The electric power industry has been using Sulfur Hexafluoride (SF6) gas as a dielectric and insulating material for many years. Its popularity is mainly due to its unique physical and electrical properties including:

1) Dielectric strength twice that of air.

2) Nontoxic, nonflammable and noncorrosive.

3) Chemically stable with high breakdown strength. SF6 molecules provide excellent arc extinction during electrical operations which minimizes contact wear and maintenance.

4) Excellent thermal conductivity. High heat transfer permits lower operating temperatures.

5) Readily available in many commercial locations.

For distribution voltage switchgear, SF6 provides these important advantages:

1) Size reduction

2) Weight reduction

3) Reliable operation

4) Ease of installation

5) Ease of handling

6) Ease and reduction of maintenance Common Applications Electrical uses include high voltage circuit breakers, high voltage transformers, distribution voltage switchgear, gas insulated power substations, gas insulated transmission lines, radar equipment, linear particle accelerators and generators. Approximately 80% of the annual consumption of SF6 is used for gas insulated substation (GlS) equipment and medium voltage switchgear including circuit breakers and load break switches. Of the 80%, medium voltage switchgear accounts for approximately 10%. In both electrical applications, the equipment is designed to contain the gas in sealed pressure systems which are assembled, filled and tested in a controlled environment.