Class I surge arrester 3EL series

for electrical networksfor harsh environmentsvaristor

Overview
High-voltage surge arresters are protective devices designed to shield electrical power systems from transient overvoltages caused by lightning strikes, switching operations and other disturbances by diverting surge currents to ground and limiting voltage spikes to safe levels. Siemens Energy provides a comprehensive portfolio of surge arrester solutions including silicone rubber and porcelain designs for applications from medium to ultra-high voltage.

Key functions and features

• Overvoltage protection: rapidly divert transient voltage peaks to safeguard electrical systems
• Equipment safety: prevents insulation failure and extends asset lifetime
• System reliability: minimizes downtime and maintenance costs
• High mechanical stability: designed for support applications and regions with high seismic activity

Product family highlights

• 3EL silicone rubber surge arresters (Cage Design™): silicone rubber housing molded directly onto MOVs with an FRP rod cage for high mechanical strength; hydrophobic, UV-resistant, fire-retardant and self-extinguishing silicone; arc discharge behavior that avoids ejection of internal parts; suitable as station or line arresters; voltage capability up to 800 kV.
• 3EQ silicone rubber surge arresters (composite hollow core): silicone housing molded onto a fiberglass-reinforced hollow core for exceptional mechanical stability; special flange seals to prevent moisture ingress and partial discharges; directional pressure relief devices for safe arc escape; ideal for seismic zones, high-wind areas and support-insulator applications; voltage capability up to 800 kV.
• 3EP porcelain surge arresters: porcelain housing with FRP cage for robust mechanical strength; excellent sealing system and directional pressure relief devices; designed for heavy seismic or high-wind environments and applications requiring very robust support functions; voltage capability up to 800 kV.

Technical highlights and benefits
Siemens Energy designs combine high voltage capacity, mechanical strength and advanced material properties to deliver solutions for demanding high-voltage applications. Product variants (3EL, 3EQ, 3EP) enable selection according to installation needs (station vs line), environmental conditions (coastal, desert, polluted air) and mechanical demands (seismic, wind).

Comparison (selected features)
Feature | 3EL silicone Cage Design™ | 3EQ composite hollow core | 3EP porcelain design
Maximum voltage | Up to 800 kV | Up to 800 kV | Up to 800 kV
Mechanical strength | High, via FRP rod cage | Very high, via FRP hollow core | High, via porcelain housing
Housing material | Silicone rubber (hydrophobic, UV-resistant) | Silicone rubber + FRP hollow core | Porcelain
Overload safety | Arc escapes soft silicone housing | Directional pressure relief devices | Directional pressure relief devices
Maintenance | Maintenance-free due to silicone properties | Long-term reliable operation | Robust in harsh environments
Application flexibility | Station or line arresters | Station arresters in seismic/high-wind zones | Station arresters in seismic/high-wind zones
Weight | Lightweight for easy transport and installation | Moderate | Heavier but highly durable

Applications

• Transmission and distribution substations: protecting infrastructure from transient overvoltages
• Power transformers and reactors: ensuring reliable operation and longevity
• Switchgear and control equipment: safeguarding against electrical disturbances
• Overhead and underground transmission lines: maintaining uninterrupted power flow
• Sites prone to lightning, seismic activity or extreme weather: providing robust protection in challenging environments

Why choose Siemens Energy high-voltage surge arresters

• Proven reliability from decades of field experience
• Advanced materials (silicone rubber, composite materials, porcelain) for enhanced durability and performance
• Safety-first designs (directional pressure relief, arc management) to minimize risk during overloads
• Wide voltage range with solutions up to 1,200 kV for ultra-high-voltage applications
• Customizable designs to meet project- and environment-specific requirements

Caractéristiques / spécifications techniques

• Voltage capability: product family solutions for applications from medium voltage up to ultra-high voltage; portfolio includes solutions rated up to 1,200 kV (portfolio level) and specific designs rated up to 800 kV.
• Housing materials: silicone rubber (hydrophobic, UV-resistant, fire-retardant, self-extinguishing) and high-quality porcelain options.
• Mechanical design: FRP rod cage (3EL), FRP hollow core (3EQ) or porcelain housing (3EP) to meet different mechanical strength requirements.
• Sealing and moisture protection: moisture-tight silicone molding and special flange seals to prevent ingress and partial discharges.
• Overload and safety features: directional pressure relief devices (3EQ, 3EP) and arc-safe silicone housing (3EL) to allow safe arc discharge without internal part ejection.
• Environmental suitability: excellent pollution layer performance for coastal, desert and highly polluted areas; superior sealing for moisture and contamination resistance.
• Typical applications: transformers, circuit breakers, generators, motors, capacitors, bushings, switchgear, traction vehicles, transmission lines and substations.
• Maintenance: silicone-based designs offer maintenance-free operation due to material properties; porcelain designs provide robust long-term performance in harsh environments.