Vacuum or SF6 at 11 kV, 22 kV and 33 kV: The Decision After the F-Gas Phase-Down

For new medium voltage switchgear at 11 kV, 22 kV and 33 kV, vacuum is the better choice, and the EU F-gas phase-down has turned that engineering preference into the direction of the whole market. Regulation (EU) 2024/573 prohibits putting into operation new switchgear that uses fluorinated gases for insulation or breaking up to 24 kV from 1 January 2026, and from 24 kV to 52 kV from 1 January 2030. Vacuum circuit breakers (VCBs) already cover every rating an Indian plant needs at these voltages, with no gas to monitor, top up or lose. That is why New India Electricals Ltd (NIEL) treats vacuum as the default for every new MV board from 11 kV to 36 kV.

TL;DR

• At 11 kV, 22 kV and 33 kV, a vacuum circuit breaker interrupts the arc inside a sealed interrupter, while an SF6 breaker relies on sulphur hexafluoride gas. Vacuum removes the gas, and with it the leak checks, refilling and end-of-life gas recovery.

• The EU has banned new F-gas switchgear from being put into operation at medium voltage: up to 24 kV from 1 January 2026, and from 24 kV to 52 kV from 1 January 2030, under Article 13(9) of Regulation (EU) 2024/573.

• SF6 carries a global warming potential of 24,300 over 100 years, according to Annex I of the same regulation. The US EPA calls it the most potent greenhouse gas known, with an atmospheric lifetime above 1,000 years.

• Vacuum is proven at 33 kV. ABB’s VD4 vacuum breaker covers 36 kV and 40.5 kV at 16 kA to 40 kA and 630 A to 3,150 A, and ABB states its interrupters are maintenance-free during their service life.

• The EU rule does not apply to an Indian plant, but the supply side is moving anyway. SINTEF reports that most medium voltage manufacturers now offer SF6-free products up to 24 kV.

• “Vacuum breaker” is not the same as “SF6-free panel”. Check the insulating medium as well as the breaking medium, because some compact switchgear pairs vacuum interrupters with SF6 insulation.

What is the real difference between a VCB and an SF6 breaker at 11 kV to 33 kV?

A vacuum circuit breaker (VCB) interrupts current by separating contacts inside a sealed vacuum interrupter, while an SF6 circuit breaker quenches the arc in sulphur hexafluoride gas held under pressure. At 11 kV to 33 kV both can meet the ratings, so the decision turns on what each technology asks of the plant over its service life.

The US EPA’s page on SF6 basics explains why the gas became popular: its dielectric properties make it effective for insulation, current interruption and arc quenching. The same page explains the problem. SF6 can escape during manufacturing, installation, maintenance and decommissioning, and significant leaks can occur from ageing equipment.

Vacuum removes that failure path. NIEL’s position, set out in its engineering knowledge base, is that vacuum is the default for MV switchgear up to 36 kV because there is no gas to monitor, top up or leak, which matters most on dusty, coastal, high-altitude and remote sites where specialist maintenance skill is limited.

What exactly does the EU F-gas regulation ban, and from when?

The EU F-gas regulation bans the putting into operation of new electrical switchgear that uses fluorinated greenhouse gases, including SF6, as its insulating or breaking medium, on a voltage-based timetable. Regulation (EU) 2024/573 of 7 February 2024 sets the dates in Article 13(9).

The medium voltage rule is strict. The derogation in Article 13(11) allows F-gas switchgear with a global warming potential below 1,000 only when a procurement receives no bids, or bids from only one manufacturer, for equipment free of fluorinated gases in the first two years after each date, and only when no such bids arrive after that. SF6, at 24,300, sits outside even that derogation: Article 13(12) allows a gas of 1,000 or more only when no bid below 1,000 is received.

The regulation also reaches equipment already installed. Existing switchgear may still be repaired and serviced under Article 13(18), but from 1 January 2035 the use of SF6 for maintenance or servicing of electrical switchgear in the EU is prohibited unless the SF6 is reclaimed or recycled. Switchgear ordered before 11 March 2024 is exempt from the new-installation ban under Article 13(14).

The EU is not alone. The US EPA’s summary of state SF6 regulations records that California finalised a phase-out of SF6 in gas-insulated equipment starting in 2025, and that New York’s Part 495 rule, finalised in 2024, begins a voltage-based phase-out in 2027.

Why does SF6 matter so much as a greenhouse gas?

SF6 matters because a small leak carries a very large climate cost. Annex I of Regulation (EU) 2024/573 lists sulphur hexafluoride with a global warming potential of 24,300, meaning 1 kg released has the warming effect of 24,300 kg of CO2 over 100 years.

The US EPA describes SF6 as the most potent greenhouse gas known to date, with an atmospheric lifetime of greater than 1,000 years, and notes that it accumulates in the atmosphere essentially undegraded for many centuries. The EPA page quotes a slightly lower figure of 23,500 times CO2, while the EU regulation uses 24,300. Either figure leads to the same conclusion.

The power sector is where the gas now concentrates. The EPA attributes approximately 67% of all US SF6 emissions in 2022 to the electrical transmission and distribution sector. SINTEF Energy Research reports that Statnett, Norway’s transmission operator, attributed 72% of its direct scope 1 emissions in 2024 to SF6. For an Indian manufacturer reporting scope 1 emissions to export customers, every kilogram that leaks from an SF6 panel adds to that report, and a vacuum panel has nothing to leak.

Is vacuum proven at 33 kV, or only at 11 kV?

Vacuum is proven at 33 kV. ABB’s VD4 vacuum circuit breaker instruction manual for 36 kV and 40.5 kV (1VCD601314) covers rated short-circuit breaking currents from 16 kA to 40 kA and rated currents from 630 A to 3,150 A.

ABB’s VD4 product page lists the family up to 46 kV, 4,000 A and 63 kA, with a global installed base of more than 2 million units and 30,000 overhaul-free mechanical operations on most ratings. The 36 kV manual states that the interrupters are maintenance-free during their service life, with inspection by a trained electrician at least every 4 years and servicing of the spring mechanism after 10,000 operating cycles.

SINTEF confirms where the real limits of vacuum lie. Vacuum does not scale as easily as gas at transmission voltages, because insulation must come from distance rather than pressure. That is a challenge at 145 kV and 420 kV. At 11 kV to 33 kV, SINTEF notes that vacuum has been the standard interruption technology for decades.

Which vacuum panel fits 11 kV, 22 kV and 33 kV?

Each of the three common Indian MV levels has a vacuum panel at NIEL, and the 22 kV and 33 kV ranges use ABB vacuum breakers. NIEL is an ABB Licensed System House and assembles its MV panels in a 30,000 sq ft ABB-licensed unit.

The Power+ V indoor VCB panel covers 3.3 kV, 6.6 kV and 11 kV. The Power+ V2 22 kV VCB panel uses ABB Vmax breakers up to 31.5 kA and VD4 at 40 kA. The Power+ V3 33 kV VCB panel uses the ABB VD4 33 kV breaker.

The 33 kV panel carries independent proof. NIEL’s 36 kV rated, 33 kV indoor VCB panel has cleared CPRI and ERDA type tests between December 2024 and July 2025, including a short-circuit withstand of 31.5 kA for 1 second with a 78.75 kA peak, a temperature rise test at 1,250 A, a 170 kVp lightning impulse test and IP4X. After the short-circuit test, the VCB operated normally on the first attempt.

Does a vacuum panel change how the switchgear is operated and maintained?

A withdrawable vacuum panel simplifies both isolation and maintenance. In a walkthrough of an 11 kV lineup filmed at NIEL, the presenter explains that racking out a withdrawable VCB creates the isolating distance the IEC standard requires, so no dedicated disconnector is needed, whereas the breakers in gas-insulated switchgear are fixed type and do need disconnectors.

The Power+ V3 panel adds the features that make that withdrawable design safe to operate: a foolproof mechanical interlock that prevents racking a closed breaker, automatic metal shutters over live parts when the breaker is racked out, and racking between test and service positions with the cubicle door closed. The breaker trolley is supplied with the panel for maintenance.

Maintenance on a VCB comes down to the mechanism, not the interrupter. Following the ABB VD4 manual, a plant schedules inspection at least every 4 years and spring mechanism servicing after 10,000 operations, and the breaker never needs a gas cart, a pressure gauge log or a certified gas handler on site.

What should plants do with the SF6 switchgear they already have?

Plants should keep existing SF6 switchgear safe and leak-tight, and plan its replacement with vacuum rather than extending it with more SF6. Nothing in Indian practice requires SF6 panels to be removed, and even in the EU, Article 13(18) of Regulation (EU) 2024/573 allows parts to be installed for repair or servicing of existing switchgear.

The EPA identifies leak detection and repair, the use of recycling equipment and employee training as the cost-effective ways to reduce SF6 emissions from existing equipment. Old gear is the concern: the EPA notes that significant leaks can occur from ageing equipment.

When an SF6 board reaches the end of its life, or when a plant expands, the new sections should be vacuum. For a board where an extension would otherwise force a like-for-like SF6 addition, it is often the point to re-plan the lineup. NIEL’s guide on how to specify an 11 kV, 22 kV or 33 kV MV switchgear panel covers the busbar, interlock and type test points that decide the rest of that specification.

Does the EU rule matter for a plant in India or Africa?

The EU rule does not bind a plant in India, Zambia or Nigeria, but it shapes what the global supply chain builds. SINTEF reports that most medium voltage manufacturers now offer SF6-free products up to 24 kV and were ready for the first EU deadline in January 2026. As EU and US state demand moves to SF6-free equipment, the long-term spares and service base for MV switchgear moves with it.

Site conditions in export markets favour vacuum for the reasons NIEL already specifies it: no gas to monitor on remote sites, and no dependence on specialist gas handling skills. Altitude still needs attention. The ABB VD4 36 kV manual rates the breaker for installation up to 1,000 m above sea level, so a Copperbelt or Kenyan highland site needs the altitude correction built into the panel design. NIEL’s guidance on derating electrical equipment for African installations sets out how ambient temperature and altitude change the specification.

Where a board is bought for an EU-linked customer, or by a group with scope 1 emissions targets, specifying vacuum removes the question entirely. A panel bought in 2026 will still be in service long after the EU’s 2030 and 2035 dates.

What should a vacuum MV panel specification include?

A vacuum MV panel specification should state the breaking medium, the insulating medium and the type test evidence together, because a VCB inside an SF6-insulated enclosure is not an SF6-free panel. Use this checklist when issuing an 11 kV, 22 kV or 33 kV enquiry:

1. Breaking medium. Specify vacuum circuit breakers, and name the breaker make and model offered.

2. Insulating medium. State that the panel must not use SF6 or any other fluorinated gas for insulation, and ask for a declaration from the manufacturer.

3. Ratings. Give rated voltage (12 kV, 24 kV or 36 kV), rated current and short-circuit current with duration.

4. Type test certificates. Ask for CPRI or ERDA certificates for the exact rating purchased, since a certificate issued for another rating does not cover a different panel.

5. Site conditions. State altitude, maximum ambient temperature, humidity and pollution level, and require the corrections these need.

6. Withdrawable design. Specify withdrawable breakers with door-closed racking, automatic metal shutters and interlocks against racking a closed breaker.

7. Maintenance plan. Ask for the breaker’s inspection interval and mechanism service interval, in operations and in years.

8. Protection and communication. Specify the relay, CT and VT requirements and the communication protocol at the same time.

9. Future extension. Confirm that future sections can be added in vacuum without SF6.

   Frequently asked questions

   Is SF6 banned in India?

   No, SF6 switchgear is not banned in India under any rule reviewed for this article. The ban that exists is Regulation (EU) 2024/573, which applies to switchgear put into operation in the European Union: up to 24 kV from 1 January 2026 and from 24 kV to 52 kV from 1 January 2030. The US states of California and New York have their own phase-outs. For an Indian buyer the rule matters indirectly, because manufacturers are shifting their MV ranges to SF6-free designs and export and multinational customers increasingly specify them.

   Is a vacuum circuit breaker suitable for 33 kV?

   Yes. ABB’s VD4 vacuum circuit breaker is rated for 36 kV and 40.5 kV, with short-circuit breaking currents from 16 kA to 40 kA and rated currents from 630 A to 3,150 A. NIEL’s Power+ V3 33 kV panels use the ABB VD4 33 kV breaker, and NIEL’s 36 kV rated indoor VCB panel has passed CPRI and ERDA type tests including 31.5 kA for 1 second. Vacuum becomes harder to apply only at transmission voltages such as 145 kV and above, according to SINTEF.

   Does a vacuum circuit breaker need maintenance?

   The vacuum interrupter itself needs no maintenance during its service life, according to ABB’s VD4 36 kV instruction manual, but the operating mechanism does. The same manual calls for inspection by a trained electrician at least every 4 years under normal conditions and servicing of the spring mechanism after 10,000 operating cycles. There is no gas pressure to monitor and no gas to top up, which removes the leak checks and gas handling that SF6 equipment requires.

   What is the global warming potential of SF6?

   SF6 has a global warming potential of 24,300 over 100 years, according to Annex I of Regulation (EU) 2024/573. That means 1 kg of SF6 released has the same warming effect as 24,300 kg of CO2. The US EPA quotes 23,500 and describes SF6 as the most potent greenhouse gas known, with an atmospheric lifetime of greater than 1,000 years. Because the gas barely breaks down, every leak from switchgear keeps warming the climate for centuries, which is why regulators treat even small SF6 losses from electrical equipment seriously.

   Is a ring main unit with vacuum breakers automatically SF6-free?

   No. A ring main unit or compact panel can use vacuum interrupters for breaking and still use SF6 as the insulating gas around them. SINTEF notes that vacuum interruption has long been used in combination with SF6 insulation. The EU regulation covers switchgear that uses fluorinated gases in either the insulating or the breaking medium, so a buyer who wants an SF6-free board should specify both media and ask the manufacturer for a declaration.

   What happens to existing SF6 switchgear after the phase-down?

   Existing SF6 switchgear can stay in service. Even in the EU, Article 13(18) of Regulation (EU) 2024/573 allows repair and servicing of existing switchgear, although from 1 January 2035 SF6 used for servicing in the EU must be reclaimed or recycled. The practical plan follows the US EPA’s recommended measures: leak detection and repair, gas recycling equipment and trained staff. Keep existing SF6 panels leak-tight, recover gas properly during maintenance, and specify vacuum for every extension and replacement.
   For an 11 kV, 22 kV or 33 kV board, send NIEL your single line diagram, fault level and site conditions through our contact page, and our switchgear engineers will propose the matching vacuum panel from the medium voltage panel range.

   Specifying vacuum for your next MV board?

   NIEL is an ABB Licensed System House and assembles vacuum MV panels from 3.3 kV to 33 kV, with CPRI and ERDA type test certificates on its 36 kV rated panel. Send us your rated voltage, fault level, site altitude and any existing SF6 sections you plan to extend, and our engineers will specify a vacuum lineup to match.

   Find the vacuum panel for your voltage:

   • Medium voltage panels: the full indoor and outdoor range.

   • Power⁺ V indoor VCB, 3.3 kV to 11 kV: withdrawable vacuum breakers for 11 kV boards.

   • Power⁺ V2 indoor VCB, 22 kV: ABB Vmax and VD4 breakers.

   • Power⁺ V3 indoor VCB, 33 kV: ABB VD4 breaker, CPRI and ERDA type tested.

   • Power⁺ VO outdoor VCB, 3.3 kV to 11 kV and Power⁺ V3O outdoor VCB, 33 kV: vacuum for outdoor substations.

   Call +91 80 42434343, email support@newindiaelectricals.com, or contact our team with your enquiry.

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