IEEE UltraSIL Polymer-Housed VariSTAR Station-Class Surge Arresters


Improve Your System Reliability with Up to 15% Increased Margin of Overvoltage Protection

Eaton's Cooper Power Systems has set a new standard of excellence in UltraSIL™ polymer-housed, station-class surge arresters. Improved energy handling capability, increased creep distance, and customization availability provide superior equipment protection in a lightweight polymer arrester.

Arrester Voltage Ratings (kV) 3-240
Rated Discharge Energy (kJ/kV of MCOV) Single Impulse Rating
US (3-108 kV) 3.9
UH (3-108 kV); US (120-240 kV) 6.2
UX (3-108 kV); UH (120-240 kV) 10
System Frequency (Hz) 50/60
Impulse Classifying Current (kA) 10
High Current Withstand* (kA) 100


The increased creep reduces the size of the arrester needed in highly contaminated environments such as:

  • Salt fog environments, including coastal substations
  • Industrial and factory applications, including mining and steel mills
  • Renewable energy applications, including solar and wind farms
  • Road salt in colder climates

Independent laboratories have verified the superiority of 100% silicone rubber for its resistance to:

  • UV degradation
  • Contaminated environments
  • Temperature stability (+200 ºC to -70 ºC)

A high-strength composite matrix encapsulates the arrester’s internal components and provides structural strength. The moisture impervious design features four discreet sealing systems:

  • Glass collar disk
  • Composite wrap
  • RTV bonded Interface
  • Silicone rubber housing UI, US