Disconnectors and Earthing Switches — High-Voltage Portfolio (3DN0–3DN9, 3DV Motor Drives)

Portfolio, customer service and contact technology

Siemens Energy operates a dedicated business unit for high-voltage disconnectors and earthing switches, with 123,000 units delivered to over 110 countries. The portfolio spans voltage levels from 40.5 kV up to 1200 kV, rated currents up to 5000 A, rated short-circuit currents up to 80 kA and ambient temperatures from -60 to +55 °C, type-tested to the latest international standards (IEC, ANSI, GOST). Quality is assured under ISO 9001, and long-term operational experience covers special applications such as extreme-temperature designs, test-laboratory equipment, HVDC applications and combined designs with surge arresters.

Service is delivered from one source: installation, commissioning, maintenance, training, technical support and product consulting. Disconnector poles ship pre-assembled and pre-adjusted so erection needs only standard tools, and maintenance-free components (joints and rotating units greased for life, protected against wash-out, dry-lubricated contacts) minimise lifetime effort. A production network present in more than 90 countries and a 24-h service hotline back the products, which are fully recyclable at end of life.

The Siemens Energy block/finger contact system uses no pressing springs — contact force is self-produced, and it actually increases under short-circuit conditions, giving high dynamic and thermal stability during fault currents. A graphite-silver (AgC) coating provides dry lubrication with no greasing, each contact finger bears on two contact points, and operation is maintenance-free long term.

Arc restrictors (bus-transfer contacts) are available for all Siemens Energy disconnector types, enabling the disconnector to handle the induced currents that arise during busbar transfer, where the potential difference between bus 1 and bus 2 draws an electrical arc between the contacts (load cases per IEC 62271-102 Annex B). The arc restrictors have passed type tests with more than 100 operating cycles of current making and breaking; most disconnector types offer an optional bus-transfer current capability of 1600 A.

3DN0 — Earthing switches (add-on / stand-alone)

Earthing switches guarantee absolute de-energisation of high-voltage components in a circuit or switchgear. Free-standing earthing switches are available for all voltage levels up to 550 kV, and suitable built-on earthing switches exist for every disconnector type in the Siemens Energy range — arranged laterally or integrated, depending on the position of the disconnector's main current path. Where required, all earthing switches can be designed for switching induced inductive and capacitive currents per IEC 62271-102 Class A, Class B or super Class B.

Common ratings: rated normal current up to 1000 A; rated peak withstand current up to 160/164 kA; rated short-time withstand current up to 63 kA; rated short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operating mechanism; control voltage 60/110/125/220 V DC or 220…230 V, 1~, 50/60 Hz AC (alternatively 60/110/125/220 V DC with 110/125/220 V 1~ or 220/380/415 V 3~, 50/60 Hz AC); maintenance interval 25 years. All values in accordance with IEC; other values on request.

3DN1 — Centre-break disconnector (DBF / CR series)

The centre-break is the most frequently used disconnector type worldwide. Two rotatable insulators are mounted on the switch base, and because the current path opens to the side, the phase distance is larger than with other disconnector types. This makes the centre-break highly versatile — applicable in parallel, diagonal or in-line arrangements.

Key features: cylindrical self-resilient contact fingers with AgC coating for optimal spring-free contact (dry lubrication, self-cleansing, high reliability); optional bus-transfer current capability of 1600 A; exceeds IEC and meets GOST R and GB/DL standards.

The current design has considerably reduced total weight through fewer steel parts, especially in the base frame, cutting installation effort and transport cost, while withstanding very high terminal and mechanical loads with supreme seismic capability. Corrosion-free components such as hot-dip galvanised steel parts give a particularly long service life. The 3DN1 is designed for -55 to +55 °C ambient, with high short-circuit capability and excellent ice-breaking behaviour.

Common ratings: rated normal current up to 4000 A; rated peak withstand current up to 160 kA; rated short-time withstand current up to 63 kA; short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operation; control voltage 60/110/125/220 V DC or 220…230 V, 1~, 50/60 Hz AC (alternatively 110/125/220 V 1~ or 220/380/415 V 3~, 50/60 Hz AC); maintenance 25 years. All values per IEC; other values on request.

3DN2 — Double-side break disconnector (ZBF / DR series)

The double-side break disconnector has three support insulators: the centre one sits on a rotating unit and carries the current path, while the outer insulators carry the fixed contacts. It is mainly applied in substations with limited phase distance and where vertical opening of the current path is impossible due to spatial constraints.

Key features match the centre-break contact technology: cylindrical self-resilient AgC-coated contact fingers, optional 1600 A bus-transfer capability, and compliance exceeding IEC while meeting GOST R and GB/DL standards. The unit can be customised to the substructure and is delivered pre-adjusted for easy assembly. High contact force gives excellent ice-breaking and short-circuit behaviour, and the self-interlocked end position ensures safe operation even during failure or movement, making the series suitable for indoor installation as well. Poles mount on a hot-dip galvanised steel base rated for high mechanical loads and an extremely long service life.

Common ratings: rated normal current up to 5000 A; rated peak withstand current up to 160 kA; short-time withstand up to 63 kA; short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operation; control voltages as for 3DN1; maintenance 25 years. All values per IEC; other values on request.

3DN3 — Pantograph disconnector (PRF & PRL / PR series)

The pantograph disconnectors PRF2 and PRL2 are characterised by their typical scissor design. Disconnecting vertically rather than horizontally allows diagonal arrangements and space-saving substation layouts; the scissors provide a highly flexible contact zone, so the pantograph works with both rigid busbars and flexible cable busbar connections.

Key features: spherical contacts for optimal, non-sensitive contact and high reliability; easy set-up thanks to factory pre-adjusted subassemblies; optional 1600 A bus-transfer capability; maintenance-free; exceeds IEC and meets GOST R and GB/DL standards.

The pantograph requires the smallest footprint of the range. High contact force delivers excellent ice-breaking and short-circuit behaviour, and corrosion-free materials (hot-dip galvanised steel, weather-proof aluminium alloys) give extremely long life. The self-interlocked end position keeps operation reliable and safe even during failure or movement, e.g. in an earthquake, and reduced casting content in the contact system lowers weight versus the previous design for easier handling.

Common ratings: rated normal current up to 5000 A; rated peak withstand current up to 160 kA; short-time withstand up to 63 kA; short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operation; control voltages as for 3DN1; maintenance 25 years. All values per IEC; other values on request.

3DN4 — Vertical-break disconnector (HBF series)

The vertical-break disconnector uses three insulating columns: two fixed columns support the fixed contacts and one rotating column turns the movable contacts. Its vertical opening permits small phase-to-phase distances, so it is mainly applied in substations with limited phase spacing; high disconnection visibility underlines its safety.

Key features: cylindrical self-resilient AgC-coated contact fingers (dry-lubricated, self-cleansing, highly reliable); a locking system with double kinematics that assures excellent contact; optional 1600 A bus-transfer capability; exceeds IEC and meets GOST R and GB/DL standards.

The current path performs two movements, locking it in the short-circuit-proof closed position and preventing it from opening under external forces. The ample distance between support and rotating insulator maintains dielectric strength of the parallel insulation even in saline fog. Installation and commissioning are quick because the movable current path is a single subassembly, pre-adjusted and routine-tested at the factory.

Common ratings: rated normal current up to 5000 A; rated peak withstand current up to 160 kA; short-time withstand up to 63 kA; short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operation; control voltages as for 3DN1; maintenance 25 years. All values per IEC; other values on request.

3DN5 — Knee-type disconnector (GBF / KR series)

Thanks to small space requirements in both vertical and horizontal directions, the knee-type disconnector is mainly applied in substations with limited phase distances. The knee joint in the main current path reduces the space needed for vertical opening and the phase distance between poles, and high disconnection visibility is proof of its safety.

Key features: robust design and simple assembly; factory pre-adjusted subassemblies; optional 1600 A bus-transfer capability; exceeds IEC and meets GB & DL standards.

The enhanced kinematic chain of the current path is easily adjustable, lubrication-free and extremely reliable in case of failure. The self-interlocked end position sits close to the main current path, ensuring reliable, safe operation even during failure or movement such as an earthquake. Maintenance-free contacts preserve conductivity in rough conditions over an extremely long service lifetime. The modular design eases on-site assembly, and a low operating moment allows manual operation with reduced effort; the double-knee variant enables a particularly compact substation design.

Common ratings: rated normal current up to 4000 A; rated peak withstand current up to 160 kA; short-time withstand up to 63 kA; short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operation; control voltages as for 3DN1; maintenance 25 years. All values per IEC; other values on request.

3DN7 — V-type disconnector (VR series)

At voltage levels below 145 kV the centre-break disconnector is barely applicable due to limited insulator distances — at minimum the contact system must be positioned (no-arm). The V-type serves exactly these applications, and wall and ceiling installations are also possible.

Key features: cylindrical self-resilient AgC-coated contact fingers (dry lubrication, self-cleansing, high reliability); easy set-up through factory pre-adjusted subassemblies; optional 1600 A bus-transfer capability; exceeds IEC and meets GB/DL standards.

The V-type is derived from the traditional centre-break type (3DN1) and inherits its main construction features and operating principle. Applied only up to 145 kV, it is a very compact and economic solution adaptable to virtually any substation layout: the space-saving, robust base frame lets all three poles be installed on a single horizontal member supported by one or two vertical columns. Add-on earthing switches must be arranged in parallel to the disconnector.

Common ratings: rated normal current up to 3150 A; rated peak withstand current up to 125 kA; short-time withstand up to 50 kA; short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operation; control voltages as for 3DN1; maintenance 25 years. All values per IEC; other values on request.

3DN8 — Side-break disconnector (SR0)

The 40.5 kV side-break disconnector, also called the SR0 series, can functionally replace the centre-break disconnector. One rotatable insulator and one fixed insulator are mounted on the switch base, and the moving arm opening to the side creates a larger phase distance than other disconnector types.

Key features: cylindrical self-resilient AgC-coated contact fingers; easy set-up via factory pre-adjusted subassemblies; maintenance-free; exceeds IEC and meets GB/DL standards. Like the double-side break, it can be customised to the substructure and delivered pre-adjusted; high contact force gives excellent ice-breaking and short-circuit behaviour, the self-interlocked end position keeps operation safe during failure or movement, and poles mount on a hot-dip galvanised steel base built for high mechanical loads and decades of service.

Common ratings: rated normal current up to 2000 A; rated peak withstand current up to 100 kA; short-time withstand up to 40 kA; short-circuit duration 1/3 s; icing class 10/20 mm; temperature range -55 … +55 °C; motor/manual operation; control voltages as for 3DN1; maintenance 25 years. All values per IEC; other values on request.

3DN9 — Semi-pantograph disconnector (YR series)

The semi-pantograph (YR type) disconnector is characterised by its semi-scissor design. Vertical rather than horizontal disconnection allows diagonal arrangement and space-saving substation design. Because the semi-pantograph provides a less flexible contact zone than the full pantograph, it is especially suited to rigid busbar connections.

Key features: the fixed contact bar is pressed by a clamp operated by a spring mechanism, guaranteeing equally controlled mechanical load and correct performance for rated and short-circuit current; factory pre-adjusted subassemblies for easy set-up; the arm is balanced by a spring housed inside its lower half for smooth, low-energy motion; optional 1600 A bus-transfer capability; exceeds IEC and meets GB/DL standards.

Its structure gives the smallest footprint requirement, and corrosion-free materials (hot-dip galvanised steel, weather-proof aluminium alloys) yield very long life. The self-interlocked end position ensures reliable, safe operation even during failure or movement, e.g. in an earthquake.

Common ratings: rated normal current up to 4000 A; rated peak withstand current up to 160 kA; short-time withstand up to 63 kA; short-circuit duration 1/3 s; icing class 10 mm; temperature range -50 … +50 °C; motor/manual operation; control voltages as for 3DN1; maintenance 25 years. All values per IEC; other values on request.

3DV6/7 and 3DV8 — Motor drives for high-voltage disconnectors

The 3DV6/7 motor operating mechanism consists of an aluminium cast housing with door, a gear unit with motor, electrical equipment and an auxiliary switch. It can also be operated manually: a hand crank is inserted into an opening accessible from the ground, secured by a swivel-mounted shutter — opening the shutter automatically interrupts the motor and control circuit, protecting site personnel against inadvertent remote operation. An electric motor brake makes manual cranking easier, and a heating resistor with internal air circulation protects against condensation. The auxiliary switches are built from creepage-proof, arc-resistant moulded plastic discs stacked into closed interrupting chambers; the self-cleaning contacts use silver-plated contact knives and bridges with solid silver elements, able to switch very small signalling currents as well as higher inductive direct currents.

The 3DV8 'smart design' motor drive uses a stainless-steel housing with the gear unit, motor and electrical components including the auxiliary switch — considered the most reliable on the market. It is form-fit connected to the gear unit for safe substation operation, offers wide space for cables and connections, is protected against condensation, and can be operated manually with little effort using a hand crank (fewer than 50 rotations).

Shared main features: easy commissioning and assembly due to pre-adjusted delivery; encapsulated worm drive for maintenance-free operation and staff safety; proven auxiliary switch for highest reliability; standard colour RAL 9006 (others available); low noise level; designed according to EN 62771-100; exceeding IEC and meeting GOST R and GB standards.

HVDC project references and the SHVC Hangzhou factory

Siemens Energy supplies customised HVDC disconnector solutions with short delivery times from its global production network. Reference projects include Gui Guang (double-side break disconnector, 6400 MW bipolar, DC 515 kV), Yun Guang (double-side break disconnector, 5000 MW bipolar, DC 824 kV), Ballia-Bhiwadi (vertical-break disconnector, DC 512 kV / 256 kV) and Cahora Bassa (pantograph disconnector, DC 600 kV).

The SHVC Hangzhou factory was founded in 1995 with a registered capital of 30 million US dollars. It holds leading R&D and production capability for high-voltage circuit breakers, semi-encapsulated compact switchgear and disconnector switches, and operates the highest-level testing centre in the Chinese power industry. Its regular business covers AC live-tank circuit breakers (72.5 kV to 550 kV, 800 kV and 1100 kV), AC dead-tank circuit breakers (72.5 kV to 550 kV), AC semi-encapsulated combined compact switchgear (DTC dead-tank compact, 72.5 kV to 252 kV, breaking capacities up to 40/50/63 kA), DC switches up to ±800 kV, and AC disconnector switches (DS) and earthing switches (ES) from 72.5 kV to 550 kV.

Siemens Energy is the main manufacturer of disconnectors and high-voltage earthing switches in China, drawing on more than 100 years of experience inherited from Siemens. In line with the global sustainability commitment, SHVC also specialises in Siemens Energy's environmentally friendly Blue series circuit breakers, which operate completely without SF6 or any other F-gases and have no toxic emissions.

Figures & drawings

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