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DBT68-2017: Integrated lightning protection of seismic stations
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Integrated lightning protection of seismic stations
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DB/T 68-2017
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Basic data | Standard ID | DB/T 68-2017 (DB/T68-2017) | | Description (Translated English) | Integrated lightning protection of seismic stations | | Sector / Industry | Chinese Industry Standard (Recommended) | | Classification of Chinese Standard | P15 | | Word Count Estimation | 31,363 | | Date of Issue | 2017-09-26 | | Date of Implementation | 2018-01-01 | | Regulation (derived from) | China Seismological Bureau Website (2017.09.26); Industry Standard Filing Notice 2017 No.10 (Total No.214) | | Issuing agency(ies) | China Earthquake Administration | DBT68-2017: Integrated lightning protection of seismic stations---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Integrated lightning protection of seismic stations
ICS 91.120.25
P 15
Record number. 599910-2017
DB
People's Republic of China Earthquake Industry Standard
DB/T 68-2017
Comprehensive lightning protection for seismic stations
2017-09-26 released
Implementation of.2018-01-01
Issued by China Earthquake Administration
1 scope
This standard specifies the direct lightning protection, power distribution system protection, signal line protection and shielding measures in the integrated lightning protection of seismic stations.
And the basic requirements and methods of wiring protection, grounding and equipotential connection, lightning warning, and maintenance and management of lightning protection devices.
This standard applies to the comprehensive lightning protection design and maintenance management of seismic stations.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this
file. For undated references, the latest version (including all amendments) applies to this document.
GB 50052-2009 Code for Design of Power Supply and Distribution System
GB 50054-2011 Low Voltage Power Distribution Design Code
GB 50057-2010 Code for lightning protection design of buildings
GB 50343-2012 Technical Specification for Lightning Protection of Building Electronic Information System
GB 50689-2011 Communication Bureau (Station) Lightning Protection and Grounding Engineering Design Code
GB 18802.1-2011 Low Voltage Surge Protector (SPD) Part 1.Performance Requirements for Surge Protector for Low Voltage Distribution System
And test method
GB 18802.21-2016 Low Voltage Surge Protector Part 21.Surge Protector (SPD) for Telecommunications and Signal Networks ---
Performance requirements and test methods
3 Terms, definitions and abbreviations
3.1 Terms and definitions
The following terms and definitions apply to this document.
3.1.1
Seismic Observation System seismic observation system
A collection of software and hardware used for observation and measurement of geophysics, geochemistry, crustal deformation and other related phenomena related to seismic activity.
3.1.2
Integrated lightning protection integration lighting proction
A collection of various external and internal lightning protection measures, methods, and device applications.
3.1.3
Lightning protection device lighting process system
A device used for direct lightning protection and electromagnetic effects caused by lightning current.
DB/T 68-2017
3.1.4
Thunderstorm day
A day when thunder can be heard more than once in a day is called a thunderstorm day.
Note. Rewrite GB 50689-2011 and define 2.0.2.
3.1.5
Minefield high kerrainic zones
Areas where the average annual thunderstorm days are within 41 to 90 days.
Note. Rewrite GB 50689-2011, and define 2.0.5.
3.1.6
Strong minefield strong keraunic zones
Areas where the average annual thunderstorm days exceed 90 days.
Note. Rewrite GB 50689-2011 and define 2.0.6.
3.1.7
Air-termination
Metal objects that receive direct lightning discharge.
3.1.8
Downline
A conductor used to conduct lightning current from the air-termination device to the grounding device.
[GB 50057-2010, definition 2.0.9]
3.1.9
Earthing body earth electrode
Buried in the soil or concrete foundation as a conductor for dissipating current.
[GB 50057-2010, definition 2.0.11]
3.1.10
Ground wire earth wire
A conductor that does not carry current under normal conditions for connecting the ground terminal of the instrument and the grounding body or the neutral wire.
3.1.11
The combination of the grounding body and grounding wire that conducts lightning current and disperses it into the earth.
Note. Rewrite GB 50057-2010 and define 2.0.10.
3.1.12
Earthing earthing
The ground terminal of the equipment is connected to the grounding body or the neutral wire.
DB/T 68-2017
3.1.13
Common grounding system common earthing system
Connect the grounding device of the lightning protection system, the metal structure of the building, the low-voltage distribution protection line (PE), the equipotential connection terminal board or the connection belt,
The equipment protective ground, shield grounding, anti-static grounding, and functional grounding are connected together to form a common grounding system.
[GB 50343-2012, definition 2.0.6]
3.1.14
Earth net earth grid
A group of grounding bodies composed of interconnected bare conductors buried in the ground.
3.1.15
Earth bar earth bar
Rectangular or strip copper bars for receiving various grounding wires in the observation room.
3.1.16
8/20 μs impulse current 8/20 μs current impulse
An impulse current with an apparent wavefront time of 8 μs and a half-peak time of 20 μs.
[GB 50343-2012, definition 2.0.28]
3.1.17
Surge protector surge process device. SPD
A device used to limit transient overvoltage and split surge current.
Note. The surge protector contains at least one non-linear element.
3.1.18
Power lightning protection device power supple lighting proctiion dvice
A surge protector that prevents lightning and other overvoltages from invading the power system.
3.1.19
Signal lightning protection device signal lighting proction divece
A special surge protector to prevent lightning and other overvoltages from invading the signal equipment of the seismic observation system.
3.1.20
Residual voltag
When the discharge current flows through the surge protector, the peak voltage between its terminals.
[GB 50343-2012, definition 2.0.23]
3.1.21
Electromagnetic shielding electromagnetic shielding
Use conductive materials to reduce the penetration of alternating electromagnetic fields to designated areas.
[GB 50343-2012, definition 2.0.15]
DB/T 68-2017
3.1.22
Equipotential bonding equipotential bonding
Metal parts, foreign conductive objects, power lines, communication lines, and others separated by connecting conductors directly or through surge protectors
Cables are connected to reduce the potential difference generated by lightning current between them.
[GB 50343-2012, definition 2.0.12]
3.1.23
Cabling
A system composed of various cables, jumpers, plug-in cords and connecting devices connected to instruments and equipment.
3.1.24
Line ear line ear
Connect the terminals at the ends of the wires.
3.1.25
Earthing resistance earthing resistance
The resistance between the grounding body and the remote ground with zero potential.
Note. The resistance calculated by the current flowing into the ground from the grounding body is equal to the ratio of the voltage of the grounding body relative to the remote earth to the current flowing into the ground.
3.1.26
Lightning warning sign warning
Real-time detection of the electric field intensity in the air at different distances near the seismic station, and send out a lightning defense alarm signal.
3.2 Abbreviations
The following abbreviations apply to this document.
DDN. Digital Data Transmission Network (Digital Data Network).
GNSS. Global Navigation Satellite System (Global Navigation Satellite System).
PE. Protective conductor (Protecting Earthing).
PPR. Type III polypropylene (Polypropylene random).
PVC. Polyvinyl chloride (Polyvinyl Chloride).
PSTN. Public Switched Telephone Network (Public Switched Telephone Network).
TN-S. TN-S system (TN-S system).
TT. TT system (TT system).
UPS. Uninterruptible power supply (Uninterruptible Power Supply).
4 Basic requirements
4.1 When constructing and designing seismic stations, the local geology, geography, climate, environment and other conditions and the laws of lightning activity should be carefully investigated
Combining with the station layout, comprehensively integrate lightning protection in areas such as regional lightning protection, power supply line lightning protection, communication transmission line lightning protection, and sensor lead lightning protection.
Co-planning.
4.2 The lightning protection of the seismic observation system shall adopt lightning protection, shunting, shielding, isolation, equipotential connection, reasonable wiring, voltage limitation and common connection.
Comprehensive protection by measures such as land and ground.
DB/T 68-2017
4.3 The lightning protection design of the observation room of the seismic station shall meet the requirements of the second type of lightning protection structure in GB 50057-2010.
4.4 Seismic stations located in special geographical locations such as areas with heavy mines, strong mines, metal deposit areas, low-lying lakes and marshes, towering and protruding ridges, etc.
The ability to prevent lightning damage should be improved.
4.5 For the observation room of magnetic measuring instruments, the lightning protection device and other metal materials shall be made of copper.
5 Protection against direct lightning strikes
5.1 In a mine area with frequent direct lightning strikes, strong mine areas or seismic stations with direct lightning damage records, refer to GB for protection against direct lightning strikes
50057-2010.
5.2 The independent air-termination rod is used as the air-termination device, and the design diagram of its direct lightning protection design is shown in Figure 1.The selection of protection devices should meet the following requirements.
a) The distance between the pillars of the independent air-termination pole is more than 3 m from the protected building.
b) The distance between the ground grid of the independent air-termination pole and the ground grid of the seismic observation system shall not be less than 5 m.
5.3 For the observation room with reinforced concrete construction, the design diagram of its direct lightning protection design is shown in Figure 2.The selection of protection devices shall meet the following requirements.
a) Use the steel bars of the roof, column, and foundation of the building as down conductors, the number of which is not less than two, and the spacing along the circumference is not large
At 12 m.
b) The ground grid of the seismic observation system is laid around the building into a ring grounding device.
Figure 1 Schematic diagram of design of independent lightning rod for direct lightning protection
Figure 2 Schematic diagram of lightning protection design for reinforced concrete buildings
6 Protection of power distribution system
6.1 Requirements for power distribution system
6.1.1 The power distribution system of seismic stations shall follow the provisions of Appendix A.
6.1.2 Low-voltage AC power distribution, with armored cables buried in the ground and then introduced into the seismic station. Among them, the selection of armored cables should meet the following
Claim.
a) The cross-sectional area of the armored cable core wire is not less than 10 mm2.
b) The shortest length of the armored cable buried in the ground is greater than 15 m.
6.1.3 The power distribution system of seismic stations should be located at the main power distribution point, distribution point, stabilized power supply or uninterruptible power supply (UPS) front end, and seismic observation
The front end of the instrument is designed for lightning protection in grades. See Appendix B for its design diagram.
6.2 Multi-level protection design
6.2.1 Manned seismic stations shall be designed in accordance with the following requirements.
a) The general power distribution department is designed to protect the first-level AC power supply with lightning protection, and install a power supply lightning protection device with a discharge current of not less than 80 kA (8/20 μs).
b) The second-level AC power supply lightning protection is designed at the distribution office, and a power supply lightning protection device with a discharge current of not less than 40 kA (8/20 μs) is installed.
c) The third-level AC power supply lightning protection is designed at the input of the stabilized power supply or UPS power distribution, and the installation discharge current is not less than 20 kA (8/20 μs)
Power lightning protection socket.
d) The fourth-level AC power supply lightning protection is designed at the power input of the seismic observation instrument, and the installation discharge current is not less than 10 kA (8/20 μs)
Power lightning protection socket.
e) The installation positions of the first and second power lightning arresters are not less than 5 m apart.
6.2.2 Unattended seismic stations are designed in accordance with the requirements of no less than three levels of lightning protection.
a) The first-level AC power supply lightning protection is designed at the power distribution office of the observation room, and a power supply protection with a discharge current of not less than 80 kA (8/20 μs) is installed.
Mine weapon.
b) The second-level AC power supply lightning protection is designed at the input of the stabilized power supply or UPS power distribution, and the installation discharge current is not less than 20 kA (8/20 μs)
Power lightning protection socket.
c) The third-level AC power supply lightning protection is designed at the power input of the seismic observation equipment and the installation discharge current is not less than 10 kA (8/20
μs) lightning protection socket.
6.3 Other requirements for power distribution
6.3.1 The power distribution office of multiple buildings in the seismic station should be equipped with a first-level AC power supply lightning protection, and the installation discharge current should not be less than 80 kA (8/20 μs)
The power supply lightning protection device, the power supply lightning protection device should be switch type or switch, voltage-limiting hybrid type lightning protection device.
6.3.2 When the DC power supply is used alone, it should be installed with a suitable DC power supply lightning protection device according to its working voltage requirements.
6.3.3 The technical performance index of the power supply lightning arrester shall meet the requirements of GB 18802.1-2011.
6.3.4 The power surge protector shall have clear status indication, and its residual voltage shall meet the following requirements.
a) The residual pressure of the first stage is not higher than 2,000 V.
b) The residual pressure of the second stage is not higher than 1,500 V.
c) The residual voltage of the third and fourth levels shall not be higher than 1.5 times to 2.2 times of the rated working voltage of the equipment.
6.3.5 The connecting wire of the power lightning arrester should be short and straight, its length should not exceed 0.5 m, and the cross-sectional area should not be less than 10 mm2.
For the parameter installation process, the ground wire should be connected to the ground bar nearby.
6.3.6 The power lightning protection device at the entrance of the cave is grounded nearby, and the power lightning protection sockets of each room in the cave do not need to be grounded separately, but directly plug into the nearby
Use the protective wire PE of the AC power cord as the ground wire on the AC power socket.
6.3.7 Before a thunderstorm, the seismic station should manually or automatically turn off the AC power supply of the equipment.
DB/T 68-2017
7 Protection of signal lines
7.1 Protection requirements for signal lines
7.1.1 The protection of signal lines is for seismic observation instruments that are connected to external electrical appliances. seismic equipment, deformation equipment, electromagnetic equipment,
For fluid equipment, etc., signal lightning protection devices are added to the signal lines of these equipment. The schematic diagram of the signal line protection design of seismic stations is shown in Figure 3.
Figure 3 Schematic diagram of signal line protection design of seismic station
7.1.2 Seismic stations located in special geographical locations such as mine-rich areas, strong mine areas, metal deposit areas, low-lying lakes and marshes, towering and protruding ridges, etc.
Station, signal lightning protection devices should be installed on both sides of the signal line.
DB/T 68-2017
7.1.3 When the main unit of the seismic observation instrument and the sensor are in different buildings, the signal input terminal of the main unit of the seismic observation instrument should be installed
Signal lightning protection device.
7.1.4 When the main engine of the seismic observation instrument is inside the building and the sensor is outside the building.
a) The connection line between the outdoor sensor and the mainframe of the seismic observation instrument when entering the observation room should be installed at the input of the mainframe of the seismic observation instrument.
No. lightning protection device.
b) There is a separate signal amplifier in the sensor, and a signal lightning protection device should be installed at the signal input end of the signal amplifier.
7.1.5 When the seismic observation instrument and the data collector or the data collector and the communication equipment are not in the same building, the seismic observation instrument
Signal lightning protection devices should be installed on both sides of the signal line to the data collector and the signal line from the data collector to the communication equipment.
7.1.6 Seismic observation instrument host and sensor, seismic observation instrument and data collector, data collector and communication equipment are in the same house
When in a building, the application conditions of the signal lightning arrester for different building structures and signal line lengths should meet the requirements of Table 1.
7.1.7 Signal lightning protection devices should be installed in the following situations.
a) Both ends of the overhead connecting line of the seismic observation instrument.
b) The GNSS cable is at the input end of the instrument.
c) DDN or PSTN connection cable.
d) The antenna for wireless communication is outdoors, on the feeder side.
e) Seismic observation instrument connecting line not more than 10m from the entrance of the cave.
f) Seismic observation instruments with a distance of more than 10 m from the mouth of the cave have a signal input terminal with a signal amplifier.
g) The outdoor connecting line of the downhole seismic observation instrument is longer than 30 m, on both sides of the connecting line.
h) The analog input terminal of the sensor signal amplifier that does not have an overcurrent capability of 1 kA (8/20 μs) or more.
7.1.8 It is not necessary to install signal lightning protection devices in the following situations.
a) The antenna for wireless communication is indoors.
b) The connecting line of seismic observation instruments more than 10 m from the mouth of the cave.
7.2 Requirements for signal lightning protection device
7.2.1 The lightning protection performance should meet the requirements of GB/T 18802.21-2016.
7.2.2 The technical indicators shall meet the following requirements.
a) The series DC resistance is less than 0.5 Ω.
b) The discharge current is not less than 10 kA (8/20 μs).
c) The total harmonic distortion is less than 3%.
d) The maximum output error is less than 1%.
e) At zero input, the output noise (voltage or current, the same below) is not higher than the background noise of the seismic observation instrument.
f) Inter-channel interference, not higher than the background noise of seismic observation instruments.
g) The residual voltage is lower than the overvoltage withstand capability of the signal input and output ports or communication ports of the seismic observation instrument.
1) When the seismic observation instrument port has a clear withstand voltage index, its residual pressure is lower than 80% of the withstand voltage index.
2) When there is no clear withstand voltage index for the seismic observation instrument port, the residual voltage is lower than 2.4 times of the maximum range or maximum output voltage.
7.2.3 The protection capability shall meet the following requirements.
a) Horizontal protection between lines.
b) Vertical protection between line and ground.
c) Seamless connection between signal lightning protection device interface and seismic observation instrument interface.
d) Protection of the connecting line between the mainframe of the seismic observation instrument and its sensor.
7.3 Other requirements
7.3.1 The ground wire of the signal lightning protection device should be connected to the ground bar nearby. The cross-sectional area of the ground wire should not be less than 6 mm2, and the wire lug should be used for connection.
7.3.2 When installing the signal lightning protection device, the original connecting wire of the seismic observation instrument should not be cut off.
7.3.3 For the outdoor part of the downhole seismic observation instrument, its connection line shall be inserted into the galvanized steel pipe and buried in the ground.
7.3.4 If the measurement interval of the seismic observation instrument is relatively long and the connection line is overhead, the external line should be disconnected before the thunderstorm.
8.Shielding measures and wiring protection
8.1 Shielding measures
8.1.1 Seismic stations adopt measures such as building shielding, observation room shielding, equipment shielding, cable shielding, etc., refer to GB 50343
-2012.
8.1.2 The metal shell of the observation room's instruments and equipment should be reliably connected to the indoor grounding bar, and the cross-sectional area of the connecting wire should not be less than 6 mm2.
Use wire ear connections.
8.1.3 The measuring line and transmission line of the equipment should be shielded cables.
8.1.4 Both ends of the shielding layer of the shielded cable should be grounded. When single-ended grounding is required, two-layer shielding or laying through steel pipes should be used.
Both ends of the shield or steel pipe should be grounded.
8.1.5 Various cables entering and leaving the observation room should be buried in metal pipes.
8.1.6 The strong wires (power cables, etc.) in the observation room should be laid separately from the weak wires (signal wires and communication wires, etc.), and they should be embedded with gold wires.
It belongs to the trunking, and the metal trunking should be grounded.
8.1.7 Instruments and equipment should be centrally placed in standard metal cabinets. The cabinets should be placed in the center of the room, away from external walls and building columns.
It should not be less than 1 m.
8.1.8 An anti-static floor should be installed in the observation room with many instruments and equipment and concentrated.
8.1.9 The instrument and equipment observation room is in a multi-story high-rise building, and the instrument and equipment observation room should be located on the lower floor of the high-rise building.
8.2 Wiring protection
8.2.1 The wiring design should follow the principles of safety, reliability, application and economy, and be easy to install, operate, and maintain.
8.2.2 When laying cables, avoid damages such as mechanical, vibration, chemical, underground current, water corrosion, thermal influence, bee, ant, and rodent damage.
8.2.3 The communication lines between observation rooms laid outdoors shall be optical cables or optical partitions.
8.2.4 For communication lines with a length of more than 10 m in the observation room, optical cables or optical partitions should be used.
8.2.5 In the following cases, metal pipes or polyvinyl chloride pipes (PVC) or type three polypropylene pipes (PPR) should be embedded in the ground (wall) or embedded
The appropriate wiring duct laying.
a) Distribution lines from the distribution box to the sockets.
b) Except for the connection lines of the instruments with special requirements to be laid overhead, the connection lines of the other instruments outdoors.
c) Optical cables laid outdoors.
d) The connecting line in the cave.
8.2.6 When laying connecting wires with a length of more than 1 m along the outer wall of the building, protective measures such as strong wind and corrosion protection should be taken.
8.2.7 The signal lines of the seismic observation system should be short, straight and neat, and should meet the following requirements.
a) For cables laid in the ground, the buried depth is not less than 0.7 m.
b) In alpine areas, cables are buried below frozen soil.
c) The signal line is laid separately from the power distribution line, and the parallel distance outdoors is not less than 1 m, and the parallel distance indoors is not less than 0.5 m.
d) The indoor communication line is not less than 1 m away from the outer wall.
e) The parallel distance bet...
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