|Q:||Will there be an industry-accepted/defined common gas?|
|A:||Currently, there is no directive or industry initiative to define a single, alternative gas for SF6.|
|Q:||Why don’t all the manufacturers standardize on a single non-SF6 solution?|
|A:||SF6 is the most common solution for interruption and switching, and has been for decades. The relatively recent focus on environmental performance compels the industry to research and develop alternatives. Manufacturers are pursuing multiple solutions in order to reach a new balance between technical and environmental performance. Some of the more important factors under consideration:|
Manufacturers pursuing multiple solutions will expose the strengths and weaknesses of each technology such that end users will be the beneficiaries of a technology (technologies) that provide both the technical and environmental performance demanded by society. For more information on this question, please see the Coalition’s white paper on Alternative Insulation Technologies.
|Q:||Can the SF6 in an existing gas insulated switchgear be replaced with a non-SF6 alternative?|
|A:||Previously manufactured SF6 switchgear was not designed to work with replacement insulations. There are a number of reasons for this; some include:|
|Q:||Can the SF6 in an existing gas insulated circuit breaker be replaced with a non-SF6 alternative?|
|A:||Previously manufactured SF6 circuit breakers were not designed to work with replacement insulations. There are a number of reasons for this; some include:|
|Q:||In the U.S. are there regulations and reporting requirements for gas alternatives?|
|A:||There is no specific reporting regulations for vacuum GIE. However, there are regulations in some states that address reporting requirements for greenhouse gases (including SF6 alternatives). California is an example of this.|
Each of the 3M™ Novec™ Insulating Gases are subject to a U.S. EPA Significant New Use Rule (SNUR). Please see product SDS for further information; they are available at www.3M.com/SDS.
In addition, O2 (oxygen) also has a specific OSHA safety standard that must be reviewed and adhered to, although it does not specifically address its use in GIE. The OSHA regulation is 1910.104 – Oxygen.
As the industry advances with the research and application of alternative arc quenching and insulation materials, industry regulators will advise on reporting and environmental health and safety regulations, policies, and processes that will apply.
|Q:||Do any standards for gas insulated equipment contain leak limits?|
|A:||Yes, see the table below for a non-exhaustive list.|
|Product Type||Voltage Class||Standard||Clause||Applicability||Leak Rate|
|Gas Insulated Substations||>52 kV||IEEE C37.122-2021||6.15||SF6||0.1%/year (confirmed by type testing)|
0.5%/year (confirmed by routine testing)
|AC High-Voltage Circuit Breakers||>1 kV||IEEE C37.04-2018||7.11||Closed Pressure Systems—Any Insulating Gas||Maximum leak rate <1%/year.|
Alternate preferred leak rates are 0.5% and 0.1%/year.
|Metal-Enclosed Switchgear||1 kV –|
|IEEE C37.20.9-2019||6.13||Refillable Compartments—Any Insulating Gas||0.5%/year|
|Sealed Compartments—Any Insulating Gas||0.1%/year|
|Vertical Sections of Gas-Filled Compartments—Any Insulating Gas||0.5%/year|
|Metal-Enclosed Switchgear||>52 kV||IEC 62271:2021||6.16.3||IEC 62271-1 Clause 6.16.3 Is Applicable Except as Noted:|
|Any Single Compartment to Atmosphere and Between Compartments—Any Insulating Gas||≤0.5%/year|
|Any Single Compartment to Atmosphere and Between Compartments—SF6, SF6 Mixtures, and Other Gas Mixtures with GWP >1000||≤0.1%/year|
|Any Single Compartment to Atmosphere and Between Compartments—Gas Mixtures with GWP ≤1000||≤0.5%/year|
|Any Single Compartment to Atmosphere and Between Compartments, for Containing Less than 1 kg of Gas—SF6, SF6 Mixtures, and Other Gas Mixtures with GWP >1000||≤0.2%/year|
|High Voltage Switchgear—Alternating-Current Circuit Breakers||>1 kV||IEC 62271-100:2021||6.16|
|High Voltage Switchgear—Alternating Current Disconnectors and Earthing Switches||>1 kV||IEC 62271-102:2018||6.16|
|High Voltage Switchgear—Alternating Current Switches||1 kV –|
|High Voltage Switchgear—Common Specifications||As applic.||IEC 62271-1:2017||6.17||Controlled Pressure Systems—Insulating Gases Except Ambient Air, SF6, and SF6 Mixtures||Specified by the number of replenishments per day or by the pressure drop per day.|
|As applic.||Closed Pressure Systems—Insulating Gases—SF6 and SF6 Mixtures||≤0.5%/year|
|As applic.||Closed Pressure Systems—Insulating Gases Except Ambient Air, SF6, and SF6 Mixtures||≤1%/year|
|As applic.||Sealed Pressure Systems—Insulating Gases Except Ambient Air||Specified by the expected operating duration. Shall be designed in a way to ensure that the minimum functional pressure (density) shall not be attained before the expected end of life. The manufacturer shall specify a permissible leakage rate.|
|High Voltage Switchgear—Alternating Current Switch-Fuse Combinations||1 kV –|
|Subsurface, Vault, and Pad-Mounted Load-Interrupter Switchgear and Fused Load-Interrupter Switchgear for Alternating-Current Systems Up to 38 kV||≤38 kV||IEEE C37.74-2014||7.4|
|Pad-Mounted Dry Vault, Submersible, and Overhead Fault Interrupters for Alternating-Current Systems||≤38 kV||IEEE C37.62-2020||6.16||Controlled Pressure Systems—Any Insulating Gases||Specified by the number of replenishments per day or by the pressure drop per day.|
|Closed Pressure Systems—Insulating Gases—SF6 and SF6 Mixtures||≤0.5% or <1.0%/year|
|Closed Pressure Systems—Insulating Gases Except SF6 and SF6 Mixtures||≤0.5% or 1% or 3%/year|
|Sealed Pressure Systems—Any Insulating Gases||The tightness of sealed pressure systems is specified by their expected operating life.|
The expected operating life with regard to leakage performance shall be specified by the manufacturer.
|High Voltage Switchgear—Automatic Circuit Reclosers for Alternating-Current Systems||≤38 kV||IEEE C37.60-2018|