Power triangle

Tags

• Electronics
• physics
• Electronics formula
• physics formula
• potencia
• AC power and resonance
• resonancia

Detail

Explore the idea

Variables

• $P$W
• $Q$var
• $S$VA
• $V,I$RMS (V, A)
• $\theta$rad
• $\omega_0$rad/s
• $R,L,C$Ω, H, F.

Conditions

• RMS sinusoids of the same frequency; passive convention.

Intuitive explanation

For “Power triangle”: P, Q and S form the power triangle; at resonance net reactance vanishes.

Worked example

Common mistakes

• taking |S| as P
• forgetting the cos θ factor
• applying series resonance to a parallel tank

Frequently asked questions

What must be checked before using the Power triangle relation?

Use same-frequency RMS and distinguish P, Q and |S|.

Also known as

• active power, reactive power, power factor, series resonance

Conventions

• W, var, VA or dimensionless

Related formulas

• Related

  Apparent power

  $$S=VI$$
  Open formulaOpen in section

• Related

  Power factor

  $$\mathrm{FP}=\cos\theta=\frac{P}{S}$$
  Open formulaOpen in section

• Related

  RMS value of a sinusoid

  $$V_{\mathrm{rms}}=\frac{V_p}{\sqrt{2}}$$
  Open formulaOpen in section

• Related

  Phasor Ohm's law

  $$\underline V=Z\underline I$$
  Open formulaOpen in section