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Low voltage surge protection devices

Technical terminology in IEC61643 standards-1

2.1 Technical Term

2.1.1. Lightning electromagnetic impulse (LEMP)

It is a source of interference. Refers to the effect caused by lightning directly hitting the lightning protection device of a building or near the building. The vast majority are interferences through connecting conductors, such as lightning current or part of lightning current, the rise of the potential of the device struck by lightning, and electromagnetic interference.

Note: The lightning electromagnetic pulse is a kind of strong interference, which may cause failure or even damage to the electrical and electronic systems in the building. The electromagnetic interference is mainly the magnetic field effect and the induced voltage and current in the loop.

2.1.2. lightning surge on incoming services

Due to the effect of lightning on overhead lines or metal pipelines, lightning waves can invade the house along these pipelines, endangering personal safety or damage equipment.

2.1.3. Back-stroke

The potential rise caused by the lightning current flowing through the surge protector against lightning causes the discharge or breakdown of other metal parts, equipment, and leads.

2.1.4. switching overvoltage

Transient over-voltage caused by internal operation, faults, etc. of the power grid.

2.1.5. information system

A collective term for many types of electronic devices in a building, including computers, communication equipment, and control devices.

2.1.6. electronic system

A collective term for information systems and power electronic systems.

2.1.7. Lightning protection system LPS

The sum of air-termination devices, down conductors, grounding devices, surge protectors and other connecting conductors.

Note: In the third chapter of GB 50057-94 (2000 edition), air-termination devices, down conductors, grounding devices, and some measures against intrusion of lightning waves and lightning induction are called lightning protection measures and are divided into three categories. Chapter 4 lightning protection devices only include lightning receptors, down conductors, and grounding devices. This term refers to

Since Appendix 8 of this standard, surge protectors have also been included in lightning protection devices.

2.1.8. lightning protection zone LPZ

Areas where the electromagnetic environment of lightning strikes needs to be regulated and/or controlled.

Note: According to the different levels of lightning electromagnetic pulse, the space to be protected is divided into different lightning protection zones, characterized by the significant changes in the lightning electromagnetic environment (lightning current, lightning electromagnetic field), and each zone is calibrated as LZOA, LZOB, LPZ B 1 zone And subsequent areas (LPZ2, etc.). Generally, the larger the area code, the weaker the electromagnetic environment. in:

LPZ0A is a direct lightning non-protection zone, all kinds of objects in this area may be struck by lightning, electromagnetic

 The field is not attenuated and belongs to a completely exposed undefended area

 LPZ0B is a direct lightning protection zone. Various objects in this area are rarely struck by lightning. Electromagnetic B

 The field is still not attenuated and belongs to an exposed direct mine fortification zone

LPZ01 is the first lightning shielding protection zone. Various objects in this area cannot be directly struck by lightning.

The LPZ0B area is small and shielded by buildings, and the electromagnetic field in this area is initially attenuated. B

 LPZ2 is the second lightning shielding protection zone. Of course, all kinds of objects in this area cannot be directly struck by lightning.

With further reduction and other shielding measures, the electromagnetic field in this area is further attenuated

 You can also set up a more advanced lightning shielding protection zone LPZ3‥‥, etc.

2.1.9. Lightning equipotential bonding

Separate devices and various conductive objects are connected with equipotential bonding conductors or surge protectors to reduce the potential difference between them caused by lightning current.

Note: The surge protector only becomes a measure of equipotential connection under thunder and lightning.

2.1.10. Surge protective device

A device used to divide transient currents and limit transient voltages. It contains at least one non-linear protective element.

Note: "Surge protector" is a standard term in my country. In some documents, it is also called surge protector, overvoltage protector, lightning protection device,

These are non-Chinese standard terms. Whether the surge protector, which is mainly used to discharge the direct lightning current or a part of it, is called a "lightning arrester" is still under study.

2.1.11 voltage switching type SPD

When there is no surge, it has high impedance, and when there is a surge voltage, it can be converted into a low-impedance SPD immediately. The commonly used components include discharge gap, gas discharge tube, thyristor (silicon controlled rectifier) and triac. This type of SPD is sometimes called "crowbar SPD".

2.1.12 Voltage limiting type SPD voltage limiting type SPD

It has a high impedance when there is no surge, but its impedance continuously decreases as the surge current and voltage increase.

The commonly used components are: metal oxide varistors and transient suppression diodes. This type of SPD is sometimes called "clamped SPD".

2.1.13 Combination SPD combination SPD

An SPD composed of voltage switching elements and voltage limiting elements. According to the applied voltage and current, it can show the characteristics of voltage switch type or voltage limit type or both.

2.1.14 Metal oxide varistor (MOV) metal oxide varistor

Large-capacity non-linear resistance elements made of various metal oxide formulations are often used as protection elements for voltage-limited SPDs.

2.1.15 decoupler

In order to realize the SPD inter-stage coordination, the circuit components that need to be connected in series between the stages generally use inductive components in the power surge protection.

2.1.16 configuration of stages and location of SPD

Determination of the number of SPD levels and the location of each level of SPD in a surge protection scheme.

2.1.17 surge energy withstand capacity

The maximum impact energy or current that the SPD can withstand.

Note: The current capacity should be characterized by energy value, but for convenience in engineering, it can be characterized by the peak value of impulse current with specified waveform and specified number of times.

Generally speaking, the SPD of type I test is expressed as Iimp, the SPD of type II test is expressed as Imax, and the SPD of type III test is expressed as Uoc or Imax.


2.1.18 modes of protection

The power SPD module can be connected between the phase line to the phase line, the phase line to the ground, the phase line to the neutral line, the neutral line to the ground and various combinations. These connection methods are called protected modes.

Note: The commonly used protection modes are: ground protection mode (or common mode)-the module is connected between the phase line and the ground, the neutral line and the ground; the full protection mode-the module is connected between the phase line and the ground, the neutral line and the ground; Between the ground and between the phase line and the neutral line; "3+1" mode-the module is connected to the phase line and the neutral line

Between the center line and the ground line. The ground protection mode is also called the common mode mode. The SPD module is connected between the phase line and the neutral line in a differential mode.

2.1.19 Maximum continuous operating voltage Uc maximum continuous operating voltage Uc

The maximum root-mean-square voltage or DC voltage that is allowed to be continuously applied to the SPD. This value is the rated voltage of the SPD.

Note: The maximum continuous operating voltage Uc is of great significance to the voltage limited SPD. Exceeding Uc will cause the SPD to overheat, accelerate aging or even damage.

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