Lightning Protection

Lightning protection term

2016/03/04

Air-termination system

Lightning rods, lightning protection belts (wires), lightning protection nets, metal roofing and metal components used for lightning strikes, etc.

 

Down-conductor system

Metal conductor connecting the lightning receptor to the grounding device

 

Earth-termination system

The sum of the grounding body and the grounding wire

 

Earth electrode

Conductor for scatter in buried soil or concrete foundation

 

Earth conductor

The connecting conductor from the down-conductor disconnecting card or changing line to the grounding body; or the connecting conductor from the grounding terminal, equipotential bonding to the grounding device

 

Lightning protection system (LPS)

The sum of the lightning receptor, down conductor, grounding device, surge protector and other connecting conductors

 

Direct lightning flash

Lightning directly hits buildings, other objects, earth or lightning protection devices, producing electrical, thermal, and mechanical forces

 

Lightning induction

Electrostatic induction and electromagnetic induction generated on a nearby conductor when lightning is discharged, which may cause sparks between metal parts

 

Electrostatic induction

Due to the action of the thundercloud, the opposite conductor is induced on the nearby conductor. When the thundercloud is main discharge, the charge in the pilot channel is quickly neutralized, and the induced charge on the conductor is released, if not near the ground. High potential

 

Electromagnetic induction (Electromanetic induction)

Due to the rapid change of lightning current, a transient strong electromagnetic field is generated in the surrounding space, which induces a high electromotive force on the nearby conductor.

 

Lightning Surge on incoming Services

Due to the effect of lightning on overhead lines or metal pipes, lightning waves may invade the house along these lines, endangering personal safety or damaging equipment.

 

Information system

Many types of electronic devices in buildings, including computers, communication devices, control devices, etc.

 

Downward flash

Beginning with the downward lead generated by Thundercloud to the earth. A downward flash has at least one first short-term lightning strike, followed by multiple subsequent short-term lightning strikes and may contain one or more long-term lightning strikes

 

Upward flash

Beginning with an upward leader from the connected buildings to Thundercloud. An upward flash has at least one first long-term lightning strike with or without multiple super-short lightning strikes, followed by multiple short-term lightning strikes and possibly one or more long-term lightning strikes

 

Lightning stroke

One discharge in a flash

 

Short stroke

Lightning strike with a half-time T2 of pulse current shorter than 2ms

 

Long stroke

Lightning from a peak of 10% of the wave head to a peak of 10% from the peak to a peak of 2ms and less than 1s

 

Point of strike

The point at which lightning strikes contact the earth, buildings, or lightning protection devices

 

Lightning current

Current flowing into the lightning strike point

 

Specific energy

The integral of the square of the lightning current over time during a flash. It represents the energy produced by a lightning current on a unit of resistance.

 

Lightning electromagnetic impulse (LEMP)

It is a source of interference. This specification refers to the effects of lightning directly hitting lightning protection devices and buildings near buildings. The vast majority are interference through connecting conductors, such as lightning current or part of lightning current, potential rise of devices struck by lightning, and electromagnetic radiation interference.

 

Lightning protection zone (LPZ)

Those areas that need to specify and control the lightning strike electromagnetic environment

 

Equipotential bonding, bonding

Separating devices, conductive objects with equipotential bonding conductors or surge protectors to reduce the potential difference between the lightning currents

 

Equipotential bonding belt (Bonding bar)

a metal strip to which metal devices, foreign conductive materials, power lines, communication lines, and other cables are connected to be equipotentially connected to the lightning protection device

 

Equipotential bonding conductor

a conductor that interconnects portions of separate devices to equal potential between them

 

Equipotential bonding network

a network of equipotentially connected conductors from exposed conductive portions of a system

 

Common earthing system

All interconnected metal devices connected to a grounding device, including lightning protection devices

 

Earthing reference point (ERP)

The only connection point between a system's equipotential bonding network and the shared grounding system

 

Surge protector (surge protector, formerly known as overvoltage protector) (Surge protective device, SPD)

The purpose is to limit the transient overvoltage and the device that separates the surge current. It contains at least one nonlinear component

 

Maximum continuous operating voltage UC (Maximum continuous operating voltage)

The maximum square root voltage or DC voltage that may be continuously applied to the surge protector, equal to the rated voltage of the surge protector

 

Nominal discharge current

The peak current flowing through the SPD, 8/20μs current wave. Used for class II classification test of SPD, also used for pretreatment of SPD class I and class II classification tests

 

Impulse current Iimp(Impulse current)

Provisions include amplitude current Ipeak and charge Q

 

Maximum discharge current Imax for class II test

The peak current flowing through the SPD, 8/20μs current wave. Used for class II classification tests. Imax is greater than In

 

Level I classification test (Calss I tests)

Test with nominal discharge current In, 1.2/50 μs impulse voltage and maximum inrush current Iimp. The charge Q(As) passed by the maximum inrush current within 10ms is equal to one-half of the amplitude current Ipesk(kA), ie Q(As)=0.5Ipesk(kA)

 

Level II classification test (Calss I tests)

Test with nominal discharge current In, 1.2/50 μs impulse voltage and maximum inrush current Imax.

 

Combination wave

The generator generates a 1.2/50μs surge voltage applied to the open circuit and an 8/20μs surge current applied to the short circuit. The open circuit voltage is Uoc.

 

Level III classification test (Calss III tests)

Test with mixed wave (1.2/50μs, 8/20μs)

 

Voltage switching type SPD (Voltage switching type SPD)

When there is no surge, it is high impedance, and when there is a voltage surge, it mutates to low impedance. Discharge gaps, gas-filled discharge tubes, thyristors, and triacs are typically used as components of such SPDs. Sometimes this type of SPD is called "short-circuit switch type" or "robot type" SPD.

 

Pressure limiting type SPD

When there is no surge, it is high impedance. As the surge current and voltage increase, the impedance continues to decrease. Varistors and suppression diodes are commonly used to make components of such SPDs. Sometimes called SPD is a "clamped" SPD

 

Combined SPD (Combination type SPD)

It is a combination of a voltage switching type component and a voltage limiting type component, which can be displayed as a voltage switching type or a voltage limiting type or both, depending on the characteristics of the applied voltage.


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