⚡ Calculadora de corriente de cortocircuito
Calcule la corriente de cortocircuito prevista a partir del kVA y la impedancia del transformador, y obtenga la corriente nominal y el poder de corte del interruptor — en tamaños estándar IEC o NEC.
⚙️ Transformador & Sistema
📊 Result
Para diseñadores y contratistas que dimensionan aparamenta de baja tensión e interruptores frente al nivel de falta.
Cómo se calcula
· Corriente nominal: In = kVA ÷ (√3 × U).
· Corriente de cortocircuito: Isc = In ÷ (Z%/100).
· Corriente de pico: ip ≈ 2.5 × Isc; calibre del interruptor ≥ 1.25 × In y poder de corte ≥ Isc.
Normas de referencia
| Standard | Scope |
|---|---|
| IEC 60909 | Cálculo de corrientes de cortocircuito en sistemas trifásicos de CA |
| IEC 60947-2 | Interruptores automáticos de baja tensión — poder de corte asignado |
| NEC 110.9 | Capacidad de interrupción de los dispositivos de protección contra sobrecorriente |
Ejemplo resuelto — transformador de 1000 kVA → falta de 24 kA
1. 1000 kVA, 0.4 kV, Z = 6% → In = 1000 ÷ (√3 × 0.4) = 1443 A.
2. Isc = 1443 ÷ 0.06 = 24.1 kA; pico ip ≈ 2.5 × 24.1 = 60 kA.
3. Calibre del interruptor = 1600 A (IEC) con poder de corte de 25 kA.
4. Armario de baja tensión recomendado: GGD-1600.
FAQ
How do I calculate short-circuit current?
Use IEC 60909: short-circuit current = voltage / (sqrt(3) x total impedance). For a 0.4 kV system, the Transformer impedance dominates. A 1000 kVA, 6% impedance transformer contributes about 24 kA at the LV bus (1000 / (sqrt3 x 0.4 x 0.06) ~ 24 kA). The calculator computes three-phase and single-phase fault currents.
What breaker breaking capacity do I need?
The breaker breaking capacity must exceed the prospective Fault Current at its location. For 24 kA at the bus, select a 36 kA breaker (standard IEC 60947 ratings are 16/25/36/50 kA). Undersizing risks a failure to interrupt a fault, so use a 1.25-1.5 safety margin. The calculator matches the breaker to the fault level.
What is the difference between Icu and Ics?
Icu is the ultimate breaking capacity — the breaker can interrupt it once but may need replacement. Ics is the service breaking capacity — the breaker can interrupt it repeatedly and remain usable. Ics is typically 50-75% of Icu. Select breakers whose Icu exceeds the fault level; the calculator checks against standard ratings.
How does cable length reduce short-circuit current?
Long cables add impedance that reduces fault current downstream. A 50 m run of 35 mm2 copper cable can cut a 24 kA fault to roughly 15-18 kA at the far end. This is why downstream breakers can be lower-rated. The calculator accounts for cable impedance when computing the fault level at the load.
What is the difference between symmetrical and asymmetrical fault current?
Symmetrical fault current is the steady AC component; asymmetrical adds a decaying DC offset, peaking in the first half-cycle. The peak (making) current is 1.5-2.5 times the RMS symmetrical value, so Switchgear has both a breaking (Isc) and a making (peak) rating. IEC 60909 computes both; the calculator reports the symmetrical level for breaker selection.
Insertar esta calculadora
Añada esta calculadora a su propio sitio web de forma gratuita. El iframe se adapta a cualquier ancho y se ejecuta íntegramente en el navegador de sus visitantes.
Herramientas relacionadas
Estimaciones de referencia (FOB Qingdao, EXW) solo para diseño preliminar — no constituyen una cotización final. Confirme el dimensionamiento según su proyecto y las normas locales.
Send my complete design report
Get the full bill of materials, single-line diagram, calculation steps and FOB pricing as a PDF — free, no sign-up.
Your data stays private. No spam — only a reply to your enquiry.