To some degree

SF

6

alternative techniques play an important role in the development and application of GIL.Therefore

starting with the technique development of SF

6

alternatives

we review the GIL history and the application of SF

6

alternative technique in GIL.Combined with the current progresses of SF

6

alternatives and GIL

some prospective studies on GIL are also discussed.Along with the breakthrough of SF

6

/N

2

gas mixture technique

the 2nd generation GIL achieves successfully commercial applications

and SF

6

alternatives have been actively explored.Alstom and ABB provided C4 FK mixtures and C5 FK mixtures

respectively

to replace SF

6

causing widespread concerns.Moreover

Alstom carried out temperature rise test of C4 FK mixtures on a 420 k V GIL prototype

but the temperature rises are in the range of 10%

1

5% higher than that of SF

6

.It is shown that the 3rd generation GIL is still in the laboratory research stage.As the development of SF

6

alternative technique and the improvements in GIL construction

the 3rd generation GIL

i.e.environmental friendly gases as dielectric gases

will possibly open a new age.