3EK silicone rubber surge arresters with Cage Design™

Siemens Cage Design™ 3EK distribution class surge arresters offer superior protection against overvoltages in medium-voltage systems.

Siemens 3EK Cage Design™ surge arresters are ideally suited for the reliable protection of:

• Transformers
• Circuit breakers
• Medium-voltage switchgear / panels
• Distribution lines

The metal oxide varistors (MOV) are enclosed by a cage made of fiber-reinforced plastic (FRP) rods, providing a rigid, reinforced structure ensuring high mechanical strength.

Reliability is guaranteed by the direct molding of the silicone rubber onto the MOV blocks and the FRP rods. This ensures the total embedding of all components free of inclusions and gaps, thus providing an excellent sealing system against any partial discharges or moisture ingress.

In the extremely rare event of the MOV being overloaded, arcing cannot result in a buildup of critical internal pressure, since the MOV are not enclosed in a sealed mechanical shell. The arc can escape directly through the soft silicone housing, leaving the mechanical support structure of the enclosure unharmed. The ejection of internal parts that could damage other equipment nearby is prevented almost completely. Siemens’ innovative Cage Design™ ensures outstanding performance in safety issues.

Silicone rubber is highly hydrophobic and maintains its ability to repel water and any deposits of pollution throughout its entire service life. This results in high tracking and erosion resistance. The silicone rubber housing is self-extinguishing and flame-retardant. These advantages provide maintenance-free and reliable service life for 3EK surge arresters.

Siemens offers two product lines for the application in distribution networks, which differentiate in the mechanical strength:

• 3EK4 – for rated voltages up to 36 kV, high mechanical performance.
• 3EK7 – for rated voltages up to 60 kV, very high mechanical performance.

The proven 3EK7 is also available in a version for indoor application, which is a Cage Design™ surge arrester offering the same benefits as the version for outdoor application.