🔗 Calculadora de caída de tensión
Dimensione un cable por capacidad de corriente y caída de tensión en una sola pasada. Elija corriente, longitud y conductor, y obtenga la sección mínima que se mantiene dentro de su límite de caída de tensión.
⚙️ Circuit
📊 Result
Para electricistas e ingenieros que dimensionan alimentadores de baja tensión y circuitos finales.
Cómo se calcula
· Resistencia: R = ρ ÷ A (ρ cobre 0.0225, aluminio 0.036 Ω·mm²/m).
· Caída de tensión: VD = √3·I·L·R (trifásico) o VD = 2·I·L·R (monofásico).
· Caída de tensión %: VD% = VD ÷ U × 100 (U = 400 V o 230 V).
Normas de referencia
| Standard | Scope |
|---|---|
| IEC 60364-5-52 | Sistemas de cableado — capacidades de corriente admisible y caída de tensión |
Ejemplo resuelto — 100 A en 50 m → 25 mm² de cobre
1. 100 A, 50 m, cobre trifásico, límite del 3%.
2. Primero la capacidad: 25 mm² de cobre admite 101 A ≥ 100 A.
3. R = 0.0225 ÷ 25 = 0.0009 Ω/m → VD = √3 × 100 × 50 × 0.0009 = 7.8 V = 1.95%.
4. 25 mm² cumple tanto la capacidad de corriente como el límite de caída del 3%.
FAQ
What is an acceptable voltage drop in a low-voltage circuit?
IEC 60364-5-52 recommends total voltage drop within 5% (distribution plus final circuit), and 3% for lighting. In practice feeders are sized for 2-3% steady-state drop, leaving margin for motor starting. The calculator computes drop for single and three-phase circuits and recommends a cross-section that meets the limit.
How do I calculate voltage drop for a 3-phase circuit?
Voltage drop = sqrt(3) x I x L x (R cos(phi) + X sin(phi)). For a 100 A, 50 m, 35 mm2 copper feeder (R ~0.524 ohm/km), drop is about 1.73 x 100 x 0.05 x 0.524 = 4.5 V, or 1.1% of 400 V. The calculator computes drop in volts and percent and flags the recommended section.
Copper or aluminum for a feeder cable?
Aluminium is lighter and cheaper (30-50% less) but needs a larger cross-section for the same drop because its resistivity is ~1.6x copper. For a 100 A feeder, 35 mm2 copper roughly equals 50-70 mm2 aluminium. Copper wins in ducts and short runs; aluminium wins in long, cost-driven feeders. The calculator compares both.
How does motor starting affect voltage drop?
Motor starting current is 5-7 times rated, so the starting voltage drop is 5-7 times the steady-state drop. A feeder sized for 2% running drop may dip 10-15% during start, which can stall the motor. Soft-starters or larger cables limit this. The calculator flags starting drop and recommends mitigation.
What cross-section do I need for a 100 A three-phase feeder?
For a 100 A, 0.4 kV three-phase feeder, a 35 mm2 copper cable is the standard choice, carrying ~110-125 A with a 50 m run dropping about 1%. For longer runs or tighter drop limits, use 50 mm2. The calculator picks the minimum section meeting both ampacity and drop per IEC 60364-5-52.
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.