Surge Protection of cable connected transformer 1

[prc]

A 220 MVA generator transformer is connected to GIS by 150 meters of single core 220 kV cable.Cable is connected to transformer through oil filled cable box.There is a lightning arrester on the incoming side of GIS which is connected to overhead transmission line. Any further surge protection is required for the GSU? Any check for feroresonance is required?

 

[odlanor]

you are including Cable at the zone of Lightning Arrester of GIS. I would install LA at Cable-GIS junction and secondary (HV) GSU terminals.
there is a risk of ferroressonance if you energize unload stepup transformer from GIS without generator.

Cahier technique n° 190 -Ferroresonance fig. 10 Schneider

about GIS ,you must remember Very Fast Transients during disconnecting switching maneuver

 

[prc]

Thank you odlanor!