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HV/MV Equipment
Gas-Insulated Substations up to 420 kV

Home > HV/MV Equipment > Gas-Insulated Substations > GIS

Gas-Insulated Substations up to 420 kV

GE's T155 GIS is a field-proven solution with high availability that meets the challenges of networks up to 420 kV for power generation, transmission, distribution, tertiary and heavy industry applications.

The T155 is compact and accessible, with a bay footprint 40% below the market average. Complete bays are assembled, wired, tested and shipped enabling shorter site works.

In addition, the T155 is environmentally friendly and features one of the lowest gas weights on the market along with an advanced SF6 sealing system. Full digital monitoring control and protection capabilities enable the T155 to be readily integrated into the smart grid.

GE Advantage
Learn about GE's advantages in gas insulated substation technology

Customer Benefits

Customer Benefits


Environment friendliness

  • Low gas weight on the market
  • First-in-class SF6 sealing system

High availability

  • Best experience and reliability data
  • Current transformers outside SF6
  • Pure-spring circuit breaker drives
  • State-of-the-art maintenance isolating device: major repair and HV tests with no more than 1 bay down
  • Outstanding accessibility: drives and accessories at easy reach


Low costs of land and civil works

  • Most compact GIS with single-phase enclosures only: bay footprint 40% below market average

Shortest site works

  • Complete bays assembled,wired, tested and shipped (420 kV)

Smart grid features

  • Full-digital monitoring, control and protection


GIS Type T155 420 kV
Reference electrotechnical standards IEC/IEEE
Rated voltage 362-420 kV
Withstand voltages
 Short-duration power-frequency, phase-to-earth/across open switching device 650/815 kV
Switching impulse, phase-to-earth / across isolating distance 1050/900(+345) kVp
Lightning impulse, phase-to-earth / across open switching device 1425/1425(+240) kVp
Frequency 50/60 Hz
Continuous current up to 5000 A
Short-time withstand current 63 kA
Peak withstand current 170 kAp
Duration of short-circuit 3s
Installation indoor/outdoor
Ambient temperature range down to -25/up to +55 °C
First-pole-to-clear factor 1.3 - 1.5
Short-circuit breaking current 63 kA
Short-circuit making current 170 kAp
Operating sequence O-0.3s-CO-3 min-CO/CO-15s-CO
Drive type Pure-spring
Breaking time 2 cycles
Closing time <115 ms
Mechanical endurance M2 class
Capacitive switching C2 class
Capacitive current switching 0.5 A
Bus-transfer current switching capability 1600 A / 20 V
Mechanical endurance M2 class
Making current capability 170 kAp
Switching capability-electromagnetic coupling 160 A / 10 kV
Switching capability-electrostatic coupling 18 A / 20 kV
Mechanical endurance M1 class