5 Common Surge Arrester Failures and How to Diagnose Them

Your surge arresters are the silent guardians of your power system, deflecting lightning strikes and switching surges around your critical assets. But what happens when the guardian fails?

A failing arrester doesn’t just stop protecting; it can become a liability, leading to costly downtime, equipment damage, and even safety hazards. This guide breaks down the five most common surge arrester failures, equipping you with the knowledge to diagnose issues early and prevent them proactively.

Failure 1: Moisture Ingress – The Silent Killer of Insulation

When moisture penetrates the arrester housing, it compromises the internal insulation, leading to partial discharges and eventually, a flashover.

Why It Happens:

• Failed Seals: Especially common in porcelain-housed arresters due to cracking or aging.
• Poor Installation: Improperly sealed terminals allow humidity to seep in.
• Condensation:Rapid temperature changes in humid environments cause internal sweating.

How to Diagnose It:

• Key Metric:Monitor leakage current. A steady rise in the resistive component is a clear sign of internal moisture.
•  Standard Test:Use an MOA-R Metal Oxide Arrester Resistive Current Tester
• Measured leakage current is excessive.

Failure 2: Thermal Runaway – The Overheating Crisis

Metal Oxide Varistor (MOV) discs generate heat with each surge. If this heat doesn’t dissipate, it causes thermal runaway—degrading the MOV, leading to cracking, melting, and complete failure.

Tell-tale Signs:

• Discoloration or bulging of the polymer housing.
• Hot spots detected by an infrared camera.
• A gradual but steady increase in leakage current under normal operating voltage.

How to Prevent It:

• Regular Thermal Scans:Use infrared thermography during routine inspections to spot overheating units.
• Online Monitoring:Install devices that continuously track leakage current and temperature for real-time health assessment.

Failure 3: Surface Contamination & Tracking – The Environmental Threat

In industrial or coastal areas, pollutants form a conductive layer on the arrester surface. When damp, this layer can cause surface tracking and a flashover.

Common Culprits:

•     Industrial dust and chemical vapors.
•     Salt spray near coastlines.
•     Desert sand and airborne pollution.

Diagnosis & Solution:

•     Visual Inspection:Look for tracking marks, carbonized paths, or uneven dirt on the housing.
•     Right Product for the Environment: Choose arresters with higher creepage distance or silicone rubber housing for better pollution performance.

Failure 4: Mechanical Damage – The Hidden “Internal Injury”

Arresters may look rugged, but shocks from dropping or over-tightening during installation can create micro-cracks in the internal MOV discs.

Main Causes:

•     Impact during transportation or handling.
•     Over-tightening the mounting bolts.
•     Misalignment in multi-phase setups, creating mechanical stress.

Pre-commissioning Checklist:

• Thorough Visual Check: Ensure no cracks or physical damage.
• Follow Torque Specifications:Always use a torque wrench as per the manufacturer’s guidelines.
• Partial discharge testing can screen out defective arresters with cracked internal MOV discs.PD≤10PC The surge arrester meets all specifications.

Failure 5: Internal Short Circuit – The Critical Failure

Due to manufacturing defects, severe aging, or extreme overvoltages, the arrester can short internally, becoming a direct path to ground.

Emergency Symptoms (Act Immediately):

•   The arrester disconnector (if equipped) operates
•   An audible buzzing or humming sound during operation.
•   Circuit breakers tripping or fuses blowing on the associated line.

How to Confirm:

• De-energize and isolate the arrester immediately.
• Perform a DC Reference Voltage (U_1mA) test. If the measured current is far beyond specs or voltage cannot be established, the unit has shorted and must be replaced.

Beyond Repair: Best Practices for a Proactive Defense

Smart maintenance isn’t about fixing failures; it’s about preventing them. Build a robust defense with these strategies:

1.Quality First:Source products certified to IEC 60099-4, the international standard for surge arresters.

2.Smart Monitoring:Install surge counters and online monitoring devices to track activity and analyze leakage current trends.

3.Predictive Maintenance:Establish a schedule that combines infrared scanning and leakage current testing to predict end-of-life.

4.Scheduled Replacement:Plan for replacement every 8-10 years, or more frequently in areas with high lightning density.

The online monitor enables condition-based maintenance for high-voltage arresters by recording lightning and switching surge events, and by detecting the increased leakage current that signals insulation degradation.

An ideal solution for high-voltage grids and remote areas (e.g., suburbs, mountains) is the use of smart online monitors, which enhance reliability by enabling real-time condition monitoring and predictive maintenance of surge arresters.

Looking for a Reliable Surge Protection Solution for Your Project?

Zhejiang Goto Electrical Co., Ltd. specializes in manufacturing polymer and porcelain-housed Zinc Oxide surge arresters. Our products, available with optional disconnectors, surge counters, and smart monitoring units, are all tested to IEC standards.

Contact our technical expert team today for a customized solution and product recommendation tailored to your specific application.