Choose language

PL, EN, ES, DE, FR, RU

# Voltage drop from current, single-phase and three-phase current, cable length, cross-section or diameter

With this calculator you can calculate voltage drops for single-phase and three-phase AC circuits calculated from the rated current. You will also calculate wire length, wire diameter, wire cross-sectional area, voltage or current.

## Voltage drop calculator from current for single-phase and three-phase circuits - information

Voltage drop - voltage reduction in electricity, that is, the difference in electric potential between two points in the circuit where an electric current flows.

It is also a concept which in the energy sector can mean:
- reduction of the electric voltage between the beginning and the end of the supply line,
- voltage reduction below the rated voltage for a given power network.

Relative voltage drop is the ratio of voltage drop to rated voltage. The acceptable voltage drop at rated load on the transmission line from the transformer to the electricity consumer must be less than 5% of the rated voltage.

Electric energy receivers, to ensure their correct operation, should be supplied with voltage close to the rated voltage. This sometimes requires the use of cables with a cross-section greater than the current carrying capacity. The permissible voltage drop in non-industrial electrical installations in receiving circuits, from a meter to any receiver, according to N-SEP-E-002, should not exceed 3%, and from the meter to a connector 0.5%, with power transmitted up to 100 kVA and 1 % at a power greater than 100 kVA and less than 250 kVA.

For circuits made with cables, multi-core or single-core conductors with a conductor cross-section not exceeding 50 mm² Cu (copper) and 70 mm² Al (aluminum), the reactances of these conductors are ignored.

Assuming the above assumption, the voltage drops are calculated from the dependence:

for single-phase circuits:
$$\Delta U_\%=\frac{200 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot S \cdot U_{n}}$$

for three-phase circuits:
$$\Delta U_\%=\frac{\sqrt{3} \cdot 100 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot S \cdot U_{n}}$$

where:
ΔU% – voltage drop [%],
L – wire length [m],
In - rated current [A],
Un - rated voltage [V],
S – cross-sectional area of the line veins [mm²],
d - wire diameter,
σ – conductivity of the conductor [m/Ωmm²],
cosφ – phase shift factor,

Given the diameter of a conductor, the cross-sectional area of a conductor can be calculated using the formula:

$$S = \frac{\pi \cdot d^2}{4}$$

where:
S – conductor cross-sectional area,
d – conductor diameter,

Conductivity (specific conductivity, specific electrical conductivity) is a physical quantity that characterizes the electrical conductivity of a material.

After transformations for single-phase circuits:

Wire diameter:
$$d = \sqrt {\frac{800 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot \Delta U_\% \cdot U_{n} \cdot \pi}}$$

Rated current:
$$I_n = \frac{\sigma \cdot \Delta U_\% \cdot U_{n} \cdot S}{200 \cdot L \cdot \cos \phi}$$

Wire length:
$$L = \frac{\sigma \cdot \Delta U_\% \cdot U_{n} \cdot S}{200 \cdot I_n \cdot \cos \phi}$$

Rated voltage:
$$U_{n}=\sqrt {\frac{200 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot \Delta U_\% \cdot S}}$$

Cross-sectional area:
$$S=\frac{200 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot \Delta U_\% \cdot U_{n}}$$

After transformations for three-phase circuits:

Wire diameter:
$$d = \sqrt {\frac{\sqrt{3} \cdot 400 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot \Delta U_\% \cdot U_{n} \cdot \pi}}$$

Rated current:
$$I_n = \frac{\sigma \cdot \Delta U_\% \cdot U_{n} \cdot S}{\sqrt{3} \cdot 100 \cdot L \cdot \cos \phi}$$

Wire length:
$$L = \frac{\sigma \cdot \Delta U_\% \cdot U_{n} \cdot S}{\sqrt{3} \cdot 100 \cdot I_n \cdot \cos \phi}$$

Rated voltage:
$$U_{n}=\sqrt {\frac{\sqrt{3} \cdot 100 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot \Delta U_\% \cdot S}}$$

Cross-sectional area:
$$S=\frac{\sqrt{3} \cdot 100 \cdot I_n \cdot L \cdot \cos \phi}{\sigma \cdot \Delta U_\% \cdot U_{n}}$$

## Users of this calculator also used

### Resistance, length and diameter of wire calculator

With this calculator, you can calculate the resistance of the cable, knowing the material it is made of. You can also calculate the length of the conductor and the conductor diameter or the conductor cross-section area.

### Matrix 3x3 calculator

Thanks to the 3x3 matrix math calculator, you can easily calculate the determinant of the matrix 3x3, find the complement 3x3 matrix, transpose 3x3 matrix, inverse 3x3 matrix.

### Storm distance, lightning distance calculator. How far is the storm?

How far is the storm? How close is lightning? Is the storm looming or is it moving away? Surely everyone has asked themselves such questions. That is why we have created a lightning distance calculator with which you can easily check it.

### Voltage drop calculator for single-phase and three-phase circuits

With this calculator you will calculate the voltage drops for single-phase and three-phase AC circuits calculated from active power. You will also calculate cable length, conductor diameter, conductor cross-sectional area, phase or line voltage or active power.

### Rail Fence, Zig-Zag - encoder / decoder

Rail Fence, Zig-Zag cipher online encoder and decoder. Encrypt and decrypt any cipher created in a Rail Fence, Zig-Zag cipher.

### COSINE calculator

With the COSINE Trigonometric Calculator you can calculate the values of any cosine function. In addition to the response results, the calculator will also plot the selected function. You can choose one of the preset functions, e.g. cosine, cos 2 - cosine square, arccos - arccosine, cosh - hyperbolic cosine, arcosh - function inverse to cosh, you can also enter your own function, e.g. cos(x ) * cos(x) * cos(x) for cos3(x), cos(2x), cos(x+3), cos(x^2) etc.

### Morse code translator, encoder-decoder

With the converter, you can quickly translate any sentence into Morse code and vice versa. You can listen to the translated code, see it thanks to the light signals or, using the phone, feel it through vibration. Morse code is used nowadays mainly in amateur radio, it is also useful in many other areas of life.