43 | September 2025 | www.industrialoutlook.in
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UEST RTICLE
1. Gas-Insulated Switchgear (GIS)
One of the most common uses of SF₆ is
in gas-insulated switchgear. In GIS sys-
tems, electrical conductors are encased
in a sealed environment filled with SF₆
gas, which acts as an insulator and arc
extinguisher. (Refer figure 2)
• Benefits:
• Compact design, reducing substation
footprint.
• High reliability and low maintenance.
• Ideal for urban and restricted spaces
like underground substations.
Fig.2 Gas Insulated Switchgear (GIS)
2. Circuit Breakers
SF₆ circuit breakers are extensively
used in power transmission systems.
They interrupt current flow during fault
conditions by extinguishing the arc
using SF₆. (Refer figure 3)
• Advantages:
• High breaking capacity.
• Fast operation.
• Low operational noise and mainte-
nance.
Fig.3 Gas Insulated Circuit Breaker
3. Gas-Insulated Lines (GIL)
GILs are used where overhead lines are
impractical, such as through tunnels or
densely populated areas. They are filled
with SF₆ and are known for their
durability and efficiency.
• Applications:
• Interconnecting substations.
• Power transmission through challeng-
ing terrains.
4.
Instrument Transformers
and
Bushings
SF₆ is also used in other power system
components such as instrument trans-
formers, bushings, and load break
switches due to its insulating properties.
2.0 ENVIRONMENTAL IMPACT OF
SF6 & EMISSION SOURCES
Contribution to SF6 is a potent green-
house gas with a high GWP, primarily
due to its efficient absorption of
infrared radiation. This characteristic
makes it a substantial contributor to
climate change, even at low atmospher-
ic concentrations i.e. approximately
10.5 parts per trillion in 2021. Studies
estimate that 1 kg of SF6 equates to
23,500 kg of CO2 in terms of climate
impact over 100-years period. Although
it constitutes a small fraction of total
greenhouse gas emissions, its long
atmospheric
lifetime
amplifies
its
long-term effect on global temperatures,
emphasizing the need for targeted
reduction strategies.
2.1 Sources of SF6 Emissions
SF6 emissions primarily originate from
its use in electrical equipment, where it
serves as an insulating and arc-quench-
ing medium. Emissions occur during
manufacturing,
installation,
mainte-
nance, and decommissioning of equip-
ment. Key sources include:
A. Leaks from equipment: Aging or
poorly
maintained
gas-insulated
systems can leak SF6 during operation.
B. Improper handling: Emissions
during the filling, recovery, or recycling
of SF6 in equipment.
C. Equipment decommissioning: Im-
proper disposal or venting of SF6 at the
end of equipment life.
D. Other applications: Smaller contri-
butions from SF6 use in magnesium
casting, semiconductor manufacturing,
and medical applications (e.g., retinal
surgery).
Global SF6 emissions were estimated at
7,140 metric tons in 2020, equivalent to
approx. 167 million metric tons of CO2.
The electrical power sector accounts for
the majority of these emissions, with
significant contributions from develop-
ing nations where electrical infrastruc-
ture is expanding.
This trend highlights the need for
continued monitoring and mitigation
efforts to reduce SF6 emissions.
2.2 Ecological and Health Implica-
tions
The ecological impact of SF6 is primar-
ily driven by its contribution to climate
change, resulting in rising sea levels,
more intense weather patterns, and
habitat destruction. While SF6 is
non-toxic, the decomposition products
from electrical arcing, such as sulfur
pentafluoride (SF5), can pose health
risks, including respiratory irritation
when released in confined spaces. These
direct and indirect effects highlight the
importance of implementing robust
management practices in engineering
applications to mitigate the adverse
effects of SF6. “
3.0 CHALLENGES IN MANAGING
SF6 EMISSIONS
The unique properties of SF6 make it
difficult to replace in many applica-
tions, posing significant challenges to
emission reduction:
1. Lack of viable alternatives: Few
gases match SF6’s dielectric strength
and stability, complicating the transi-
tion to less harmful substitutes.
2. Long atmospheric lifetime: Once
released, SF6 persists in the atmosphere
for millennia, making emission preven-
tion critical.
3. Global supply chain complexities:
SF6 is used in equipment manufactured
and deployed worldwide, requiring
coordinated international efforts to
manage emissions.
4. Cost of mitigation: Retrofitting
existing equipment or adopting new
technologies involves significant finan-
cial investment.