System Features and Benefits

Mitsubishi Electric consistently delivers a competitive size reduction. This is accomplished via an aggressive space savings that is consistent across all customer projects. The design concept incorporates a compact PLC based LCC (local control cabinet) which is configurable to any customer specification. The LCC, including all breaker controls and switch interlocks, is positioned in close proximity to the Gas Circuit Breaker (GCB). As a result, this also reduces wiring work, which leads to space and cost savings. It also improves performance and reliability.

  • Compact modular design
  • 1st time cost savings per comparible level of performance per physical footprint
  • Able to ship fully assembled GIS unit
  • Ability to fit into more situational applications
  • Wiring, metals, structure all more compact
  • Less overall complexity

...Sometimes size matters...



GIS SF6 usage is reduced as a byproduct of Mitsubishi Electric’s contemporary design, as illustrated in figure 3. Leakage is rated at a maximum of 0.1% per year, but is observed to be lower thorough continuous monitoring. This is a continuation of design whereas the gas chambers are designed in tapered and other space saving geometries. The interrupter and switch mechanisms remain simplistic and efficient. Smaller volume corresponds to higher pressure at about +10 PSI. Mitsubishi Electric’s guaranteed leak rate is 1/5 of the IEEE standard. Flanges and bolted connections are all differentiated by Mitsubishi Electric’s prosperity sealing systems which allows Mitsubishi Electric SSD to provide a 30 year leak rate guarantee.



  • Lowered SF6 gas usage within more tightly constructed switchgear chambers.
  • Ability to consider Mitsubishi Electric SSD for challenging environments.
  • Substation engineering flexibility for densely populated areas.

  • Installation into smaller physical footprints.

  • Lower shipping costs.
  • Decreased Assembly time


SSD’s GIS design ensures that all gas pressure gauges are located in convenient locations and are visible from ground level.

SSD has also designed a robust viewport camera system which allows for viewports to be checked at remote positions.

4” Switch View Ports


Mitsubishi Electric has been known for single break, pure puffer interrupters for over 50 years. While other mechanisms can be implemented, this is at the heart of long reliability and long life for our GIS equipment.

50,000 operations

Simple puffer interrupters are a large part of the reason that the GIS is rated at 50,000 operations and lubrication for life;



Advantages of BMJ4 Spring Operating Mechanism:

  • Compact Design with dual-coaxial spring which increases energy density and minimizes the volume.
  • Simplistic structure with minimal moving parts.
  • Stable driving force through life time of CB, free from oil and air leakage
  • Never needs replacement. Designed to last life of GIS


Advantages of BM-2 Spring Operating Mechanism”

  • Tested to over 50,000 operations
  • Over 18,000 in operation with a flawless operational history
  • Stable operation force is obtained regardless of the variance in ambient temperature
  • Lubricated for life
  • Never needs replacement. Designed to last life of GIS

DS/ES Motor Operating Mechanism


All maintenance and switching (DS/ES) operations are performed via a single drive motor and flexible linkage cable. Motor, spur gears, pulley with Bowden cable, auxiliary contacts, spur gear, Bowden cable, pulley and motor are all in one assembly.

There is a clutch assembly designed on each switch, but a single access point for all switching operations.


Mitsubishi Electric SSD extends our compact design with respect to using Mitsubishi’s proprietary cable sealing enclosure which terminates all phase cable connections for both HPFF and XLPE type cables within a sealed GIS side of the enclosure and extends them out of the GIS domain via cable side termination. As with the remainder of the GIS installation, this allows for a 30-year leak rate guarantee

Each Mitsubishi Electric SSD GIS has self-contained gas monitoring systems located on each zone of each phase of the GIS. Customers can be assured in densely populated or otherwise critical locations that system monitoring eases evacuation, filling, inspection and monitoring, all while assuring the optimal safety and performance of the system. SSD has characterized the design of fault diagnosis and monitoring by using the minimum system elements to provide the most system information. This simplicity minimizes false alarms, unnecessary complexity and human error. Lastly, the overall design of the GIS also uses the fewest seal points in combination with low static pressure and potential leak paths to greatly increase overall reliability.