Size and costs are reduced by designing a GIS with all three phases in one common
enclosure. Mitsubishi Electric’s 140SFMT uses a combined disconnect and grounding
switch with the disconnect and grounding blades joined to a common drive shaft. Automatic interlocking between these two switches ensures a high degree of operator safety.
Opening and closing operations are spring-driven. Because of permanent lubrication and
no pumps or compressors, these switch operators require little maintenance and fewer resources.