5 Common Surge Arrester Failures and How to Diagnose Them

When it comes to protecting power systems from lightning and switching surges, surge arresters are your first line of defense. However, like all electrical devices, they can degrade or fail over time — especially under harsh operating conditions in renewable energy systems, substations, or transmission networks. Understanding the common surge arrester failures and knowing how to diagnose them early can prevent costly downtime, equipment damage, and potential safety hazards. Let’s break down the five most common causes of surge arrester failure and what you can do about them.

1.Moisture Ingress and Insulation Breakdown

One of the most frequent causes of surge arrester failure is moisture ingress. When water or humidity penetrates the arrester housing, it compromises the internal insulation, causing partial discharge and eventually flashover.

Common Causes

• Damaged or poorly sealed housing (especially in porcelain types)
• Improper installation or lack of weatherproofing
• Condensation during rapid temperature changes

How to Diagnose

Use an insulation resistance test or leakage current measurement. An increase in leakage current indicates internal moisture contamination.

2.Thermal Overload and Aging of Metal Oxide Discs

Thermal runaway is another major cause of arrester failure. Each surge event generates heat in the MOV (Metal Oxide Varistor) blocks. If the arrester doesn’t cool down properly, the continuous stress can cause thermal degradation, leading to cracking or partial melting.

Typical Symptoms

• Discoloration or deformation of housing
• Gradual increase in leakage current
• Elevated surface temperature around the core

How to Diagnose

Infrared thermography or continuous temperature monitoring can detect overheating before failure occurs. If you notice a steady rise in leakage current even under normal voltage, it’s time for replacement or testing.

3.Contamination and Surface Tracking

In industrial or coastal environments, pollution can form conductive layers on the surface of an arrester. When damp, these layers create leakage paths, leading to surface tracking and flashover.

Common Pollutants

• Industrial dust and chemical vapors
• Salt spray near coastal regions
• Desert sand or smog particles

How to Diagnose

Visual inspection during maintenance is key.

Look for:

• Burn marks or carbonized streaks
• Uneven surface coloration
• Corona discharge under night observation

4. Mechanical Damage and Improper Handling

Surge arresters may look sturdy, but mechanical stress during transportation or installation can damage internal components.

Typical Causes

• Dropping the arrester before installation
• Over-tightening mounting bolts
• Misalignment in multi-phase installations

Even small cracks in the ZnO blocks can cause partial discharge, leading to premature failure under voltage stress.

How to Diagnose

Use partial discharge testing or visual inspection before energizing new arresters. Always check the manufacturer’s torque and installation guidelines.

5. Internal Short Circuit and Overvoltage Stress

In rare cases, repeated overvoltages or internal defects may lead to internal short circuits — where the arrester fails to block voltage, becoming conductive even at normal operation.

Causes

• Prolonged overvoltage conditions
• Degraded MOV blocks
• Manufacturing defects (if low-quality materials used)

Symptoms

• Persistent high leakage current
• Audible humming or buzzing
• Tripped circuit breakers or blown fuses

How to Diagnose

• Disconnect the arrester and perform a DC leakage test.
• If the reading is higher than rated limits, replace the unit immediately.
• Use a surge counter (like JS8 type) to monitor surge activity and anticipate wear-out cycles.

How to Prevent Future Failures

While no surge arrester lasts forever, proper maintenance and monitoring can extend lifespan dramatically.

Best Practices for Longevity

• Choose IEC 60099-4 certified ZnO arresters from trusted suppliers.
• Install surge counters to monitor lightning activity.
• Inspect housing and terminals annually for cracks or corrosion.
• Replace units every 8–10 years, depending on lightning density.
• Use harmonic elimination devices (LXQ type) to stabilize voltage in inverter-based systems.

Why Quality Matters in Business Procurement

In large-scale renewable or utility projects, one arrester failure can disrupt entire systems.

Choosing reliable, IEC-certified surge arresters ensures:

• Consistent protection across multiple sites
• Lower total cost of ownership
• Fewer unplanned maintenance visits
• Extended lifespan of transformers and switchgear

Zhejiang Goto Electrical Co., Ltd. manufactures polymer and porcelain Zinc Oxide surge arresters with optional disconnectors, surge counters, and harmonic devices — all tested under IEC 60099-4 standards.

Conclusion

Surge arrester failures are not random — they leave visible and measurable signs. By understanding what causes them and how to diagnose issues early, you can save your system from expensive repairs and ensure continuous, stable power delivery.

From moisture ingress to thermal overload, every failure mode teaches one lesson: choose quality, monitor regularly, and plan maintenance before it’s too late. Contact Us or visit Goto’s technical team for custom solutions designed for renewable energy systems and transmission protection.