Inductor current decay

Tags

• Electronics
• physics
• Electronics formula
• physics formula
• Transients
• First-order transients

Detail

Explore the idea

Variables

• $v(t),v_0,v_\infty$voltages (V)
• $i(t),i_0,i_\infty$currents (A)
• $\tau$time constant (s)
• $t$time (s)
• $R,C,L$Ω, F, H.

Conditions

• Piecewise-constant linear first-order circuit; τ>0.

Intuitive explanation

For “Inductor current decay”: the exponential interpolates the continuous initial value and the settled value with τ.

Worked example

Common mistakes

• confusing 0⁺ with 0⁻
• using τ=L/R on an RC or τ=RC on an RL
• forgetting the settled value

Frequently asked questions

What must be checked before using the Inductor current decay relation?

Fix 0⁺, the settled value and τ of the equivalent seen by C or L.

Also known as

• RC transient, RL transient, capacitor charging, exponential discharge

Conventions

• V, A or s according to the left-hand side

Related formulas

• Related

  Inductor current build-up

  $$i_L(t)=I\left(1-e^{-tR/L}\right)$$
  Open formulaOpen in section

• Related

  Inductor voltage

  $$v_L=L\frac{di_L}{dt}$$
  Open formulaOpen in section

• Related

  RC time constant

  $$\tau=RC$$
  Open formulaOpen in section

• Related

  RL time constant

  $$\tau=\frac{L}{R}$$
  Open formulaOpen in section