HV Three Position Switches

EmpireWind

Member
Location
Virginia
Occupation
Electrical Engineer
Anyone have experience with three position switches at HV and EHV level? How are safety rules written to provide isolation and grounding?
Is it preferable to have a separate disconnect switch and a separate grounding/earth switch?
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
You’ll have to be a little more descriptive about what your asking.
three position switches for a substation doesn’t ring a bell with me.
Got a picture?
 

EmpireWind

Member
Location
Virginia
Occupation
Electrical Engineer
It is a part of a specification I am reviewing for a GIS. The vendor is proposing a 3-position switch, which combines a disconnect with grounding switch.
I looked at IEEE C37.122 standard and C37.122.1 guide and both are silent on that. I have not seen it used in the US in switchyards.
The standard guide shows a one line with separate ground and separate disconnect but the standard does not explicitly spell that out.
The vendor is contending that the three way switch gives the same functionality.
 
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