Substation IEC 62271-200

MV Switchgear Selection (IEC 62271-200)

AC metal-enclosed switchgear selection — Ur 3.6–40.5 kV. Panel type code, insulation levels, altitude/temperature derating, IAC classification, bay config, SF₆/vacuum/air recommendation.

⚡ IEC 60909 Short-Circuit 🔬 Relay Coordination 🔲 Busbar Rating

IEC 62271-200 IEC 62271-1 IEC 62271-100 IEC 60909 IEC 60664-1 IEC 60865-1

Presets

System Voltage & Frequency

Rated Voltage Ur (kV)

Frequency (Hz)

Rated Normal Current

Rated Normal Current Ir (A)

Reliability Requirement

Short-Circuit Withstand

Rated Short-Time Withstand Current Ik (kA)

Rated Short-Circuit Duration tk (s)

R/X Ratio (for κ factor)

Internal Arc Classification (IAC)

IAC Classification

Loss of Service Continuity

Loss of Service Continuity Category

Partition Class

Installation

Altitude (m ASL)

Environment

Ambient Temperature

Maximum Ambient Temperature (°C)

Arc Power Factor cos(φ) for Ek

Panel Type Code

Insulation Level (Table 1)

Parameter	Value
Up (impulse kV)	—
Ud (power-freq kV)	—
Ur (kV)	—

Derating Factors

Altitude Derating Ka —

Temperature Factor K_temp —

Derated Current Rating Ir (A) —

κ Factor (IEC 60909) —

Auto-Calc Ip (κ·√2·Ik) (kA) —

K_temp is indicative — verify with manufacturer curves

Internal Arc Energy

—

MJ equivalent

IAC Classification —

cos(φ_arc) —

Bay Configuration

— —

—

Insulation Technology

—

Scores

Switchgear Configuration Comparison

Standards Compliance

Export

Panel Type Code Construction ▸

The panel type code follows IEC 62271-200 §3 nomenclature: [type] [Ur] / [Ir] / [Ik-tk] [/ LSC] [- partition] [/ IAC class Ik tk]. For the 11kV industrial preset (ABB UniGear ZS1 / Schneider SM6): AIS 12kV / 1250A / 25kA-1s / LSC2B-PM / IAC AFLR 25kA 1s.

              [type] [Ur] / [Ir] / [Ik-tk] [/ LSC] [- partition] [/ IAC]
            

              AIS 12kV / 1250A / 25kA-1s / LSC2B-PM / IAC AFLR 25kA 1s
            

Insulation Levels (IEC 62271-200 Table 1) ▸

Up = rated lightning impulse withstand voltage. Ud = rated short-duration power-frequency withstand voltage. Both must be verified against the applicable altitude correction factor Ka. At H > 1000 m: Ud_corrected = Ud / Ka.

              Ud_corrected = Ud / Ka  (H > 1000 m)
            

Altitude & Temperature Derating (IEC 60664-1) ▸

Ka = e^((H-1000)/8150) for H > 1000 m. For H=2000 m: Ka=1.13 (13% derating required). K_temp ≈ 1 − 0.012 × (T_max − 40°C). Combined derating: Ir_final = Ir × Ka × K_temp.

              Ir_final = Ir × Ka × K_temp
            

Internal Arc Classification (IEC 62271-200 §6.102) ▸

Ek = √3 × Ur × Ik × t × cos(φ_arc) with cos(φ_arc) ≈ 0.7 per IEC 60865-1. The IAC classification specifies the maximum arc energy the enclosure can contain without bursting. AFLR = all faces arc-resistant.

              Ek = √3 · Ur · Ik · t · cos(φ_arc)  (cos≈0.7 per IEC 60865-1)
            

Bay Configuration Selection ▸

LSC1 → single busbar (simplest). LSC2A/2B + high reliability → double busbar. LSC2B + standard reliability → single with bypass. The single-line diagram SVG reflects the selected configuration.

FAQ

What is the difference between AIS, GIS, and RMU? +

AIS (Air-Insulated Switchgear) uses air as the primary dielectric — simple, cost-effective, larger footprint. GIS (Gas-Insulated Switchgear) uses SF₆ or alternative gases in a sealed enclosure — compact for indoor or constrained sites, higher capital cost. RMU (Ring Main Unit) is a compact 3-position switch (switch-fuse-interrupter) used in secondary distribution, typically vacuum-interrupted, pre-engineered for ring networks.

How does altitude affect switchgear current rating? +

Air density decreases with altitude, reducing the dielectric strength of air-insulated components. IEC 60664-1 §4.3 gives Ka = e^((H-1000)/8150) for H > 1000 m. For example, at 2000 m ASL, Ka ≈ 1.13 — the switchgear must be derated by ~13% or the rated voltage must be increased accordingly. At altitudes above 1000 m, always apply Ka correction.

What does IAC AFLR mean? +

IAC = Internal Arc Classification per IEC 62271-200. The letters indicate which sides are arc-resistant: A = Accessible sides, F = Front, L = Lateral, R = Rear. AFLR means all four sides are arc-resistant, protecting personnel on all faces of the panel. IAC classification is critical for switchgear installed in areas where personnel may be present during operation.

When should I specify SF₆ vs. vacuum? +

Vacuum interrupters are preferred for ratings up to Ur=40.5 kV and Ir ≤ 4000A — lower maintenance, no gas management, excellent dielectric recovery. SF₆ (or alternatives like g³) is chosen for very high short-circuit ratings (> 31.5 kA), compact indoor requirements, or where the sealed enclosure provides better arc containment. EU F-gas regulations are driving adoption of vacuum for new installations below 52 kV.

What is LSC2B vs. LSC1? +

LSC (Loss of Service Continuity) per IEC 62271-200 §3.112: LSC1 = no transfer busbar, supply is interrupted during maintenance of any functional unit. LSC2A/2B = transfer busbar available so the load can be maintained via alternative path. LSC2B is the preferred category for modern distribution switchgear as it enables feeder maintenance without supply interruption.

How is the panel type code constructed? +

IEC 62271-200 nomenclature: [type] [Ur] / [Ir] / [Ik-tk] [/ IAC] [/ LSC] [- partition]. Example: "AIS 12kV / 1250A / 25kA-1s / LSC2B-PM / IAC AFLR 25kA 1s" — this reads as: Air-insulated, 12 kV rated, 1250 A normal current, 25 kA for 1 s, loss of service continuity 2B with metal partition, arc-resistant on all four sides. This matches ABB UniGear ZS1 and Schneider SM6 12 kV configurations.