Single-Phase vs Three-Phase Power Basics

适用场景

Use this guide when you need fast clarity on balanced three-phase power relationships and where simplified formulas are valid.

要使用的工具

Balanced three-phase P, S, and |Q| from line quantities and cos φ.

打开 Three-Phase Power Calculator →

步骤

  1. 1Identify the measurement basis: line-to-line voltage and line current for balanced three-phase.
  2. 2Compute apparent power with S = sqrt(3)*V_LL*I_L.
  3. 3Compute real power with P = S*cos(phi) and derive reactive magnitude from the power triangle.
  4. 4State whether values are per-phase or total-system quantities.
  5. 5Use full phasor and unbalance analysis if system asymmetry is material.

示例

  • Sanity-checking panel loading assumptions during early facility planning.
  • Comparing apparent vs real power impact at different power factors.

应避免

  • Mixing phase and line quantities in one formula.
  • Treating cos(phi) as a signed reactive-direction indicator.
  • Using balanced formulas for strongly unbalanced loads.

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常见问题

Does this tell me if loads are leading or lagging?

No. The basic calculator reports reactive magnitude, not sign from full phasor context.

Can I use this for harmonics-heavy systems?

Not as final analysis; harmonics require true power-quality methods.

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