Spark Gap

The spark gap is an indispensable safety device in cathodic protection systems, used to protect insulating joints (insulating flanges), CP test posts, pipelines and equipment from lightning over-voltage, switching over-voltage and fault-current impact damage. Under normal conditions the spark gap presents a high impedance and does not affect CP effectiveness; when an over-voltage (lightning, fault current, etc.) exceeds its breakdown voltage, the gap instantly conducts and dumps the energy to ground, protecting the insulating joint and pipeline. After the over-voltage disappears, the spark gap automatically returns to high-impedance state and CP resumes normal operation.

Key Technical Specifications

• DC spark-over voltage100 V / 250 V / 350 V / 500 V (selectable per joint rating)
• Nominal discharge current (8/20 μs)50 kA – 100 kA
• Maximum discharge current (8/20 μs)100 kA (single strike)
• Power-frequency withstand current≥ 50 A / 0.5 s
• Response time< 100 ns (nanosecond-level)
• Insulation resistance≥ 1000 MΩ
• Arc voltage≤ 40 V (residual after conduction)
• Operating temperature-40 °C to +70 °C
• Ingress protectionIP68 (fully sealed, direct-burial capable)
• Housing materialStainless steel / engineering nylon
• ConnectionM10 stud terminal / direct cable lug
• MountingInside EX-proof box / test post / direct burial

Product Advantages

• Precise over-voltage protection, stable and reliable discharge.
• Industrial-grade durability, fits complex field conditions.
• High-efficiency discharge, eliminates lightning hazards.
• Self-restoring operation, long-term maintenance-free.
• Multi-layer protection design, prevents breakdown failures.
• Easy installation, simple maintenance.

Typical Applications

• Insulating joint / flange protectionParallel-connected across insulating joints to prevent over-voltage breakdown and pipeline short-circuit.
• Long-distance pipeline CP systemsOil & gas trunk pipelines — CP test posts and insulating device protection.
• Tank-farm CP systemsProtects insulating devices and CP equipment between tanks and pipelines.
• Station inlet/outlet insulationPrevents lightning and fault current from entering the station via the pipeline.
• Stray-current drainageUsed together with drainage devices to protect against DC/AC stray-current interference.
• HV power-line parallel sectionsProtects pipelines paralleled or crossed with HV transmission lines from induced over-voltage.