2.3.1 Lightning
An electrical discharge that occurs between clouds and the ground, consisting of one or more lightning strikes.
2.3.2 Downward lightning discharge
A lightning discharge initiated by a downward leader from the clouds to the ground.
A downward lightning discharge consists of an initial impulse, and subsequent impulses may occur after the initial impulse. One or more impulses may be followed by prolonged lightning strikes.
2.3.3 Upward lightning discharge (upward lightning discharge)
A lightning discharge initiated by an upward leader from a grounded structure to a cloud.
An upward lightning discharge consists of an initial prolonged stroke, with or without multiple superimposed impulses. One or more impulses may be followed by prolonged lightning strikes.
2.3.4 Lightning strike
A single electrical discharge to the ground or protected structure.
2.3.5 Short-term lightning strike (短行程)
A type of lightning discharge corresponding to impulse current
The decay time of this current is generally less than 2ms.
2.3.6 Long-term lightning strike
A type of lightning discharge corresponding to a sustained current
The duration of the persistent current (the time from the starting point when the size of the wave head becomes 10% of the peak value until the size of the wave head becomes 10% of the peak value) is generally longer than 2 ms and less than 1 s.
2.3.7 Multiple lightning strikes
In general, the time interval between strokes is about 50 ms, and the average lightning discharge consists of 3-4 strokes.
The time interval between strokes ranges from 10 to 250 ms, and multiple strokes consisting of dozens of strokes have also been reported.
2.3.8 Lightning strike point (罢工点)
Lightning discharge occurs on the ground or protruding objects (e.g. structures, LPS, tracks, trees, etc.)
A lightning discharge may occur at two or more points of lightning strike.
2.3.9 Average degree of impulse current wave head
Time interval ∆t = average rate of change of current during
This is the difference in current magnitude at the start and end points of the time interval, ∆i = divided by the time ∆t =.
2.3.10 Wave head time of impulse current
A virtual parameter defined as the time interval between reaching 10% and 90% of the peak value multiplied by 1.25.
2.3.11 Conventional origin of impulse current
The intersection of the time axis and a straight line drawn to pass through the 10% and 90% reference points of the peak value at the head of the brain current. The convention origin precedes the moment when it becomes 10% of the peak value. The convention origin precedes the moment when it becomes 10% of the peak value.
2.3.12 Breakdown time, which is 1/2 of the impulse current.
A virtual parameter defined as the time interval from the origin and end of the convention to the moment of reaching 1/2 of the peak value.
2.3.13 Lightning discharge duration
Time during which lightning current flows at the point of lightning strike
2.3.14 Duration of long-term lightning current TLONG（长行程电流持续时间）
The time that lasts from the moment the long-term lightning current reaches 10% of the peak value in the rising part to the moment it reaches 10% of the peak value in the falling part.
2.3.15 Lightning discharge charge QFLASH（闪存充电）
Time-integrated value of brain current during the entire brain discharge time
2.3.16 Impulse charge QSHORT（脉冲电荷）
The time-integrated value of the lightning current in a short-term lightning stroke
2.3.17 Long-term lightning charge QLONG（长冲程充电）
Flashover is the value obtained by integrating the lightning current with time in a long-term lightning stroke.
2.3.18 Specific energy (比能量)
It is the time-integrated value of the square of the lightning current during the entire lightning discharge duration, and refers to the energy dissipated by the lightning current at unit resistance.
2.3.19 Specific energy of impulse current
The value obtained by integrating the square of the lightning current with time during the short-term lightning stroke duration.
Remarks The specific energy of a long-term lightning stroke can be neglected.
2.3.20 Structures subject to protection
Structures requiring protection against the effects of lightning strikes according to this standard
NOTE The structure to be protected may be part of a larger structure.
2.3.21 Line
Power lines or communication lines connected to structures subject to protection
2.3.22 Communication line (电信线路)
Lines used for communication between devices that may be located on different structures, such as telephone lines and data lines.
2.3.23 Power lines
Lines that supply electrical energy to structures where electrical devices and electronic devices are located, such as low-voltage or high-voltage lines
2.3.24 Lightning strike of structure
Lightning strike acting on the protected structure
2.2.25 Lightning strike near the structure
A lightning strike near a protected structure sufficient to cause a dangerous overvoltage.
2.3.26 Electrical system
A system consisting of low-voltage power supply elements
Remarks In IEC, high voltage or higher voltages are generally viewed as supplier equipment.
2.3.27 Electronic system
Systems comprised of sensitive electronic devices such as communication equipment, computers, control and measurement systems, radio systems, and power electronics equipment.
2.3.28 Internal system
Electrical and electronic systems inside the structure
2.3.29 Physical damage
Damage to structure (or contents) due to mechanical, thermal, chemical, or explosive effects of lightning discharge
2.3.30 Livestock injury
Permanent injury, including death, to animals or people due to electric shock caused by contact voltage and step voltage generated by lightning discharge.
NOTE Although animals may be injured in other ways, the term 'injury to animals' in this standard is limited to the threat of electric shock (injury type D1).
2.3.31 Failure of electrical and electronic systems
Permanent damage to electrical and electronic systems caused by lightning electromagnetic impulse (LEMP)
2.3.32 Brain electromagnetic impulse (LEMP)
All electromagnetic effects caused by lightning currents through resistive, inductive and capacitive combinations that produce surges and radiated electromagnetic fields.
2.3.33 surge
Transient phenomenon caused by lightning electromagnetic impulse (LEMP) that appears as overvoltage and/or overcurrent
2.3.34 Lightning protection zone LPZ
Area where the brain electromagnetic environment is defined. The zone boundaries of the LPZ are not limited to physical boundaries (e.g. walls, floors, ceilings).
2.3.35 risk
The average annual value of losses that can be caused by lightning discharges in relation to the total value (people or equipment) of the structure to be protected.
2.3.36 Acceptable risk
Maximum allowable risk for the structure to be protected
2.3.37 Lightning protection level LPL (防雷等级)
A level determined by a set of lightning current parameters related to the probability that the maximum and minimum design values will not exceed naturally occurring lightning discharges.
Remarks Lightning protection level is used to design protection measures according to a series of lightning current parameters.
2.3.38 Protection measures
Measures applied to structures to be protected to reduce risks
2.3.39 Lightning protection LP
An overall system for protecting not only people but also structures, including internal systems and contents, from brain discharges, generally consisting of LPS and SPM.
2.3.40 Lightning protection system (LPS)
A complete system used to reduce physical damage caused by lightning strikes to structures.
Remarks The lightning protection system consists of an external lightning protection system and an internal lightning protection system.
2.3.41 External lightning protection system
A type of lightning protection system consisting of an air-termination system, a down-conductor system, and an earth electrode system.
2.3.42 Internal lightning protection system (internal lightning protection system)
Part of a lightning protection system consisting of lightning equipotential bonding and/or external LPS and electrical insulation.
2.3.43 Air-termination system
Part of an external lightning protection system using metal objects such as lightning rods, reticulated conductors, overhead branch wires, etc. for the purpose of capturing lightning strikes.
2.3.44 Down conductor system (low conductor system)
Part of an external lightning protection system for passing lightning current from the air-termination system to the ground electrode system.
2.3.45 Earth electrode system
Part of an external lightning protection system to discharge lightning current to the ground.
2.3.46 External conductive part
A metal object that is drawn in or out of a structure to be protected, such as a pipe, a metal element of a cable, or a metal duct, through which a portion of the lightning current can flow, and extends to the outside.
2.3.47 Lightning equipotential bonding EB (lightning equipotential bonding)
Direct conductive connection or surge protection device to reduce potential difference due to lightning current
2.3.48 Conventional grounding impedance
Although they generally do not occur simultaneously, the ratio of the peak values of the ground electrode voltage and the ground electrode current
2.3.49 LEMP protection measures SPM (LEMP protection measures)
Measures to protect internal systems from the effects of lightning electromagnetic impulses (LEMP)
2.3.50 Magnetic shielding
A grid-shaped or continuous shield made of metal in a closed circuit that surrounds the structure to be protected or part of it to reduce failure of electrical and electronic systems.
2.3.51 Surge protection device (SPD)
A device comprising at least one nonlinear element for limiting transient overvoltages and amperaging surge currents.
2.3.52 Coordinated SPD system (协调SPD系统)
SPDs are appropriately selected, combined, and installed to reduce failures in electrical and electronic systems.
2.3.53 Rated impulse withstand voltage
Indicates the dielectric strength of a device against overvoltage and the impulse withstand voltage specified by the manufacturer for the device or part thereof.
NOTE For the purpose of this standard, only the withstand voltage between the conductor and earth is considered.
2.3.54 Isolating interface（isolating接口）
A device that can reduce conduction surges on lines entering the lightning protection zone (LPZ).
The isolation interface includes a ground shield isolation transformer, a non-metallic optical cable, and an optical isolation element. The dielectric strength characteristics of these devices are suitable for intrinsic application as an insulating interface or application through SPD.