What is Lightning Arrester?

  1. Lightning Arrester (Surge Arrester)

This is an overvoltage limiter. When an overvoltage occurs, the voltage between the two terminals of the arrester does not exceed the specified value, preventing electrical equipment from being damaged by the overvoltage. Once the overvoltage has passed, it allows the system to quickly return to normal.

  1. Valve Sheet

A resistor sheet with nonlinear volt-ampere characteristics. When overvoltage occurs, it exhibits low resistance, thereby limiting the voltage on the arrester. Under normal working frequency voltage, it exhibits high resistance, limiting the current passing through the arrester.

  1. Rated Voltage of Lightning Arrester

This is the maximum allowable effective value of the working frequency voltage applied between the terminals of the arrester. The arrester designed according to this voltage can work correctly under the temporary overvoltage in the specified action load test. It is an important parameter that indicates the operating characteristics of the arrester. However, it is not equal to the rated voltage of the system.

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Differences between Surge Protectors and Lightning Arresters

  1. The Application Fields Can Be Divided Based on Voltage Levels.

The rated voltage of the arrester ranges from less than 3kV to 1000kV, with low voltage being 0.28kV, 0.5kV. The rated voltage of the surge protector is less than or equal to 1.2kV, 380V, 220V to 10V~5V.

  1. Different Protection Objects

The lightning arrester is for protecting electrical equipment, while the SPD surge protector is generally for protecting secondary signal circuits or power supply circuits for electronic instruments and meters.

  1. Different Insulation Levels or Withstand Voltage Levels

The withstand voltage level of electrical equipment and electronic equipment is not on the same order of magnitude. The residual voltage of the overvoltage protection device should match the withstand voltage level of the protected object.

  1. Different Installation Locations

Lightning arresters are generally installed in primary systems to prevent the direct intrusion of lightning waves and protect overhead lines and electrical equipment. SPD surge protectors are installed more on secondary systems and serve as supplementary measures when the arrester has eliminated the direct intrusion of lightning waves or when the arrester has not completely eliminated the lightning waves. Therefore, lightning arresters are often installed at the entrance; SPDs are often installed at the end of the line or signal loop.

  1. Different Flow Capacities

The lightning arrester, mainly acting to prevent lightning overvoltages, has a relatively large flow capacity. As for electronic equipment, its insulation level is much smaller than that of general electrical equipment, so SPD is needed to protect against lightning overvoltage and operating overvoltage, but its flow capacity is generally not large.

  1. Surge Protectors Are Suitable for Fine Protection of Low-Voltage Power Supply Systems.

The power supply surge protector is suitable for fine surge protection of terminal equipment. When used in combination with the previous surge protector, the protection effect is better.

  1. Different Materials

The main material of the lightning arrester is zinc oxide (a type of metal oxide varistor), while the main material of the surge protector varies according to the surge resistance level and graded protection (IEC61312), and its design is much more precise than ordinary lightning arresters.

8.Technically Speaking, Lightning Arresters Cannot Achieve the Level of Surge Protectors in Response Time, Voltage Limitation Effect, Comprehensive Protection Effect, and Anti-Aging Characteristics.

9.Nominal Discharge Current

For lightning arresters, nominal discharge currents (In) range from 1.5kV, 2.5kV, 5kV, 10kV, to 20kV. These are based on an 8/20us nominal lightning current. For surge protectors, nominal discharge currents range from 5kA, 10kA, 0.5kA, 20kA, 30kA, and can reach up to 120kV.

10.Testing Standards and Requirements

The testing standards and requirements for these two devices are quite different. Because lightning arresters are connected to the primary electrical system, they need to have excellent external insulation properties. This often results in a larger size. Surge protectors, on the other hand, are connected to low voltage systems and can be made much smaller. In terms of appearance and size, lightning arresters are usually made of silicone rubber, ceramic, or metal cans, making them larger and heavier. Surge protectors often use small amounts of silicone, epoxy encapsulation, plastic cases, and combinations of metal and ceramic or metal and plastic.

11.Usage

Lightning arresters are primarily used in power stations, power lines, distribution stations, power generation, capacitors, motors, transformers, neutral points, steel making, and railways. Surge protectors are mainly used in low voltage distribution, cabinets, low voltage appliances, communication, signal, workstations, and server rooms.

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Conclusion

The nominal discharge current (In) is an important parameter for both surge protectors and lightning arresters. For surge protectors, this parameter is defined as the peak value of the current through the surge protector when it is subjected to a 8/20μs waveform impulse current injection. The standard nominal discharge current values are 5kA, 10kA, 20kA, 40kA and so on. The nominal discharge current value chosen should match the expected surge current level in the application.

For lightning arresters, the nominal discharge current is defined similarly. However, these devices are designed to handle much higher surge currents than surge protectors due to their typical application in high voltage power systems. Therefore, the nominal discharge currents for lightning arresters are significantly higher than those for surge protectors.

To summarize, while surge protectors and lightning arresters serve similar purposes of protecting electrical and electronic equipment from overvoltages, they are designed for different applications and thus have different characteristics and specifications. Surge protectors are typically used for lower voltage applications and are designed to protect sensitive electronic equipment, while lightning arresters are used for higher voltage applications and are designed to protect power system equipment from lightning surges and other high magnitude surges.