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.
To understand the difference between surge arrester and lightning arrester, we need to understand their respective definitions and know clearly what they are.
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.
When discussing surge arresters, two important parameters are often mentioned — MCOV (Maximum Continuous Operating Voltage) and Uc (Continuous Operating Voltage). Although they may sound similar, their meanings are not the same:
MCOV: Represents the maximum short-term continuous voltage that the surge arrester can tolerate without flashover or insulation breakdown. It is usually slightly higher than Uc and reflects the arrester’s ability to handle brief overvoltage conditions.
Uc: Refers to the long-term rated operating voltage under which the surge arrester can operate safely and continuously without overheating or degrading.
Engineering Tip:
When selecting a surge arrester, always make sure that Uc ≥ the maximum system operating voltage. If Uc is lower than the system voltage, the arrester will be exposed to continuous electrical stress, which can result in increased leakage current, thermal runaway, and premature ageing of the device.
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 play a vital role in protecting electrical systems. But they are not the same. The difference between lightning and surge arrester is clear: surge arresters protect against small, frequent overvoltages, while lightning arresters are designed for the extreme energy of a lightning strike.
Surge arresters are ideal for handling switching surges, power fluctuations, and other short spikes. They absorb excess energy and keep sensitive equipment safe.
Lightning arresters, in contrast, deal with high-voltage lightning currents. They safely divert this energy to the ground, protecting transformers, substations, and tall structures from catastrophic damage.
Understanding the surge arrester and lightning arrester difference helps engineers, contractors, and facility managers choose the right device. Surge arresters improve reliability in low- and medium-voltage systems, while lightning arresters are essential for high-voltage networks exposed to lightning risks.
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