Switchgear |


in the high-voltage range in particular? Not any longer. Thanks to patented vacuum switching technology, Siemens Energy’s F-gas-free Blue products are available on the market for voltage levels up to 170 kV, as already noted, and they’re just as compact as SF6


-insulated gas-


Innovative centrepiece of the 145 kV 8VN1 Blue switchgear: the vacuum interrupter technology


payments in the future and, in the worst case, financial penalties.


Various manufacturers are now trying to provide ways to address the environmental and economic risks associated with SF6


. Some are


. But these alternative F-gases are still non-climate-friendly, and even at a low level of leakage (0.5%), nature will still need several decades to absorb a fluoronitrile mix. Others, including Siemens Energy, are focusing their development efforts on sustainable and future-proof innovations, in other words on products that do without F-gases entirely. They use “processed” air, ie, clean air, instead. Clean air contains no harmful byproducts whatsoever. It’s a pure mixture of nitrogen and oxygen. Its greenhouse gas potential is zero, and there’s no risk to the environment. And purified air is not only entirely harmless but it’s available in abundance. So why should we use fluorinated gases if it’s better not to? In the short term, an F-gas mixture may look like an easy compromise. But are there really no alternatives to this solution


replacing this highly climate-damaging gas with a mixture of gases that contains less climate damaging F-gases, such as fluoronitriles, instead of SF6


insulated switchgear (GIS), and sometimes even smaller if digital products such as flexible low- power instrument transformers (LPIT) are used. A further benefit is the combination of low lifecycle costs and good switching properties: whereas gas mixtures degrade over time, vacuum switching technology enables a large number of switching processes with no wear to the contacts, making it almost maintenance- free. Californian utility company Pacific Gas and Electric (PG&E) aims to abandon SF6


entirely.


In a comparative investigation, the magazine Transmission & Distribution World wrote: “Dry air/vacuum currently is the lowest-cost life-cycle option.”1


in switching technology, and discovered that “The use of gas mixtures involving F-gases containing carbon (C5-PFK, C4-PFN) can compromise the service life of gas-insulated systems: (…) clean air is a gas mixture with excellent long-term stability and no toxicological restrictions.”2


Northern Europe shows how it’s done


BKK Nett, Norway’s second-largest power network operator, also aims to eliminate greenhouse gases from its transformer substations. It has put its first F-gas-free GIS from Siemens Energy into operation.


The key factor is that the Koengen 145 kV transformer substation in Bergen in the clean air version with digital low-power instrument transformers is of a similar size to a substation


Comparison: clean air vs. other insulation media SF6


Gas / GWP(100)* SF6 / 25 200 Resulting GWP(100)* ▼ 25 200*** Lifetime Toxicity ****


F-gas reporting & restrictions


▼ 3200 years


▼ Toxic byproducts, hazardous when inhaled, causes skin & eye irritation


▼ Yes Temperature range ▼ -30°C Availability


On behalf of the German government, Ecofys, a member of the Navigant Group, and ETH Zürich Technical University studied alternatives to SF6


Fingrid opts for clean-air GIS at Virkkala


Another recent adopter of Siemens Energy’s clean-air based SF6


-free gas-


insulated-switchgear is Fingrid, Finland’s transmission system operator, which has placed a contract for ten bays of type 8VN1 GIS equipment (pictured below) from Siemens Energy’s Blue portfolio – the first such installation in Finland. Fingrid decided to modernise the 110 kV switchgear at its Virkkala substation so that it operates without any climate- harming gases. Commissioning is scheduled for summer 2022.


employing SF6


-insulated GIS with conventional instrument transformers.


Jens Skår, Division Manager at BKK Nett, comments: “Someone has to take the first step. We didn’t want to make a decision today that would embarrass us two years down the line.” BKK is already benefiting from easier maintenance and the fact it no longer needs to record and report the SF6


in its transformer substations.


An advantage for more northerly locations where these systems are used: the new F-gas- free products can function in temperatures down to minus 60°C.


Fluoronitrile-mix (CF3)2


+ CO2 / 1 + O2


CFCN / 2750** / 0


▼ > 500*** depending on application and multiple gas mix composition


▼ 30 years


▼ Toxic byproducts with every switching


▼ Yes ▼ Typically -25°C ▼ Established sources ▼ Single source ** New registered greenhouse gas within the IPCC (Intergovernmental Panel on Climate Change) report * Global warming potential (100 year horizon) in CO2


*** Not in line with zero emission and climate neutrality targets of societies and most of the users specifying GWP <1 **** Not in line with toxic free environmental strategy without PFAS substances for good health and well being as well as clean water


Clean air N2


(79.5% / 20.5%) / 0 + O2 ▲ 0 ▲


▲ Non-toxic ▲ Non-hazardous


▲ No ▲ -60°C


▲ Multiple sources, available in every country


-equivalent based on latest IPCC AR6 publication


And with more than 400 installations around the world and six million hours of commercial high-voltage operation, Siemens Energy’s Blue technology, compared with SF6


-insulated


switchgear, has already saved the equivalent of two million metric tons of CO2


. To absorb that


amount of carbon would require about 160 million trees.


1


Transmission & Distribution World (2019), “PG&E phases out SF6


greenhouse gas”, https://www.


tdworld.com/substations/article/20972256/pge- phases-out-sf6-greenhouse-gas


Ecofys (part of the Navigant Group) and Eidgenössische Technische Hochschule Zürich (2018): Konzept zur SF6-freien Übertragung und Verteilung elektrischer Energie. Abschlussbericht. [Concept for SF6-free transmission and distribution of electrical energy (Final Report)], commissioned by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.


2 28 | October 2021 | www.modernpowersystems.com


Performance


Impact on environment, health & safety


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