I. Definition 1. Lightning arrester Lightning arrester is a device that protects the substation from lightning surges. When lightning surges passing through substations along the line exceed the arrester protection level, the arrester discharges first, and the lightning current is safely led to the earth through good conductors. The grounding device is used to limit the lightning voltage amplitude below the lightning impulse level of the protected equipment. Electrical equipment is protected.

2. The surge protector, also called lightning arrester, is a device that provides security protection for various electrical equipment, instrumentation, and communication lines. When a sudden current or voltage suddenly occurs in an electrical circuit or a communication line due to external interference, the surge protector can conduct the shunt in a very short time, thereby avoiding damage to the other devices in the circuit by the surge.

As can be seen from the following information, surge protectors are also a kind of surge protector, but there are big differences.

2. Comparison between lightning arrester and surge protector Lightning arrester refers to a lightning arrester of a building and forms a Faraday cage together with a lightning rod, a ground bar, etc. to prevent the building from being damaged. The basic principle of the lightning arrester is to introduce a lightning impulse electromagnetic pulse (LEMP) into the ground for digestion. . But why is there still a lot of buildings and their equipment inside are damaged by lightning after the installation of arresters?

First, the wire of the arrester is made of copper-iron alloy, so its wire performance is limited, and its response speed is only 200 microseconds (uS). The half-peak speed (maximum energy) of the LEMP is 20 microseconds (uS), which means that the speed of the LEMP is faster than that of the lightning arrester. In this way, after the lightning arrester directs the first direct lightning strike to the ground, it tends to react to the secondary lightning and the third lightning. However, direct leaks hit the device. In other words, the arrester has little effect on secondary and triple thunder.

Second, after LEMP is introduced into the ground, it will return from the ground to form an induction mine. Inductive lightning leaks from all metal-containing wires to equipment (network cables, power cables, signal cables, transmission cables, etc.). Because the lightning arrester is one-way, it does not work for inductive lightning. Inductive lightning can directly damage the equipment. What's more, lightning conductors are often not installed on the conductors.

Once again, only 20% of the surges come from external environments such as lightning strikes and 80% from the inside of the system. Arresters do not have any effect on this 80%.

According to the analysis to answer the difference between surge protectors (SPD, some known as surge protectors) and arresters:

1, the scope of application of different (voltage): a wide range of arresters, there are many voltage levels, generally from 0.4kV low pressure to 500kV ultra high pressure (see the analysis of the upper floors), and SPD generally refers to the use of over-voltage protection devices below 1kV;

2. Different objects to be protected: The lightning arrester protects the electrical equipment, and the SPD surge protector generally protects the secondary signal circuit or the electronic power supply instrument and other terminal power supply circuits.

3, insulation level or pressure level is different: Electrical equipment and electronic equipment pressure level is not an order of magnitude, the residual voltage of the overvoltage protection device should be matched with the pressure level of the protection object.

4, different installation locations: Arrester is generally installed on a system to prevent the direct intrusion of lightning waves to protect overhead lines and electrical equipment; and SPD surge protectors are installed in the secondary system, is to eliminate the lightning wave in the arrester After the direct intrusion, or when the arrester does not remove the lightning wave cleanly, the arrester is installed at the entrance; the SPD is usually installed at the terminal outlet or signal loop.

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