Communications Security Equipment with tools of protection for
communication project YH00
Definition
Communication line protection: various protective measures adopted
to protect communication lines and equipment from damage or
interference by external electromagnetic fields or other
environmental factors.
Chinese name: communication line protection
Mbth: protection of tele communication line
Nickname: none
Applied disciplines: information communication
Features: electromagnetic field, environmental factors,
communication lines, protective measures
Source of impact
The electromagnetic field that affects the communication line
mainly comes from the following aspects:
1. strong wires: such as the high-voltage transmission lines we
often see, electrical transport equipment such as the catenary of
electric trains and the power supply lines of high-speed railways,
etc.
2, lightning, magnetic storms, and sunspot movement of
electromagnetic storms and other natural electromagnetic field
source.
3. electromagnetic waves radiated by radio stations,
radiotelegraph, etc.
4, the city's cable broadcasting network.
5, the industrial electromagnetic interference of industrial and
mining enterprises
6. power carrier line.
7, nuclear fusion electromagnetic pulse.
8, computer, microwave oven and other household appliances leaked
electromagnetic waves.
Influence of strong wires
The power supply of the strong wire is divided into two different
systems:
1, strong wire in each phase of the wire current and potential
amplitude is equal and the phase of the symmetrical system, such as
three-phase alternating current.
2, strong electric wire using the earth ( or other track ) as a
conductor of asymmetric system.
We need to understand that asymmetric systems and faulty symmetric
systems have a great influence on communication lines. And the
normal operation of the symmetrical system, the influence of
communication line is relatively small.
The current in a strong wire is magnetically affected in a
communication line by the electromagnetic mutual inductance (
coupling inductance ) between the strong wire and the communication
line. And the voltage of the strong wire through the coupling
capacitance between the strong wire and the communication line,
will produce a movie in the communication line. These
electromagnetic effects can impair the transmission quality of
electrical signals. The principle of the mutual inductance
phenomenon is shown in fig. 1.
Fig. 1 principle of electromagnetic mutual inductance
For the asymmetrical system of the strong electric wire, the ground
current of the strong electric wire will produce different ground
potential in different places of the earth, and the ground current
will be affected on the communication equipment by the action of
the coupling resistance.
The influence of these strong wires, heavy damage to communication
equipment or endanger the life safety of operation and maintenance
personnel; Light is produced in the telephone circuit noise, in the
telegraph circuit distortion, reduce the quality of communication.
Effect of lightning
Lightning and thunder, the natural phenomena of communication lines
will also have a significant impact. The technician classified
lightning:
1. linear lightning
2. flake lightning
3. chain lightning
4, ball lightning.
Of the four lightning types mentioned above, linear lightning is
the most harmful to communication lines.
The technician also classified the mine:
1. direct lightning strike: lightning strike directly on
communication line equipment. Direct lightning often damages
communication line equipment, causing serious harm.
2. induced lightning: lightning that does not directly hit the
communication line equipment but induces voltage and current in the
communication line. Induction lightning sometimes damage overhead
bright line of poor quality or unclean every electron; In most
cases, external equipment will not be damaged, but will cause
interference in the communication equipment, affecting the quality
of communication.
stray current
The following describes the effect of stray current on
communication lines:
In people's production and life, current is everywhere. Such as
electrical railways, high-speed rail, trams, other remote power
supplies, and even ground wires for direct current transmission
lines. We refer to these existing electrical flows as stray
currents.
Stray currents into the ground often cause electrical erosion (
electrolytic erosion ) of the metal sheath of underground cables
and optical cables. Dc erosion is more serious than AC erosion.
Note the following concepts:
1 ) cathode area: the area where stray current flows from the earth
into the communication line equipment.
2 ) anode area: the area where stray current flows back to earth by
line equipment.
It is common for that anode region to be subject to electrolytic
corrosion. Due to the different geological conditions, sometimes
the cathode area will also appear electrolytic corrosion
phenomenon. At the same time, the external natural environment is
complex and changeable, there will also be chemical intergranular
corrosion, microbial corrosion, soil corrosion, etc., which will
affect the communication line. Underground cables and cables can
also be " attacked" by termites, wasps and mice.
Influence of external electromagnetic field
What effect does the external electromagnetic field have on the
communication line?
1, high altitude nuclear explosion will form a strong
electromagnetic pulse, it not only harm to the metal cable; Some
optical cables without metal components may also have an impact. It
will increase the temperature of the optical fiber, which will
affect the transmission loss characteristics of the optical fiber.
2. high voltage transmission line: the strong electric field
generated by high voltage transmission line is an electromagnetic
pollution. If there is no reasonable protection of communication
line, also affect the quality of communication transmission.
-Established In 1995,we are the leading manufacture of
telecommunication parts and equipment in China;
-In past years,100% products is exported to over 50 country in the
world,we enjoy high quality and best service and flexible
production schedule,meeting your demands;
-In 2018,we build new export department,we want to have good start
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