Surge Protection Device versus Lightning Arrester
As the common part of the electrical device, both the surge protection device and lightning arrester have the function of preventing from over-voltage, especially preventing from the lightning over-voltage. However, the two of surge protection device and lightning arrester have great differences.
Different voltage level from the perspective of application field
The rated voltage of the lightning arrester ranges from 3kV to 1000kV. The low voltage is 0.28kV, 0.5kV. However, the rated voltage of the surge protection device is no more than 1.2kV, such as 380V, 220V, etc.
Different protecting objects
The lightning arrester is used to protect the electrical appliance. However, surge protection device (SPD) generally protects the secondary signal loop or the end power supply loop of the electronic instrument.
Different insulation level or withstand voltage level
The withstand voltage level between them is not at the same magnitude level. The residual voltage of the over-voltage protective equipment should match with the withstand voltage level of the protection object.
Different installation position
The lightning arrester is generally installed on the first system, preventing from the direct invasion of the lightning wave and protecting the overhead line and electrical appliance. However, surge protection device is normally installed on the secondary system. It is a supplementary measure after the lightning arrester eliminates the direct invasion of the lightning wave, or the lightning arrester fails to eliminate all lightning wave. Therefore, the lightning arrester is normally installed on the wire inlet. SPD is mostly installed on the terminal outlet or signal loop.
Different discharge current capacity
Because the main function of the lightning arrester is to prevent from the over-voltage of the lightning, its relative discharge current capacity is high. However, as to the electronic device, its insulation level is far lower than the electrical device of the general significance. Therefore, SPD is required to prevent from the lightning over-voltage and operation over-voltage. But its discharge current capacity is normally not high.
Surge protection device (SPD) is usually used in the terminal. It will not be connected with the overhead line directly. After going through the primary current limiting function, the lightning current has been limited to a lower value. In such a manner, SPD with not high discharge current capacity can completely play a protective role. The through-flow value is not important, but the residual voltage. Surge protection device is suitable for the accurate protection of the low-voltage power supply system. Because of the great distance between the terminal equipment and the preceding surge protection device, the circuit of the surge protection device is easily to generate vibration over-voltage or perceive other over-voltages. It is applicable to the precision power supply surge protection of the terminal equipment. Once equipped with the preceding surge protection device, the protection effect is better.
The main material of the lightning arrester is the zinc oxide (one kind of metallic oxide rheostat). However, the main material of the surge protection device is different on the basis of the different levels and classified protections (IEC61312) of the surge resistance. In addition, the SPD design is more precision than the ordinary lightning arrester.
In addition, from the perspective of the technology, lightning arrester fails to reach the level of the surge protection device from the perspectives of the response time, voltage limiting effect, comprehensive protection effect, anti-aging performance and so on.
Because the lightning arrester is connected with the primary electrical system, there must be enough external insulation performance and big appearance size. However, since the surge protection device is connected with the low voltage, its size can be made very small. For instance, from the perspective of the appearance size, the main materials of the lightning arrester include silicone rubber, ceramics and iron can, thus having a big size and heavy weight. However, the surge protective surge is mainly made of few silica gels, epoxy package, plastic casing, metal and ceramics, metal and plastics.
Lightning arrester is mainly used in the electrical station, circuit, power distribution state, power generation, capacitor, motor, transformation electrical appliance, neutral point, steel smelting and railway. The surge protection device is mainly used in the low-voltage power distribution, cabinet, low-voltage electrical appliance, communication, signal, machine station and machine room.