IEC UltraSIL Housed VariSTAR Type U3 Surge Arrester for Systems through 275 kV 10 kA; Line Discharge Class 3


UltraSIL Polymer-Housed VariSTAR U3 Surge Arresters offer the latest in metal oxide varistor (MOV) technology for the economical protection of voltage class power and substation equipment. These arresters are gapless and are constructed of a single series column of 63 mm diameter MOV disks.

The arrester is designed and tested to the requirements of the International Electrotechnical Commission Standard IEC 60099-4, and is available in ratings suitable for the transient overvoltage protection of electrical equipment on systems through 275 kV.

The UltraSIL Polymer-Housed U3 Surge Arrester incorporates the industry recognized superior polymeric material – Silicone Rubber. The advantages of polymer-housed arresters – reduced size and weight and enhanced safety – have been refined in this next generation of surge arresters: the UltraSIL Polymer-Housed U3 Surge Arrester from Cooper Power Systems.

Catalog Number U3AA003002A0845AAA
Arrester Voltage Ratings, Ur 3-240 kV
Rated Discharge Energy: Single Impulse 6.2 kJ/kV of Uc; 5.1 kJ/kV of Ur
Rated Discharge Energy: Double Impulse 9 kJ/kV of Uc; 7.5 kJ/kV of Ur
System Frequency (Hz) 50/60
Nominal Discharge Current (kA) 10
High Current Withstand, Short Duration Withstand 4/10 μs (kA) 100
Short-Circuit/Pressure Relief Rating (kA rms sym.) 65
Ambient Temperature (°C) -40 to +40


  • The UltraSIL silicone rubber housing was selected for its superior insulation performance as compared to other polymeric housing materials. Long term environmental testing has verified the lifetime performance advantage that silicone rubber provides.
  • Independent laboratory tests have verified the superior water repellent behavior of silicone rubber, which is responsible for the lower external power losses, higher resistance to UV degradation and surface tracking, superior performance in contaminated environments, and other important insulating properties. Also, UltraSIL silicone rubber has been proven not to support biological growth and is non-flammable.
  • The basic silicone rubber-housed arrester can be customized with a variety of terminal and mounting options which allow users to select the features that meet their application needs. Customers who require longer creepage housings can easily select a different housing option through the catalog numbering system.

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