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Gas-insulated switchgear ELK-4 up to 800 kV

Extra high-voltage GIS

The gas-insulated switchgear ELK-4 is used for long range power transmission at extra high voltages (EHV) of up to 800 kV. ELK-4 offers optimized, compact and easily accessible layouts for the common one-and-a-half-breaker and two-breaker circuit schemes. High performance circuit breakers with pre-insertion resistors provide reliable switching and protection. Hitachi Energy delivered the first generation ELK-4 GIS to South Africa for ESKOM’s 765 kV grid in 1987. The substation was one of the first ever commissioned 800 kV GIS worldwide and continues to provide excellent service.


  • Long range power transmission
  • Very large power plants

Why Hitachi Energy?

  • Proven GIS technology over five decades
  • Worldwide footprint and experience
  • Comprehensive experience and excellent performance in EHV and ultra high voltage GIS technology
  • Excellent design, test and service capabilities

Brief performance data

Rated voltage [kV] 800
Rated frequency [Hz] 50
Rated short-duration power-frequency withstand voltage (1 min) [kV] 960
Rated lightning impulse withstand voltage (1.2/50 µs) [kV] 2,100
Rated switching impulse withstand voltage (250 / 2500 µs) [kV] 1,550
Rated normal current – busbar / feeder [A] 6,300/5,000
Rated short circuit-breaking current [kA] 63
Rated short-time withstand current (up to 3 s) [kA] 63
Rated peak withstand current [kA] 171
Bay width [mm] 9,420
Ambient temperature range [°C] -30 … +40
Installation indoor / outdoor
power plant engineer for substation

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