三相功率计算器 — 公式

Three-Phase Power Calculations

Three-phase systems are the standard for industrial power distribution.

Formulas

P = sqrt(3) x V_LL x I x cos(phi) (real power in watts)

S = sqrt(3) x V_LL x I (apparent power in VA)

Q = sqrt(3) x V_LL x I x sin(phi) (reactive power in VAR)

where V_LL is the line-to-line voltage, I is the line current, and cos(phi) is the power factor. These apply to balanced loads.

计算示例

A 400 V three-phase supply with 50 A line current at 0.85 power factor.

  1. S = sqrt(3) x 400 x 50 = 34,641 VA = 34.64 kVA
  2. P = 34,641 x 0.85 = 29,445 W = 29.44 kW
  3. Q = 34,641 x sin(acos(0.85)) = 34,641 x 0.5268 = 18.25 kVAR