Gas insulated substation surge

[Mlmlzx]

Dear sirs,

What could be the reason for the need is surge arrester in a gas insulated substation? Is it necessary on the transformer bay?

Regards

 

[cranky108]

Maybe switching surges?

 

[Gr8blu]

The purpose of a surge arrester is to limit damage resulting from transient overvoltage. Usually they are applied to power transformers and (some) switchgear assemblies. For GIS (gas insulated switchgear), a special high-gradient metal-oxide block is used (often multiples, connected in series, with an SF6 or similar gas). Likely causes of high transients include: lightning strikes, switching (particularly high-speed and/or high-frequency operations), and capacitor failures.

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[Kiribanda]

If the GIS station is connected to an overhead line then it is obvious that due to change in surge impedance,
a SA has to be installed at the junction.