Construction and Working of Metal Oxide Surge Arresters

Submitted by Kristian on Tue, 04/16/2024 - 15:37
Metal Oxide Surge Arresters

In the realm of electrical engineering, the protection of equipment and infrastructure from transient voltage spikes is paramount. One of the pivotal innovations in this field is the Metal Oxide Surge Arrester (MOSA). Developed by Swartz Engineering, MOSAs stand as robust guardians against the destructive forces of surges in power systems. Let's delve into the intricate construction and working principles behind these remarkable devices.

Understanding Surge Arresters

Surge arresters are essential components in power systems designed to divert excess voltage away from sensitive equipment. They serve as a crucial line of defense against transient overvoltages caused by lightning strikes, switching operations, or other disturbances in the grid.

Traditionally, surge arresters were made using silicon carbide or gapped carbon materials. However, the advent of Metal Oxide Surge Arresters revolutionized the landscape due to their superior performance, compact design, and extended lifespan.

The Construction of Metal Oxide Surge Arresters

Swartz Engineering employs advanced manufacturing techniques to construct MOSAs with precision and reliability. The fundamental components of a MOSA include:

1. Metal Oxide Varistor (MOV) Discs

   At the core of every MOSA lies the Metal Oxide Varistor (MOV) discs. These discs consist of zinc oxide (ZnO) grains mixed with other metal oxides, carefully formulated to exhibit non-linear voltage-current characteristics. MOV discs are stacked inside the arrester's housing to accommodate various voltage ratings.

2. Polymeric Housing

   Surrounding the MOV discs is a polymeric housing engineered to provide insulation and mechanical support. This housing is designed to withstand extreme environmental conditions, ensuring the longevity of the surge arrester.

3. Metallic End Fittings

   To facilitate electrical connections, metallic end fittings are attached to the arrester housing. These fittings not only serve as terminals but also provide mechanical support and ensure proper grounding of the device.

Metal Oxide Surge Arresters




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Working Principle of Metal Oxide Surge Arresters

When the power system experiences a surge in voltage, the MOV discs within the surge arrester swiftly respond to the increased voltage. Under normal operating conditions, the MOV exhibits a high impedance, allowing negligible current flow. However, when subjected to a surge exceeding a certain threshold, the MOV's impedance rapidly decreases, effectively shunting the excess energy to ground.

This dynamic response of the MOV discs ensures that the voltage across the protected equipment remains within safe limits, preventing damage or malfunction. Once the transient voltage subsides, the MOV returns to its high-impedance state, ready to respond to subsequent surges.

Advantages of Metal Oxide Surge Arresters

1. High Energy Absorption Capacity

   MOSAs offer superior energy absorption capabilities compared to traditional surge arresters, making them highly effective in protecting sensitive equipment.

2. Fast Response Time

   Thanks to their non-linear voltage-current characteristics, MOSAs respond swiftly to transient overvoltages, minimizing the risk of equipment damage.

3. Long Service Life

   The robust construction and high-quality materials used in MOSAs contribute to their extended service life, providing reliable protection for years to come.

4. Compact Design

   Metal Oxide Surge Arresters boast a compact and lightweight design, making them easy to install and suitable for various applications, including distribution networks and substations.


Metal Oxide Surge Arresters



The ultimate solution for reliable power control! call us at 276-285-3841

Applications of Metal Oxide Surge Arresters

Metal Oxide Surge Arresters find widespread use in a multitude of applications, including:

  • Protection of power transformers
  • Safeguarding distribution lines and substations
  • Shielding sensitive electronic equipment
  • Securing communication networks against lightning-induced surges


In conclusion, Metal Oxide Surge Arresters engineered by Swartz Engineering represent a pinnacle of innovation in the realm of surge protection. With their robust construction, swift response time, and unparalleled performance, MOSAs stand as indispensable guardians of electrical infrastructure worldwide. By understanding the intricacies of their construction and working principles, engineers can harness the full potential of MOSAs to safeguard critical equipment and ensure the reliability of power systems for generations to come.

Contact Us Today!

Ready to safeguard your electrical infrastructure with the latest in surge protection technology? Contact Swartz Engineering today to learn more about Metal Oxide Surge Arresters and how they can enhance the resilience of your power systems. Don't wait until it's too late – protect your equipment and ensure uninterrupted operation with Swartz Engineering's cutting-edge solutions. Reach out now to secure your peace of mind.

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