1. In terms of application fields, they can be categorized by voltage levels. The rated voltage of surge arresters ranges from <3kV to 1000kV, with low voltages at 0.28kV and 0.5kV. Surge protectors have a rated voltage of ≦1.2kV, 380, 220~10V~5V. The protected objects differ. Surge arresters protect electrical equipment, while SPD surge protectors typically safeguard secondary signal circuits or power supply circuits for electronic instruments and equipment. The insulation or voltage withstand levels vary. The voltage withstand levels of electrical and electronic equipment are not on the same scale, and the residual voltage of overvoltage protection devices should match the withstand level of the protected objects.

2. Different installation locations. The surge arresters introduced by WePower are generally installed on the primary system to prevent direct lightning wave intrusion, protecting overhead lines and electrical equipment; whereas SPD surge protectors are more commonly installed on the secondary system, serving as a supplementary measure after surge arresters have eliminated direct lightning wave intrusion, or when surge arresters have not completely eliminated the lightning waves. Therefore, surge arresters are mostly installed at the incoming line; SPDs are more frequently installed at the end of the outgoing lines or signal loops.

3. Different current-carrying capacities. Surge arresters, primarily designed to prevent overvoltage from lightning, generally have a larger relative current-carrying capacity. For electronic equipment, the insulation level is significantly lower than that of conventional electrical equipment, necessitating SPDs to protect against both lightning overvoltage and operational overvoltage. However, the current-carrying capacity of SPDs is usually not substantial. SPDs are typically installed at the end and do not directly connect to overhead lines. After passing through the current-limiting effect of the previous stage, the lightning current is already reduced to a lower level. Therefore, SPDs with a small current-carrying capacity can still provide adequate protection; the current rating is not as important as the residual voltage.

4. There are also significant differences in other insulation levels and focus points of parameters. Surge protectors are suitable for precise protection in low-voltage power supply systems. Various specifications can be chosen based on different AC and DC power sources. Due to the larger distance between the terminal equipment and the upstream surge protector, oscillating overvoltage or induction of other overvoltages may easily occur on this line. For precise surge protection at the terminal equipment, when used in conjunction with the upstream surge protector, the protection effect is even better.

5. Material Differences: The main material of surge arresters is typically zinc oxide (a type of metal oxide varistor), whereas the main material of surge protectors varies according to the surge protection level and classification protection (IEC 61312). Moreover, surge protectors are much more precise in design compared to ordinary lightning arresters. Technically, surge arresters do not meet the level of surge protectors in terms of response time, voltage limiting effect, overall protection performance, and resistance to aging.

6. In terms of nominal discharge current, the surge arrester specifications include discharge currents of 1.5kV, 2.5kV, 5kV, 10kV, and 20kV. Applications: Surge arresters are primarily used in power stations, transmission lines, sub-stations, power generation, capacitors, motors, transformers, neutral points, iron and steel smelting, and railways. Surge protectors are mainly used in low-voltage power distribution, cabinets, low-voltage electrical equipment, communication, signaling, stations, and machine rooms.

7. From the perspective of testing standards and requirements, surge protectors, due to their connection to the primary electrical system, require sufficient external insulation capabilities and are larger in appearance dimensions. In contrast, surge protectors connected to low voltage can be made much smaller, for instance, in terms of appearance volume. Surge protectors mainly consist of silicone rubber, ceramics, and iron cans, being large and heavy. Surge protectors, however, utilize a small amount of silicone, epoxy coatings, plastic casings, metal with ceramics, and metal with plastics.