cable communication lines. At the same time, when implementing communication channels for information transmission over overhead lines, it is necessary to take into account the features of the lines that make it difficult to use them for communication purposes. Such a feature is, for example, the presence of substation equipment at the ends of the lines, which can be represented as a chain of reactive and active resistances that vary over a wide range and are connected in series. These resistances form a connection between the overhead lines through the buses of substations, which leads to an increase in the communication path. Therefore, to reduce the influence between the channels and attenuation, with the help of special barriers, they block the paths of high-frequency currents towards substations.
Branches from overhead lines also significantly increase attenuation. These and other features of the lines require the implementation of a number of measures to create conditions for the transmission of information.
The device of high-frequency channels along distribution networks of 6-10 kV is associated with significant difficulties due to the specifics of building networks of these voltages. On sections of 6-10 kV trunk lines between neighboring switching points, there are a large number of taps, the lines are sectioned off by disconnectors and switches, the primary switching circuits of networks often change, including automatically, due to the greater damage to the lines of these voltages, their reliability is lower than B71 35 kV and above. Signal transmission in distribution networks depends on many factors that affect signal attenuation: on the length and number of taps, line wire material, load, etc. The load can vary over a wide range. At the same time, turning off individual taps, as studies show, sometimes not only does not reduce attenuation, but, on the contrary, increases it due to a violation of the mutual compensation of attenuation between adjacent taps. Therefore, channels of even a small length have significant attenuation and are unstable. The operation of the channels is also negatively affected by damage to the insulators, poor-quality connection of wires and the unsatisfactory condition of the contacts of the switching equipment. These defects are sources of interference commensurate with the level of the transmitted signal, which can cause the channel to stop working and damage the equipment. The presence of sectioning devices on the lines leads to a complete cessation of the operation of the RF channel in the event of their disconnection and grounding of one of the line sections. The noted shortcomings significantly limit, although they do not exclude, the use of 6-10 kV lines for organizing HF channels. Nevertheless, it should be noted that HF ​​communication over distribution networks has not yet received wide distribution.
By purpose, HF communication channels over power lines are divided into four groups: dispatch communication channels, technological, special and linear operational communication channels.
Without dwelling in detail on the use and purpose of each group of channels, we note that for dispatching and technological channels of telephone communication, the voice frequency band of 300-3400 Hz is mainly used.<300-2300). Верхняя часть тонального спектра (2400-3400 Гц) не пользуется для передачи сигналов телеинформации. Современная комбинированная аппаратура позволяет организовать в этом спектре до четырех независимых узкополосных каналов телеииформации.
Line-operational communication channels serve to organize communication between the dispatcher and repair teams working on the route of an extended power transmission line or substations, when there is no constant communication with them. For these channels, simplified transportable and portable telephone equipment is used.
According to the degree of complexity, HF channels are divided into simple and complex. Channels consisting of only two sets of terminal RF equipment are called simple. Complex channels incorporate intermediate amplifiers or several sets of terminal equipment (at the same frequencies).

Equipment for high-frequency communication channels for overhead lines.

The connection of communication equipment to the wires of the power line is carried out using special devices of the so-called equipment for connecting and processing the line, consisting of a communication capacitor, a barrier and protection elements.

Rice. 21. Scheme of a high-frequency communication channel over overhead lines
On fig. 21 shows a diagram of the formation of a communication channel over an overhead line. Transmission of signals by high-frequency currents It is carried out by transmitters of the sealing equipment J, located at both ends of the overhead lines at substations A and B.
Here, as part of the sealing equipment 1, there are receivers that receive modulated RF currents and convert them. To ensure the transmission of signal energy by high-frequency currents through wires, it is enough to process one wire at each end of the line using a barrier 5, a coupling capacitor 4 and an attachment filter 3, which is connected to sealing equipment 1 using an RF cable 2. To ensure the safety of personnel working on the attachment filter when the RF channel is running, the grounding knife 6 serves.
Connection of high-frequency equipment according to the scheme of fig. 21 is called phase-to-earth. Such a scheme can be used to form single-channel and multi-channel information transmission systems. Other connection schemes are also used.
If it is necessary to connect equipment installed on the line route to the power line (mobile telephone equipment of repair teams, equipment of a remotely controlled VHF radio station, etc.), antenna connection devices are usually used. As an antenna, pieces of insulated wire of a certain length or sections of a lightning protection cable are used.
The high-frequency (linear) arrester has a high resistance for the operating frequency of the channel and serves to block the path of these currents, reducing their leakage towards the substation. In the absence of a barrier, the attenuation of the channel may increase, since the small input impedance of the substation shunts the RF channel. The barrier consists of a power coil (reactor), a setting element and a protection device. The power coil is the main element of the minelayer. It must withstand the maximum operating currents of the line and short-circuit currents. The power coil is made of copper or aluminum wires of the appropriate section, twisted into a spiral, wound on laths of wood-laminated plastic (delta-wood) or fiberglass. The ends of the rails are fixed on metal crosses. An adjustment element with protective arresters is attached to the upper crosspiece. The tuning element serves to obtain a relatively high barrier resistance at one or more frequencies or frequency bands.
The tuning element consists of capacitors, inductors and resistors and is connected in parallel
power coil. The power coil and the setting element of the barrier are exposed to atmospheric and switching overvoltages and short circuits. The role of overvoltage protection, as a rule, is performed by a valve-type arrester, consisting of a spark gap and a non-linear wilite resistor.
In electrical networks of 6-220 kV, barriers VZ-600-0.25 and KZ-500, as well as barriers with a steel core of types VChZS-100 and VChZS-100V, which differ from each other in rated current and inductance, stability and geometric parameters power coil, as well as the type of setting element and its protection.
The barriers cut into the phase wire of the power line between the line disconnector and the coupling capacitor. High-frequency barriers can be mounted suspended, on supporting structures, including coupling capacitors.
Coupling capacitors are used to connect HF equipment to an overhead line, while the leakage currents of industrial frequency are diverted through the coupling capacitor to the ground, bypassing the high-frequency equipment. Coupling capacitors are designed for phase voltage (in a network with grounded neutral) and for line voltage (in a network with isolated neutral). In our country, two types of coupling capacitors are produced: CMP (coupling, oil-filled, with an expander) and CMM (coupling, oil-filled, in a metal case). For different voltages, capacitors are made up of individual elements connected in series. Coupling capacitors can be installed on reinforced concrete or metal supports with a height of about 3 m. To isolate the lower element of the CMP type capacitor from the support body, special round-section porcelain supports are used.

The connection filter serves as a link between the coupling capacitor and the RF equipment, separating the high voltage line from the low current installation, which is the sealing equipment. The connection filter thus ensures the safety of personnel and protection of equipment from high voltage, since when the lower lining of the coupling capacitor is grounded, a path is formed for leakage currents of industrial frequency. With the help of the connection filter, the wave impedances of the line and the high-frequency cable are matched, as well as the reactance of the coupling capacitor is compensated in a given frequency band. Connection filters are made according to transformer and autotransformer circuits and together with coupling capacitors form band-pass filters.
The most widely used in the organization of HF communication channels along the power lines of the enterprise was the connection filter of the OFP-4 type (see Fig. 19). The filter is enclosed in a welded steel housing with a bushing for connecting the coupling capacitor and a cable funnel for entering the RF cable. An arrester is mounted on the housing wall, which has an elongated pin for connecting the ground bar and is designed to protect the connection filter elements from overvoltages. The filter is designed for connection of HF equipment in a phase-to-ground circuit, complete with coupling capacitors with a capacity of 1100 and 2200 pF. The filter is installed, as a rule, on the support of the coupling capacitor and is bolted to the support at a height of 1.6-1.8 m from the ground level.
As noted, all switching in the connection filter circuits is carried out with the grounding knife turned on, which serves to ground the lower lining of the coupling capacitor during personnel work. A single-pole disconnector for a voltage of 6-10 kV is used as a grounding knife. Operations with a grounding knife are carried out using an insulating rod. Some types of connection filters have a grounding knife mounted inside the housing. To ensure safety in this case, a free-standing earthing knife should be installed.
The high-frequency cable is used for the electrical connection of the connection filter (see Fig. 21) with the transceiver equipment. When connecting the equipment to the line according to the phase-to-ground scheme, coaxial cables are used. The most common is a high-frequency coaxial cable of the RK-75 brand, the inner conductor (solid or stranded) of which is separated from the outer braid by high-frequency dielectric insulation. The outer shield braid serves as the return conductor. The outer conductor is enclosed in a protective insulating sheath.
The high-frequency characteristics of the RK-75 cable, as well as conventional communication cables, are determined by the same parameters: wave resistance, kilometric attenuation and electromagnetic wave propagation speed.
Reliable operation of HF channels over overhead lines is ensured by high-quality and regular execution of scheduled preventive maintenance, which provides for a whole range of work on the equipment of HF communication channels over overhead lines. To perform preventive measurements, the channels are taken out of service. Preventive maintenance includes scheduled checks of equipment and channels, the frequency of which is determined by the condition of the equipment, the quality of operational maintenance, taking into account preventive maintenance, and is set at least once every 3 years. Unscheduled channel checks are performed when the RF path is changed, equipment is damaged, and the channel is unreliable due to violation of the regulated parameters.

MOSCOW, May 11 - RIA Novosti. Vladimir Bogomolov's book Moment of Truth about the Great Patriotic War often mentions "high-frequency notes" and high-frequency communication devices, through which the supreme commander-in-chief contacted the headquarters. The communication was secure, and it was impossible to eavesdrop on it without the use of special means. What was the type of connection?

"VCh-svyaz", "Kremlin", ATS-1 - a system of secure communication channels, which to this day ensures the stability and confidentiality of negotiations between heads of state, ministries, strategic enterprises. Protection methods have become much more complicated and improved, but the task has remained unchanged: to protect state-level conversations from prying ears.

During the Great Patriotic War, according to Marshal I.Kh. Baghramyan, "without high-frequency communications, not a single significant military operation was launched or carried out. High-frequency communications played an exceptional role as a means of command and control and contributed to the implementation of military operations." She was provided not only with headquarters, but also with command directly on the front lines, at sentinel posts, bridgeheads. Already at the end of the war, the contribution of government communications to the victory was most briefly described by the famous Marshal K.K. Rokossovsky: "The use of government communications during the war revolutionized command and control."

The basis of government communications, which appeared in the 1930s, was the principle of high-frequency (HF) telephony. It allows the transmission of a human voice "transferred" to higher frequencies, making it inaccessible for direct listening and making it possible to transmit several conversations over a single wire.
The first experiments with the introduction of high-frequency multichannel telephone communication were carried out since 1921 at the Moscow Electrosvyaz Plant under the direction of V.M. Lebedev. In 1923, the scientist P.V. Shmakov completed experiments on the simultaneous transmission of two telephone conversations at high frequencies and one at a low frequency over a cable line 10 km long.
A great contribution to the development of high-frequency telephone communications was made by the scientist, Professor Pavel Andreevich Azbukin. Under his leadership, in 1925, the first domestic high-frequency communication equipment was developed and manufactured at the Leningrad Research and Testing Station, which could be used on copper telephone wires.

To understand the principle of HF telephone communication, let us recall that an ordinary human voice produces air vibrations in the frequency band of 300-3200 Hz, and therefore, in order to transmit sound over a conventional telephone channel, a dedicated band is needed ranging from 0 to 4 kHz, where sound vibrations will be converted into electromagnetic. You can listen to a telephone conversation on a simple telephone line by simply connecting a telephone set, handset or speaker to the wire. But it is possible to put a higher frequency band through the wire, significantly exceeding the voice frequency - from 10 kHz and higher.

© RIA Novosti illustration. Alina Polyanina

© RIA Novosti illustration. Alina Polyanina

This will be the so-called carrier signal. And then the vibrations arising from the human voice can be "hidden" in a change in its characteristics - frequency, amplitude, phase. These changes in the carrier signal will transmit the sound of the human voice, forming an envelope signal. Attempts to eavesdrop on a conversation by connecting to the line with a simple telephone set will not work without a special device - only a high-frequency signal will be heard.
The first lines of government HF communications were stretched from Moscow to Kharkov and Leningrad in 1930, and soon the technology spread throughout the country. By the middle of 1941, the government HF communication network included 116 stations, 20 facilities, 40 broadcasting points and served about 600 subscribers. The work of engineers of that time also made it possible to launch the first automatic station in Moscow in 1930, which subsequently worked for 68 years.

During the Great Patriotic War, Moscow did not remain without a telephone connection for a single minute. Employees of the MGTS museum showed unique exhibits that ensured uninterrupted communication in difficult years.

At that time, scientists and engineers were solving problems to improve the protection of communication lines and at the same time were developing complex encryption equipment. The developed encryption systems were of a very high level and, according to the army leadership, largely ensured the success of military operations. Marshal G.K. Zhukov noted: "The good work of cryptographers helped win more than one battle." A similar opinion was shared by Marshal A.M. Vasilevsky: "Not a single report about the upcoming military-strategic operations of our army became the property of fascist intelligence."

The FOX series offers state-of-the-art solutions based on SDH/PDH primary network technologies, designed and tested for harsh environments. No other multiplexer solution provides such a wide range of specialized products - from teleprotection to Gigabit Ethernet using SDH technology and spectral division.

ABB pays special attention to the possibility of upgrading products to protect investments and offers effective tools for maintenance.

The complete communication solution of the FOX series consists of:

• FOX505: Compact access multiplexer with throughput up to STM-1.
• FOX515/FOX615: Up to STM-4 throughput multiplexer providing a wide range of user interfaces for data and voice systems. The implementation of teleprotection functions and other application-specific features ensure that all data access requirements in the enterprise are met.
• FOX515H: Complements the FOX range and is designed for high speed communications.
• FOX660: Multiservice platform for data communication systems.

All elements of the FOX515 series are managed by FOXMAN, ABB's unified network management system based on SNMP. Its open architecture allows integration with third-party control systems, both higher and lower levels. Graphical network display and point-and-click control make FOXMAN the ideal solution for managing TDM and Ethernet at the access and data layers.

Universal Digital RF Communication System ETL600 R4

The ETL600 is a state-of-the-art solution for providing RF communications over power lines for the transmission of voice, data and protection commands over high voltage lines. The versatile hardware and software architecture of the ETL600 makes it pointless and obsolete to choose between traditional analog and advanced digital RF equipment. Using the same hardware components, the user can select digital or analog operating mode on site with just a few mouse clicks. In addition to ease of use, application flexibility and unprecedented data transfer rates, the ETL600 system also guarantees unconditional compatibility with existing technology environments and integrates well into today's digital communications infrastructures.

User Benefits

• An economical solution to the issue of organizing communications, providing reliable control and protection of the power system.
• Cost reduction through a common stock of hardware and spare parts for analog and digital HF communication systems over power lines.
• Flexible architecture for easy integration into both traditional and modern equipment.
• Reliable transmission of protection signals
• Efficient use of limited frequency resources through flexible transmission bandwidth selection.
• Redundant solution for selected mission-critical communications that are typically implemented via broadband communications

Connection filter MCD80

The MCD80 modular devices are used to connect the leads of an RF communication device such as the ABB ETL600 through a capacitive voltage transformer to high voltage lines.

The MCD80 filter provides optimum impedance matching for RF output, frequency separation and safe isolation of 50/60 Hz mains frequency and transient surges. It is configurable for single- and multi-phase communication by high-pass filtering or bandwidth. MCD80 devices comply with the latest IEC and ANSI standards.

Main advantages of MCD80 filters:

• Designed to work with any type of RF communication equipment
• The entire range of filters: broadband, bandpass, crossover, phase-to-phase, phase-to-ground
• Maximum possible bandwidth selection (according to customer specification in 1kHz steps)
• Possibility of connection both to coupling capacitors and voltage transformers
• Wide range of connection capacitances 1500pF-20000pF
• Possibility of restructuring at the installation site when changing the connection capacitance within the operating range of capacitances (for example, when replacing capacitors with voltage transformers)
• Low insertion loss in the passband (less than 1dB)
• It is possible to connect in parallel to one PF up to 9 terminals with a power of 80 W according to the phase-to-ground scheme and up to 10 terminals according to the phase-to-phase scheme
• Built-in single-pole disconnector (earthing switch)

HF barriers for VL-DLTC

There are two types of DLTC surge suppressors available for the protection of HF surge suppressors.

Small and medium-sized HF arresters are equipped with standard ABB Polim-D surge arresters without arc arresters.

Large barriers are equipped with ABB MVT arresters which do not have an arc gap and are specially designed for use with ABB barriers. They use the same extremely non-linear metal oxide varistors (MO arresters) as the station arresters.

When designing the tuner, the internal leakage MO of the restrictor is taken into account. ABB's metal oxide surge arresters are specifically designed to operate in the strong electromagnetic fields that are often present in HF line arresters. In particular, they do not contain unnecessary metal parts in which the magnetic field can induce eddy currents and cause an unacceptable increase in temperature. Modification of metal oxide surge arresters for line arrest conditions was necessary, as ABB manufactures such devices for stations and is fully aware of the problems that arise in practice. Surge arresters used in barriers on power lines have a rated current of 10 kA.

Features and Benefits

Principal advantages of HF interceptors of HF communication lines of the DLTC type

Information from the site

High-frequency communication equipment with digital signal processing (ADC) was developed by RADIS Ltd, Zelenograd (Moscow) in accordance with the terms of reference approved by the CDU of the UES of Russia*. AVC was accepted and recommended for production by the interdepartmental commission of JSC FGC UES in July 2003, it has a certificate of the State Standard of Russia. The equipment has been manufactured by RADIS Ltd since 2004.
* At present JSC SO-CDU UES.

Purpose and opportunities

ATC is designed to organize 1, 2, 3 or 4 channels of telephone communication, telemechanical information and data transmission over 35-500 kV power lines between the control center of a district or an electrical network enterprise and substations or any objects necessary for dispatching and technological control in power systems .

In each channel, telephone communication can be organized with the possibility of transmitting telemechanical information in the overtone spectrum by built-in or external modems, or data transmission using a built-in or external user modem.

AVC modifications

Combined variant

terminal AVC-S

Execution

The ADC widely uses methods and means of digital signal processing, which makes it possible to ensure the accuracy, stability, manufacturability and high reliability of the equipment. The AM OBP modulator/demodulator, transmultiplexer, adaptive equalizers, built-in telemechanics modems and service modems of control signals included in the ATC are made using signal processors, FPGAs and microcontrollers, and telephone automation and a control unit are implemented on the basis of microcontrollers. An STF/CF519C modem from Analytik is used as a built-in modem for data transmission in the channel.

Specifications

Number of channels	4, 3, 2 or 1
Operating frequency range	36-1000 kHz
Nominal bandwidth of one direction of transmission (reception):
- for single-channel	4 kHz
- for two-channel	8 kHz
- for three-channel	12 kHz
	16 kHz
Minimum frequency separation between the edges of the nominal transmit and receive bands:
- for one- and two-channel	8 kHz (up to 500 kHz)
- for three-channel	12 kHz (up to 500 kHz)
- for four-channel equipment	16 kHz (up to 500 kHz)
- one-, two-, three- and four-channel equipment	16 kHz (in the range 500 to 1000 kHz)
Maximum transmitter peak power	40 W
Receiver sensitivity	-25 dBm
Receiving path selectivity	meets the requirements of IEC 495
Receiver AGC Adjustment Range	40 dB
Number of built-in remote control modems (speed 200, 600 baud) in each channel
- at 200 baud	2
- at 600 baud	1
Number of connected external telemechanics modems in each channel	No more than 2
Number of built-in data modems (speed up to 24.4 kbps)	Up to 4
Number of connected external modems for data transmission	Up to 4
Rated impedance for RF output
- unbalanced	75 ohm
- balanced	150 ohm
Operating temperature range	0…+45°С
Food	220 V, 50 Hz

Note: with a balanced output, the midpoint can be connected to ground directly or through a 75 ohm 10W resistor.

Short description

The AVC-LF terminal is installed at the control room, and the AVC-HF terminal is installed at the reference or nodal substation. Communication between them is carried out by two telephone pairs. Frequency bands occupied by each communication channel:

Overlapping attenuation between the AVC-LF and AVC-HF terminals is not more than 20 dB at the maximum channel frequency (characteristic impedance of the communication line is 150 Ohm).

The effective bandwidth of each channel in the ADC is 0.3-3.4 kHz, and it can be used:

Telemechanics signals are transmitted using built-in modems (two for 200 baud, average frequencies 2.72 and 3.22 kHz, or one for 600 baud, average frequency 3 kHz) or external user modems.
Data transfer is carried out using the built-in STF/CF519C modem (depending on the line parameters, the speed can reach 24.4 kbps) or an external user modem. This makes it possible to organize up to 4 channels of machine-to-machine exchange.
In the receiving path of the AVC-LF (AVC-S), semi-automatic correction of the frequency response of the residual attenuation of each channel is provided.
Each telephone channel of the ATC has the ability to turn on the compander.

Telephone automation cell	AVC-LF (AVC-S) contains built-in devices for automatic connection of subscribers (telephone automation), which allow connection of:
If the channel is used for data transmission, then the telephone automation cell is replaced by the built-in STF/CF519C modem cell.	STF/CF519C Modem Cell

AVC-LF and AVC-S have a control unit that, using a service modem of each channel (transmission rate 100 Baud, average frequency 3.6 kHz), transmits commands and continuously monitors the presence of communication between local and remote terminals. When communication is lost, an audible signal is produced and the contacts of the external alarm relay are closed. In the non-volatile memory of the unit, an event log is kept (turning on/off and readiness of the equipment, "disappearance" of the communication channel, etc.) for 512 entries.

The necessary AVC modes are set using a remote control panel or an external computer connected via the RS-232 interface to the control unit. The remote control allows you to remove the level diagram and the characteristics of the residual attenuation of the channel, perform the necessary correction of the frequency response and evaluate the level of characteristic distortions of the built-in telemechanics modems.

The operating frequency of the equipment can be reconfigured by the user within one of the subranges: 36-125, 125-500 and 500-1000 kHz. Tuning step - 1 kHz .

Schemes for organizing communication channels

In addition to the direct communication channel (“point-to-point”), more complex schemes for organizing communication channels (of the “star” type) are possible between the ATC half-sets. So, a two-channel dispatcher half-set allows you to organize communication with two single-channel half-sets installed at controlled points, and a four-channel one - with two two-channel or four single-channel half-sets.

Other similar communication channel configurations are also possible. With the help of an additional ADC-HF terminal, the equipment provides the organization of four-wire transmission without channel selection.

In addition, the following options may be provided:

	Using only the AVC-HF terminal, work is organized in conjunction with an external modem having a bandwidth of 4, 8, 12 or 16 kHz in the nominal frequency range from 0 to 80 kHz, which allows you to create digital high-frequency communication complexes. For example, on the basis of the AVC-HF terminal and M-ASP-PG-LEP modems from Zelaks, it is possible to organize communication with a data transfer rate of up to 80 kbps in a 12 kHz band and up to 24 kbps in a 4 kHz band.
	In the nominal band of 16 kHz, two channels are organized in the ATC, namely the 1st with a 4 kHz band for telephone communication and the 2nd with a 12 kHz band for data transmission by user equipment.
	Operation of up to four single-channel subscriber ATC semi-sets is organized at controlled points with a single-channel dispatcher ATC semi-set. With a telephone channel bandwidth of 0.3-2.4 kHz, the equipment will provide one duplex communication channel for the exchange of telemechanical information at a rate of 100 Baud between the control room and each semi-set at the controlled point. When using external modems with a speed of more than 100 baud, only cyclic or sporadic exchange of telemechanical information between the dispatcher and subscriber half-sets is possible.

Weight and size parameters of the equipment

Name	Depth, mm		Height, mm

Installation

The equipment can be mounted on a rack (up to several vertical rows), in a 19” rack or mounted on a wall. All cables for external connections are connected from the front. By a separate order, an intermediate terminal block for connecting cables is supplied.

Environmental conditions

AVC is designed for continuous round-the-clock operation in stationary conditions, in enclosed spaces without permanent attendants at temperatures from 0 to + 45 ° C and relative humidity up to 85%. The performance of the equipment is maintained at an ambient temperature of up to -25 ° C.

To transfer information between protections and automation at the ends of a high-voltage line, a channel is used that is created for high-frequency currents according to the “phase-to-ground” connection scheme.

As part of the path, one phase of the operating overhead line is switched on, which, through coupling capacitors at substations, is connected to the ground to create a closed circuit for high-frequency currents.

Most often, two remote phases “A” and “C” are used on the line for transmitting frequency commands No. 1 from the substation through one of them, and receiving at frequency No. 2 through the second.

The device and purpose of the HF communication channel. Transmitters and receivers of high-frequency signals are installed at each substation. In this case, the modern equipment of RF transceivers is based on the microprocessor base of ABB's ETL640 v.03.32 terminals.

To process signals at each frequency, a transceiver is manufactured. Therefore, for one substation, 2 sets of terminals are required, configured to simultaneously receive and transmit signals on different phases of overhead lines.

The connection of the RF transceiver to the overhead line is handled by special equipment that separates high voltage from low-current equipment and creates a highway for the transmission of RF signals. It is completed with:

High-voltage coupling capacitor (CC);
- connection filter (FP);
- high-frequency barrier (VZ);
- HF cable.

The purpose of the high-voltage coupling capacitor is to reliably isolate from the ground the power transported through overhead lines with an industrial frequency and to pass high-frequency currents through itself.

In the photograph of the line in question, 3 capacitors with a phase transition are installed in each phase. They are used to communicate with far-end equipment in order to:

1. Transfer of RZ and PA commands;
2. Reception of RZ and PA commands;
3. Works of the RF equipment of the communication service.

To separate the HF signal from the high-voltage equipment of the substation, an HF barrier is mounted in the phase wire of the high-voltage overhead line. which limits the amount of loss of RF signals through parallel circuits.

Industrial frequency currents pass well through it and high-frequency currents are not passed. The VZ consists of a reactor (power coil) that passes the operating current of the line, and tuning elements connected in parallel with the reactor.

To match the parameters of the input impedance of the HF cable and line, a connection filter is used, which is performed by an air transformer model with taps from the windings, allowing you to make the necessary adjustments. The RF cable connects the connection filter to the transceiver.

High frequency transceivers (ETL640), purpose. Transceivers of the ETL640 type (PRM/TX) are designed to transmit and receive RF signals in the form of commands generated by relay protection (RP) and emergency automatics (PA) to the opposite end of the overhead line.

Checking the health of the RF channel. The complex equipment of the RF transmission path is located at distances of hundreds of kilometers, requires control and maintenance of its integrity. ETL640 transceivers at the ends of the overhead line constantly exchange (transmit / receive) control frequency signals in normal operation.

When the signal decreases in magnitude or its frequency changes beyond the permissible limits, a malfunction alarm is triggered. After the restoration of operability, the transceiver automatically returns to normal operation.

Signal exchange. Signals are transmitted and received at dedicated frequencies, for example:

Complex on phase “A”: Tx: 470 + 4 kHz, Rx: 474 + 4 kHz;
- complex on phase “C”: Tx: 502 + 4 kHz, Rx: 506 + 4 kHz.

The ETL640 equipment is designed for continuous round-the-clock operation in heated operating rooms.

Receiving and transmitting commands. Terminals No. 1 and No. 2 of ETL640 complexes receive and transmit 16 commands each from RH and PA.

ETL640 Transceiver Commands. Typical transceiver commands of any ETL640 complex can look like:

1. Shutdown of 3 phases of the 330 kV overhead line from the far end of the overhead line without control with the prohibition of the TAPV and start-up from the breaker failure or ZNR of the complex No. ... REL-670;

2. Disconnection of 3 phases of the 330 kV overhead line from the far end of the overhead line with control by measuring instruments Z3 DZ and the 3rd stage NTZNP of the REL670 protection complex No. ... without TAPV prohibition and starting from the 3-phase disconnection factor of the REL protection complex No. ...;

3. Teleacceleration of remote sensing with action on one or 3-phase shutdown of 330 kV overhead lines from the far end of the overhead line, with control of the parameters of stage Z3 DZ of complex No. ... of protection REL670 with OAPV / TAPV and starting from stage Z3 DZ of complex No. ... of protection REL- 670;

4. Teleacceleration NTZNP with action on one or 3-phase shutdown of the 330 kV overhead line from the far end of the overhead line with control of the parameters of the Z3 stage NTZNP of the complex No. ... of protection REL670 with OAPV / TAPV and starting from the measuring body of the 3rd stage NTZNP of the complex No. ... of protection REL670 ;

5. Fixing the disconnection of the line from its side of the overhead line and the action in the AFOL logic circuit of the complex No. ... of protection of the RPA. Start from the output relay of the AFOL logic circuit of the complex No. ... of the RPA protection when the line is disconnected from its side;

6. Stage III OH, acting on the launch:
- 5th team AKAP prd 232 kHz VL No…;
- 2nd team AKPA prd 286 kHz VL No…;
- 4th team ANKA prd 342 kHz VL No.….

7. Fixing the inclusion of the line on its part and the action in the AFOL logic circuit of the complex No. ... of the protection of the RPA VL with starting from the output relay of the AFOL logic circuit of the complex No. ... of the protection of the RPA VL-330 when turned on from its side;

8. Start from the 1st stage of the SAPAH circuit ... with the start:
- 6th team ANKA prd 348 kHz VL No…;
- 4th team AKAP prd 122 kHz VL No. ....

9. 3rd stage of load disconnection with action ...

Each command is formed for specific conditions of the overhead line, taking into account its configuration in the electrical network and operating conditions. Output relays of RF equipment and switching devices are located in a separate cabinet.

Overhead line signaling circuits. Terminal signaling. On the front panel of the terminals there are 3 LEDs that reflect the status of the REL670 device itself and 15 LEDs that indicate protections, faults and the state of the operational switches.

The LEDs of the terminals REL670 (protection of the 1st and 2nd complexes) and REC670 (automation and breaker failure of the 1st and 2nd complexes B1 and B2) of the first six numbers are red. LEDs numbered 7 to 15 are yellow.

Status indication LEDs. There are 3 LED indicators “Ready”, “Start” and “Trip” inserted above the block of LCD terminals REC670 and REL670. To indicate different information, they glow in different colors. The green color of the indicator means:

The operation of devices - a steady glow;
- internal damage - flashing;
- lack of power supply of operational current - darkening of color.

The yellow color of the indicator means:

Start of the emergency registrar - a steady glow;;
- finding the terminal in test mode - accompanied by flashing.

The red color of the indicator indicates the issuance of an emergency shutdown command (steady glow).

REC670 terminal LED signaling table

Resetting and testing the alarm. Resetting the alarm, counters for receiving and transmitting HF commands and information on the DZ and NTZNP zones for the terminal is carried out by pressing the SB1 button (alarm reset) on the front side of the cabinet.

To test the LEDs of the REL670 (REC670) terminals, you need to press and hold the SB1 button for more than 5 seconds.

General panel light signaling. On the front side of the REC670 cabinets there are lamps:
- HLW - works of automatic reclosure, ZNF, ROV;
- HLR2 - malfunction of automation systems and B-1 or B-2 breaker.

On the front side of REL670 cabinets there are lamps:
- HLW - protection works;
- HLR1 – protection complex is withdrawn;
- HLR2 - malfunction of protection systems.

On the front side of ETL cabinets there are alarm lamps:
- HLW1 – malfunction of ETL of the 1st complex;
- HLW2 - malfunction of ETL of the 2nd complex.

Prospects for the development of equipment for overhead transmission lines. Time-tested air circuit breakers for high-voltage power lines are gradually being replaced by modern SF6 structures that do not require constant operation of powerful compressor stations to maintain air pressure in tanks and air lines.

Bulky analog RPA and PA devices for high-voltage equipment, which require close attention from service personnel, are being replaced by new microprocessor terminals.