In electrical systems, ensuring the protection of equipment from electrical surges and lightning strikes is crucial for maintaining the safety and longevity of devices. Surge arresters and lightning arresters are two critical components used to safeguard electrical systems from these threats. However, understanding the difference between lightning and surge arrester is essential.
In this guide, we will explore the key differences between surge arresters and lightning arresters, examining their definitions, functions, installation locations, and applications. By the end of this article, you will have a clear understanding of which device is best suited for your specific needs, whether you’re designing an electrical system or protecting sensitive equipment.
A surge arrester is a device designed to protect electrical equipment from transient overvoltages or electrical surges caused by switching actions, lightning strikes, or other sudden disturbances. These surges can damage sensitive components if not properly diverted. Surge arresters operate by offering a safe path for surge current diversion, preventing it from reaching the connected equipment.
Surge arresters typically use metal oxide varistors (MOVs) to clamp transient voltages to a safe level, ensuring that electrical systems remain stable. They are commonly installed in low-voltage and medium-voltage systems, offering protection for telecommunication towers, consumer electronics, and industrial machinery. Surge protection devices (SPDs) are often used in these applications to protect against the risks of electrical surge damage. Surge arresters are designed following standards like IEC 60099-4, ensuring their effectiveness and safety under international guidelines.
A lightning arrester, on the other hand, is primarily designed to protect electrical systems from the direct effects of lightning strikes. When lightning strikes, the arrester provides a low-resistance path for the lightning current to be safely diverted to the ground, preventing the system from being overwhelmed by the surge.
Lightning arresters are often found in high-voltage systems, such as those used in power transmission lines, substations, and industrial plants. They are equipped with a spark gap or air-gap to handle the intense flashover voltage caused by lightning. Unlike surge arresters, which are used for smaller surges, lightning arresters are designed to handle much larger, instantaneous electrical surges generated by lightning. Lightning arresters are developed in compliance with standards like IEEE C62.11, which provide specifications for their design and application in high-voltage systems.
Surge arresters are equipped with MOVs, which change their resistance in response to transient voltages. Under normal conditions, the resistance is high, but when a surge occurs, it becomes low, offering a grounding system for the transient voltage. Surge arresters are particularly useful for protecting against smaller but frequent surges, such as those caused by electrical equipment turning on and off or power grid fluctuations.
This functionality is tested in accordance with IEC 60099-4, ensuring that surge arresters meet the required energy absorption and voltage clamping standards.
| Attribute | Surge Arrester | Lightning Arrester |
| Primary Protection | Protects against transient overvoltages (small surges) | Protects against lightning strikes (high energy) |
| Energy Dissipation | Absorbs 50 J to 200 J per surge | Absorbs 100 J to 1000 J per lightning strike |
| Peak Discharge Current | 10 kA to 40 kA | 100 kA to 200 kA or more |
| Flashover Voltage | 5 kV to 15 kV | 50 kV to 250 kV |
| Response Time | Microseconds | Instantaneous |
| Leakage Current | < 1 mA (normal operation) | < 10 μA (normal operation) |
| MCOV | Rated typically at 3 kV to 10 kV for medium voltage systems | Rated typically at 30 kV to 250 kV for high voltage systems |
| Continuous Operating Voltage (Uc) | Rated typically at 3 kV to 10 kV for medium voltage systems | Rated typically at 30 kV to 250 kV for high voltage systems |
| Impulse Current (Iimp) | Impulse current typically around 10 kA to 40 kA | Impulse current typically around 100 kA to 200 kA or more |
In contrast, lightning arresters are designed to protect against much higher voltage levels, typically from lightning strikes. When lightning strikes, the arrester provides a low-resistance path for the lightning to flow through. The energy is diverted to the ground through the arrester, safeguarding transformers, high-voltage systems, and electrical infrastructure.
Surge Suppression: Lightning arresters are specialized for handling high-current surges generated by lightning. They have a flashover voltage that allows them to discharge safely.
Leakage Current Protection: A key feature of lightning arresters is their ability to handle leakage current, ensuring the system remains safe after the lightning strike.
Energy Dissipation: The energy from the lightning strike is absorbed and dissipated through the arrester to minimize the risk of equipment failure.
Lightning arresters, as specified in IEEE C62.11, are designed to withstand the large current levels generated by lightning strikes, and their specifications cover their operational limits in such extreme conditions.
Surge arresters are commonly installed in low-voltage and medium-voltage electrical systems. Some typical installation locations include:
For optimal performance, surge arresters should be installed close to the equipment being protected, and grounding must be properly implemented to ensure safe surge current diversion.
Lightning arresters are primarily used in high-voltage systems, such as power transmission lines and substations. They are often installed at elevated points in buildings, particularly tall structures like skyscrapers, to provide lightning strike protection.
Key installation factors include:
Surge arresters are used in a variety of applications to protect against transient overvoltages, including:
Lightning arresters are used in applications where direct lightning strikes pose a significant risk, such as:
Electrical power stations, where high-voltage systems need to be protected from lightning-induced damage.
Industrial plants and substations that are exposed to lightning risks.
Wind turbines and solar farms, where the height of the structures makes them more susceptible to lightning strikes.
In conclusion, both surge arresters and lightning arresters are crucial components in safeguarding electrical systems, but they serve distinct purposes tailored to different types of electrical threats. Surge arresters are specifically designed to protect systems from transient overvoltages, which are typically caused by smaller, more frequent surges such as switching events, power fluctuations, and other temporary voltage spikes. These devices help to absorb excess energy and protect sensitive equipment from minor disruptions.
Lightning arresters are built to handle the extreme and high-energy surges that occur during lightning strikes. They offer vital protection for high-voltage systems by diverting the massive surge of energy caused by lightning safely to the ground, preventing catastrophic damage to both electrical infrastructure and connected equipment.
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