Electrical systems today, from residential setups to large-scale industrial plants, face continuous risks from voltage surges caused by lightning strikes, switching operations, and grid disturbances. These surges can damage sensitive equipment, shorten system lifespan, and lead to costly downtime. To mitigate these risks, engineers rely on Surge Arresters—devices designed to safeguard electrical infrastructure by limiting overvoltages.
A Surge Arrester is a protective device that diverts excessive voltage surges safely to the ground, preventing them from damaging electrical equipment. Its main function is to limit overvoltage levels to a safe threshold.
Industrial: Protects high-value equipment like motors, switchgear, and transformers.
Commercial: Ensures uninterrupted power supply for offices, malls, and data centers.
Residential: Guards home appliances and electronic devices from lightning surges or unstable power supply.
Under standard operating voltage, the surge arrester remains inactive, offering minimal leakage current.
When a surge occurs (e.g., from lightning or switching operations), the arrester immediately provides a low-resistance path to ground, discharging the excess energy safely.
Surge arresters use non-linear resistance materials like Metal Oxide Varistors (MOVs). These resistors allow negligible current under normal conditions but conduct heavily when voltage exceeds a threshold, providing instant protection.
Surge arresters differ by the technology used inside them.
Most widely used.
Uses zinc oxide blocks.
Offers high energy absorption capacity and fast response.
Older technology.
Requires series spark gaps for insulation.
Less common today due to lower efficiency compared to MOA.
Used in households and commercial buildings to protect appliances and low-voltage systems.
Commonly found in distribution systems, substations, and industrial facilities.
Installed in transmission networks and power stations to protect large-scale equipment from lightning and switching surges.
Provides essential protection for substations, transmission lines, and distribution networks.
Shields electrical systems against direct and indirect lightning strikes.
Data centers and hospitals where reliability is critical.
Factories with heavy machinery vulnerable to surges.
Prevents costly damage and ensures system stability in all types of equipment.
Surge Arrester: Protects against all types of overvoltage (lightning, switching surges, temporary overvoltage).
Lightning Arrester: Primarily designed to protect structures and equipment from direct lightning strikes.
Surge arresters are broader in scope, while lightning arresters are specific to lightning-related risks.
Lightning arrester: Installed on transmission towers and buildings.
Surge arrester: Installed inside substations, switchgear, and near sensitive equipment.
Used in power grids, substations, and distribution networks.
Used in homes and offices to protect electronic equipment like computers, TVs, and routers.
| Feature | Surge Arrester | Surge Protector |
| Application | High/medium-voltage power systems | Low-voltage electronics and appliances |
| Protection scope | Lightning, switching surges, grid faults | Plug-level voltage spikes |
| Typical installation | Substations, switchgear, transformers | Power strips, sockets |
Install as close as possible to the equipment being protected (e.g., transformers, switchgear).
A low-resistance ground connection is crucial for safely diverting surge energy.
Regularly inspect arresters for cracks or wear.
Replace units that have absorbed multiple surge events.
Ensure grounding resistance remains within standards.
Shields critical assets from costly damage.
Reduces downtime and ensures smoother operation of power networks.
Minimizes repair and replacement expenses in the long term.
Q1: What is the main function of a surge arrester?
To protect electrical systems by limiting overvoltages and diverting surge currents safely to the ground.
Q2: Where are surge arresters installed?
They are commonly installed in substations, on transmission lines, and near transformers and switchgear.
Q3: What is the difference between a surge arrester and a lightning arrester?
A surge arrester protects against multiple types of overvoltage, while a lightning arrester is specifically for direct lightning strikes.
Q4: Can surge arresters be used in residential systems?
Yes, low-voltage surge arresters are used to protect home appliances and electronics.
Q5: Do surge arresters need maintenance?
Yes. Regular inspection and grounding checks are recommended to ensure reliable performance.
In modern electrical systems, surge arresters play a vital role in protecting infrastructure from overvoltage caused by lightning, switching operations, and grid disturbances. Understanding what a surge arrester is, how it works, and the types available helps engineers and facility managers choose the right solution for their systems.
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