Medium-Voltage Switchgear Type NXPLUS C Wind Features & Requirements

By | February 11, 2018

Siemens Fixed-Mounted Circuit-Breaker Switchgear Type NXPLUS C Wind up to 36 kV, Gas-Insulated.

Environmental independence

Hermetically tight, welded switchgear vessels made of stainless steel as well as single-pole solid insulation make the parts
of the primary circuit under high voltage of NXPLUS C Wind switchgear

Insensitive to certain aggressive ambient conditions, such as:
– Saline air
– Air humidity
– Dust
– Condensation

Tight to ingress of foreign objects, such as:
– Dust
– Pollution
– Small animals
– Humidity

Independent of the site altitude.

Compact design

Thanks to the use of SF6 insulation, compact dimensions are possible. This is the basic prerequisite for application in wind turbines. For installation or removal, it must be possible to bring the switchgear in through the door of the wind turbine.

Maintenance-free design

Switchgear vessels designed as sealed pressure systems, maintenance-free switching devices and enclosed cable plugs ensure:
• Maximum supply reliability
• Personnel safety
•  Sealed-for-life design according to IEC 62271-200 (sealed pressure system)
•  Installation, operation, extension and replacement without SF6 gas work
• Reduced operating costs
• Cost-efficient investment
• No maintenance cycles.


The use of digital secondary systems and combined protection and control devices ensures:

  • Clear integration in process control systems
  • Flexible and highly simplified adaptation to new system conditions and thus to cost-efficient operation.

Service life

Under normal operating conditions, the expected service life of the gas-insulated switchgear NXPLUS C Wind is at least 35 years, probably 40 to 50 years, taking the tightness of the hermetically welded switchgear vessel into account. The service life is limited by the maximum number of operating cycles of the switching devices installed:

  • For circuit-breakers according to the endurance class defined in IEC 62271-100
  • For three-position disconnectors and earthing switches according to the endurance class defined in IEC 62271-102
  • For three-position switch-disconnectors and earthing switches according to the endurance class defined in IEC 62271-103 and IEC 62271-102.

Personal safety

  • Safe-to-touch and hermetically sealed primary enclosure
  • Cable terminations, busbars and voltage transformers are surrounded by earthed layers
  • All high-voltage parts including the cable terminations, busbars and voltage transformers are metal-enclosed
  • Capacitive voltage detecting system to verify safe isolation from supply
  • Operating mechanisms and auxiliary switches safely accessible outside the primary enclosure (switchgear vessel)
  • Due to the system design, operation is only possible with closed switchgear enclosure
  • Standard degree of protection IP 65 for all high-voltage parts of the primary circuit, IP 3XD for the switchgear enclosure
    according to IEC 60529 and VDE 0470-1
  • High resistance to internal arcs by logical mechanical interlocks and tested switchgear enclosure
  • Panels tested for resistance to internal faults up to 25 kA
  • Logical mechanical interlocks prevent maloperation
  • Make-proof earthing by means of the circuit-breaker or the three-position switch-disconnector.

Security of operation

  • Hermetically sealed primary enclosure independent of environmental effects (pollution, humidity and small animals)
  • Maintenance-free in an indoor environment (IEC 62271-1 and VDE 0671-1)
  • Operating mechanisms of switching devices accessible outside the primary enclosure (switchgear vessel)
  • Metal-enclosed, plug-in inductive voltage transformers mounted outside the SF6 switchgear vessel
  • Current transformers as ring-core current transformers mounted outside the SF6 switchgear vessel
  • Complete switchgear interlocking system with logical mechanical interlocks
  • Welded switchgear vessels, sealed for life
  • Minimum fire load
  • Type and routine-tested
  • Standardized, NC production processes
  • Quality assurance in accordance with DIN EN ISO 9001
  • More than 500,000 switchgear panels of Siemens in operation worldwide for many years
  • Option: Aseismic design.


  • 3-pole enclosure of the primary part consisting of a switchgear vessel made of stainless steel
  • Insulating gas SF6
  • Three-position switch as busbar disconnector and feeder earthing switch
  • Make-proof earthing by means of the vacuum circuit-breaker
  • Compact dimensions due to SF6 insulation
  • Hermetically tight, welded switchgear vessel made of stainless steel
  • 1-pole, solid-insulated, screened busbars, plug-in type
  • Cable connection with outside-cone plug-in system
  • Wall-standing or free-standing arrangement
  • Cable connection access from front
  • Low-voltage door hinge on the left and on the right
  • Installation and extension of existing switchgear at both ends without gas work and without modifi cation of existing panels.


•  According to IEC 62271-200 and VDE 0671-200
• Logical mechanical interlocks prevent maloperation
•  Three-position disconnector can only be operated with circuit-breaker in OPEN position
•  Circuit-breaker can only be operated with three-position switch in end position and operating lever removed
•  Three-position disconnector interlocked against the circuit-breaker in circuit-breaker panels
•  “Feeder earthed“ locking device
•  Locking device for three-position switch

The following interlocks can be fulfilled by placing the padlock accordingly:

Padlock on the left: Three-position switch “DISCONNECTING” function cannot be operated, three-position switch “READY-TO-EARTH” function can be operated

Padlock in the center: Control gate blocked, no switching operations possible

Padlock on the right: Three-position switch “DISCONNECTING” function can be operated, three-position switch “READY-TO-EARTH” function cannot be operated

Option: Cable compartment cover interlocked against the three-position switch (circuit-breaker panel, disconnector panel, ring-main panel)

Option: Electromagnetic interlocks

Option: Actuating openings can be padlocked

Option: “Feeder earthed“ locking device.

Modular design

  • Panel replacement possible without SF6 gas work
  • Low-voltage compartment removable, plug-in bus wires.

Instrument transformers

  • Current transformers not subjected to dielectric stress
  • Easy replacement of current transformers designed as ring-core transformers
  • Voltage transformers metal-enclosed, plug-in type.

Vacuum circuit-breaker

  • Maintenance-free under normal ambient conditions according to IEC 62271-1 and VDE 0671-1
  • No re-lubrication or readjustment
  • Up to 2000 operating cycles
  • Vacuum-tight for life.

Secondary systems

  • Customary protection, measuring and control equipment
  • Option: Numerical multi function protection relay with integrated protection, control, communication, operating and monitoring functions
  • Can be integrated in process control systems.


Standards NXPLUS C Wind Switchgear

Switchgear installation options

For single-busbar applications:

– Wall-standing arrangement or

– Free-standing arrangement.

Room height
≥ 2400 mm all switchgear assemblies without busbar voltage transformer
≥ 2700 mm all switchgear assemblies with busbar voltage transformer

Door dimensions: The door dimensions depend on the dimensions of the individual panels (see page 11 of full manual).

Switchgear fixing

  • For floor openings and fixing points of the switchgear, see page 11
  • Foundations:
    – Steel girder construction
    – Steel-reinforced concrete with foundation rails, welded or bolted on.


NXPLUS C Wind switchgear is delivered in form of individual panels, or as a panel combination with a maximum width of 1500 mm. Please observe the following:
•  Transport facilities on site
•  Transport dimensions and transport weights
•  During the transport of panel groups, the corresponding transport rods must be used
•  Size of door openings in building.

PackingMedium-Voltage Switchgear Type NXPLUS C Wind Features & Requirements

Means of transport: Rail and truck
– Panels on pallets
– Open packing with PE protective foil.

Means of transport: Ship
– Panels on pallets
– In closed crates with sealed upper and lower PE protective foil
– With desiccant bags
– With sealed wooden base
– Max. storage time: 6 months.

Means of transport: Container
– Panels on pallets
– With sealed upper and lower PE protective foil
– With desiccant bags.

Means of transport: Airplane
– Panels on pallets
– In wooden latticed crate with sealed upper and lower PE protective foil
– With desiccant bags.

Complete technical catalogue is available at Siemens Website.

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