Siemens NXAIR air-insulated switchgear family
Siemens NXAIR metal-clad switchgear family, from 17.5 kV at 50 kA to the 36 kV NXAIR H, inherently SF6-free
Siemens NXAIR air-insulated switchgear family is one of 41 data center switchgear tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.
Siemens NXAIR dossier: air-insulated metal-clad family from 17.5 kV at 50 kA to 36 kV NXAIR H, attribution correction, spares channels, inspection.
Why it matters
NXAIR is Siemens' volume answer to UniGear and PIX, and its air-plus-vacuum construction makes it F-gas-proof without a 'blue' variant, an underappreciated procurement angle as SF6 rules tighten. The 50 kA tier covers dense-fault urban networks that most AIS families cannot serve.
Who buys it
IEC-market utilities, industrials, and campus projects specify NXAIR across its five variants; US exposure arrives via imported process skids and IEC-spec colocation builds. Used demand centers on withdrawable breakers and panel spares for installed lineups.
Role in the data center
Primary MV distribution for IEC-market campuses, with the 50 kA tier serving high-fault-density urban interconnects.
Key specifications
| Base family | 17.5 kV / 4,000 A / 40 kA |
|---|---|
| 50 kA tier | 17.5 kV / 4,000 A / 50 kA |
| NXAIR M | 24 kV / to 25 kA |
| NXAIR C | 24 kV / 2,000 A / 25 kA |
| NXAIR H | 36 kV / 2,900 A / 31.5 kA |
| Insulation | air + vacuum (SF6-free) |
| Arc containment | IEC 62271-200 type-tested |
| Digital options | IEC 61869 LPIT, condition monitoring |
| Owner correction | Siemens AG Smart Infrastructure |
Technical summary
NXAIR: to 17.5 kV / 4,000 A / 40 kA NXAIR 50 kA: 17.5 kV / 4,000 A / 50 kA NXAIR M: 24 kV / up to 25 kA NXAIR C: 24 kV / 2,000 A / 25 kA NXAIR H: 36 kV / 2,900 A / 31.5 kA Insulation: natural air + vacuum interrupters (SF6-free by construction) Arc containment: IEC 62271-200 type-tested (IAC) Digital options: IEC 61869 LPIT sensors, condition monitoring Construction: withdrawable vacuum breakers, metal-clad panels Owner: Siemens AG Smart Infrastructure
Pricing and availability
Trend: up Lead time, new: 52-80 weeks (metal-clad class). Lead time, used or refurbished: Quote-only overseas resellers; no US channel. Warranty, used: 1-year typical from reconditioning dealers.
Lifecycle and maintenance
Metal-clad MV switchgear routinely serves 40+ years: vacuum interrupters rated for 10,000-30,000 operations far outlast the mechanical duty standby service imposes, so lineup life is governed by insulation condition and relay/controls vintage. Breakers recondition readily and trade as units, while lineups modernize in place with digital relays and retrofit breakers. ANSI/NETA MTS acceptance testing at purchase plus PD surveys in service are the condition gates.
Common failure points
- Vacuum interrupters — Loss of vacuum ends interrupting capability with no external sign
- Insulation tracking and PD — Partial discharge across dusty or damp insulation progressing to flashover
- Racking and interlocks — Damaged racking screws and defeated interlocks from forced operation
- Protection relays — Obsolete or drifted relays mis-operate under fault
- Instrument transformers — CT/VT failures disable metering and protection inputs
- Space heater failure — Condensation-driven tracking in unheated outdoor or humid gear
Inspection checklist
Vacuum integrity — hipot test each interrupter per OEM procedure (e.g., 36 kV test on 15 kV class) Insulation resistance — megger bus and breakers at 2,500-5,000 V; compare to ANSI/NETA MTS tables Contact resistance — micro-ohm each pole; investigate imbalance beyond 50% between phases Partial discharge — ultrasonic and TEV survey; investigate any reading 6 dB above baseline Contact erosion — measure vacuum interrupter erosion marks against the OEM wear allowance Racking mechanism — cycle connect/test/disconnect positions 3 times each; verify interlocks and shutters Mechanism timing — verify open/close times; closing beyond 5 cycles flags mechanism trouble Bus insulation — inspect epoxy and boots for tracking or corona; clean and torque joints Instrument transformers — verify CT/VT ratios, insulation, and fusing Protection relays — test to calibration cycle; electromechanical relays need 1-2 year intervals Arc rating — confirm arc-resistant construction class (IEEE C37.20.7 Type 2B) matches the installation Heaters — verify space heaters work; condensation drives tracking failures in unheated gear Nameplate — confirm voltage class, BIL (60-150 kV by class), and interrupting rating against the application Standards — verify IEEE C37.20.2 construction and UL/CSA labels; run ANSI/NETA MTS acceptance tests Records — factory test report, maintenance history, and operation counts; missing history reprices as-is