Why High Pressure Gas Builds Up Inside A Lightning Arrester？

Internal high-temperature and high-pressure gases form inside a lightning arrester when severe moisture ingress or prolonged overvoltage causes internal electrical tracking. This degradation creates a continuous localized arc, vaporizing internal components and creating intense pressure that can result in catastrophic housing failure if left unaddressed.

Substation equipment faces severe stress during atmospheric discharges. When a lightning surge arrester experiences moisture penetration through degraded seals, the internal dielectric strength drops rapidly. This moisture triggers partial discharges along the internal valve elements, transforming normal electrical stress into localized thermal energy that rapidly expands trapped air pockets.

Thermal Degradation Mechanisms in Power Networks

Overheating accelerates rapidly when continuous system voltage passes through compromised surge arresters. The internal zinc oxide varistors experience thermal runaway, escalating current leakage. This continuous electrical conduction generates extreme temperatures, which vaporize sealing compounds and internal fiberglass structural elements, generating high-volume gases within the sealed porcelain or polymer housing.

Operational Limits of Standard Units

Different voltage classifications exhibit distinct failure thresholds during insulation breakdowns. A standard 11kv lightning arrester possesses less internal volume, meaning pressure accumulation happens significantly faster than in larger units, making prompt thermal imaging inspections essential for grid safety.

Risk Assessment and Failure Manifestations

Uncontrolled gas accumulation alters the physical stability of protective equipment. Technicians must recognize specific physical indicators during routine field inspections to prevent total insulation breakdown across the distribution network:

1. Moisture indicators showing seal compromise near the base terminals.

2. Discoloration or micro-cracks along the external silicone rubber sheds.

3. Audible corona humming or buzzing under standard dry weather conditions.

Higher voltage equipment, such as a 15kv lightning arrester, requires rigorous monitoring because the stored energy during a thermal fault is substantially higher. Increased internal pressure can breach structural relief vents, venting ionized gases into adjacent substation components and causing secondary phase-to-phase short circuits.

Pressure Indicators and Maintenance Metrics