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Three-Phase Power Calculator

Science & Engineering

P=√3UIcosφ + star/delta

Quick Answer

Three-Phase Power Calculator: P=√3UIcosφ + star/delta. Three-Phase Power Calculator uses standard science & engineering formulas to compute accurate results instantly.

Solve for power P
5,594.52 W
In kW5.59 kW
Apparent S6582 VA

Calculation steps

  1. 1P = √3·U·I·cosφ = 1.732 × 380 × 10 × 0.85 = 5595 W
  2. 2Apparent power S = √3·U·I = 6582 VA; reactive Q = √(S²−P²) = 3467 var

Star (Y) vs Delta (△) connection

QuantityStar (Y)Delta (△)
线电压 U 与相电压 UφU = √3 × Uφ（380/220）U = Uφ
线电流 I 与相电流 IφI = IφI = √3 × Iφ
总功率公式P = √3·U·I·cosφ（统一用线值）P = √3·U·I·cosφ
典型用途380/220V 低压配电电机大功率运行/降压启动切换

Motor power → rated current (380V, cosφ 0.8)

1.5 kW 电机≈ 3.4 A（cosφ 0.8）
4 kW 电机≈ 9.1 A
7.5 kW 电机≈ 15.2 A
15 kW 电机≈ 30 A
30 kW 电机≈ 60 A
75 kW 电机≈ 150 A
The √3·U·I·cosφ formula uses LINE voltage and LINE current for both star and delta — no need to convert. China low-voltage systems: line voltage 380 V, phase voltage 220 V. Motor starting current is 5-7× rated, so size breakers accordingly; running motors significantly under load drops cosφ sharply (below 0.5), wasting reactive capacity.

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How to Use

  1. Enter known quantities: fill values and confirm units in the Three-Phase Power Calculator.
  2. Instant solution: unknowns solve live with the formula shown transparently.
  3. Use constant/material tables: standard physical constants and material data are listed on this page.
  4. Compare conditions: change inputs to compare scenarios.

Key Points

  • Three-Phase Power Calculator is a free online science & engineering tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: P=√3UIcosφ + star/delta.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Three-Phase Power Calculator formula

Three-Phase Power Calculator uses standard science & engineering formulas to compute accurate results instantly.

FAQ

How do I use the Three-Phase Power Calculator?
Open the page and fill in the input fields — results update automatically. P=√3UIcosφ + star/delta.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on CODATA recommended constants and standard physics formulas. Last updated: 2025-07

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. Three-Phase Power Calculator[EB/OL]. https://www.yijiansuan.com/en/c/science/three-phase

Results provided by this tool are for reference only and do not constitute professional advice.