電纜電壓降計算器
準確計算直流和交流電纜安裝的電壓降、功率損耗和剩餘電壓。支援銅和鋁導體，並帶有溫度修正。
輸入參數
How is Voltage Drop Calculated?
Voltage drop is calculated using Ohm's Law and the conductor's resistance. The formula takes into account the total circuit length (round-trip), load current, and conductor resistance per unit length:
- V_drop = 2 × I × L × R / 1000, where I is current in amps, L is one-way cable length in meters, and R is resistance in Ω/km
- The factor of 2 accounts for the round-trip path (current flows out and back)
- Conductor resistance increases with temperature — copper rises approximately 0.393% per °C above 20°C
- For aluminum conductors, resistance is approximately 61% higher than copper for the same gauge
This calculator also applies to single-phase AC circuits where power factor is close to 1. For three-phase systems, divide the result by √3.
常見問題
什麼是電壓降？為什麼它很重要？
電壓降是由電纜導體中的電阻引起的電壓降低。過度的電壓降會導致設備故障、效率下降和過熱。大多數標準建議將電壓降保持在3%以下。
溫度如何影響電壓降？
隨著溫度升高，導體電阻增加。銅的電阻每升高1℃約增加0.393%。環境溫度越高，相同電流下的電壓降就越大。
銅電纜和鋁電纜有什麼區別？
鋁的電導率約為銅的61%，但更輕且更便宜。對於相同的電流容量，鋁電纜需要比銅電纜大約1-2個AWG規格。
如何減少設備中的電壓降？
減少電壓降的方法：使用更大的線規、縮短電纜長度、使用銅而非鋁、或提高系統電壓。根據實際負載電流進行正確的尺寸設計至關重要。