📉

Напряжение Падение Калькулятор | Electrical Мощность Калькулятор

Рассчитать напряжение loss in electrical wires

V
A
ft
Результат
—

Формулы

1-PhaseVd = 2 × I × R × L ÷ 1000
3-PhaseVd = √3 × I × R × L ÷ 1000

NEC Guidelines

Circuit TypeMax Drop
Branch Circuits3%
Feeders2%
Итого Combined5%

Провод Сопротивление (Ω/1000ft)

AWGCopperAluminum
142.5254.04
121.5882.54
100.9991.60
80.6281.00

Связанные

Wire GaugeOhm's Law

Understanding Напряжение Drop in Electrical Circuits

Напряжение drop is the decrease in electrical напряжение that occurs when current flows through a conductor due to its inherent resistance. Every wire has some resistance that causes a portion of electrical energy to be converted into heat, resulting in lower напряжение at the load end.

Why Напряжение Падение Matters

Excessive напряжение drop can cause: dimming lights, motor overheating, equipment malfunction, reduced efficiency, and potential safety hazards. Motors are particularly sensitive - running at low напряжение causes them to draw more current, leading to overheating and premature failure.

Factors Affecting Напряжение Падение

Several factors influence напряжение drop: Wire length (longer runs = more drop), Wire size (smaller gauge = more resistance), Ток draw (higher amperage = more drop), Wire material (aluminum has ~60% more resistance than copper), and Температура (higher temps increase resistance).

How в Reduce Напряжение Падение

If your calculated напряжение drop exceeds acceptable limits: increase wire gauge, shorten wire runs, use copper instead of aluminum, increase system напряжение (240V has half the drop of 120V for same power), or run parallel conductors.

Часто задаваемые вопросы

Напряжение drop is the reduction in electrical напряжение as current flows through a wire's resistance. It matters because excessive drop causes lights to dim, motors to overheat, equipment to malfunction, and energy waste. The NEC recommends keeping напряжение drop below 3% for branch circuits and 5% total.

Per NEC recommendations: Branch circuits should have no more than 3% напряжение drop, feeders no more than 2%, and the total combined drop should not exceed 5%. For sensitive electronic equipment, aim for less than 2% напряжение drop.

For single-phase: Vdrop = (2 × K × I × L) / CM, where K is resistivity constant (12.9 copper, 21.2 aluminum), I is current, L is one-way length, CM is circular mils. For three-phase, replace 2 with 1.732 (√3). Alternatively: Vdrop = (2 × I × R × L) / 1000 using resistance per 1000 feet.

The formula already accounts for round-trip by multiplying by 2 (single-phase) or √3 (three-phase). Enter only one-way distance from source to load. The calculation automatically doubles this to account for current flowing through both hot and neutral conductors.

Copper has about 40% less resistance than aluminum, making it better for minimizing напряжение drop at the same wire gauge. However, aluminum is lighter and cheaper. To achieve equivalent performance, use aluminum wire approximately 2 AWG sizes larger than copper (e.g., #4 aluminum instead of #6 copper).

Yes, напряжение drop represents energy lost as heat in the wiring, which you pay for but don't use productively. Additionally, motors may draw more current to compensate for low напряжение, further increasing energy consumption. Minimizing напряжение drop improves efficiency and reduces operating costs.

Higher напряжение systems have lower percentage напряжение drop for the same power delivery. A 240V circuit delivering the same wattage as a 120V circuit has half the current and therefore half the напряжение drop. This is why long runs often use 240V and industrial facilities use 480V or higher.

Use the Калькулятор Сечения Провода, or calculate: CM = (2 × K × I × L) / Vdrop, where K is 12.9 for copper or 21.2 for aluminum, I is current, L is one-way length, and Vdrop = напряжение × 0.03. Match the calculated circular mils to standard wire sizes.