Calcolatrice Caduta di Tensione Gratuita
Calcola la caduta di tensione in un cavo elettrico.
Voltage Drop
3.45 V
Voltage Drop vs Load Current (I)
Formula
Cable Voltage Drop
Voltage drop occurs as current flows through the resistance of cable conductors.
Formulas
Single phase: V_drop = 2 I L R_cable / 1000
Three phase: V_drop = sqrt(3) I L R_cable / 1000
where I is current, L is one-way length in metres, and R_cable is resistance in ohms/km. The factor of 2 in single-phase accounts for the return conductor. Most codes limit voltage drop to 3-5% of supply voltage.
Esempio Risolto
Single phase, 30 A load, 50 m cable run, cable resistance 1.15 ohm/km.
- 01V_drop = 2 x 30 x 50 x 1.15 / 1000 = 3.45 V
- 02Percentage = 3.45 / 230 x 100 = 1.50%
- 03This is within the typical 3% limit.
Domande Frequenti
What is the maximum allowable voltage drop?
Most electrical codes allow 3% for branch circuits, 2% for feeders, and 5% total from service entry to final outlet. Some critical equipment may require tighter limits (1-2%).
How do I find cable resistance per km?
Cable manufacturers publish tables of resistance per km for each cable size and conductor material. Copper is about 60% less resistive than aluminium. Resistance increases with temperature.
What if voltage drop is too high?
Increase the cable size (lower resistance per km), reduce the cable length (relocate the panel closer), or increase the voltage (use 400V three-phase instead of 230V single-phase).
Impara