RL Time Constant
Compute the time constant τ of a first-order RL circuit from L (mH) and R (Ω).
Inputs
Formula
τ = L/R (with unit scaling)
τ is the time to reach ~63% of final current.
Fundamentals
Compute the time constant τ of a first-order RL circuit from L (mH) and R (Ω).
This tool computes RL Time Constant from the formula: τ = L/R (with unit scaling)
History
Design theory of gears, threads and bearings matured with machine tools and standardisation (AGMA, ISO) since the Industrial Revolution.
Engineering applications
Used for transmission design, joint strength checks and component selection.
Glossary
| Inductance L | Input parameter |
| Resistance R | Input parameter |
| Time const. τ | Output result |
How to use
- Fill in Inductance L, Resistance R in the Inputs section (watch the unit on each field).
- Click Calculate; the tool evaluates the formula shown above.
- Read Time const. τ in the results area.
Formula · Worked Example · Knowledge
Formula
核心计算关系：τ = L/R (with unit scaling)
输入变量：
- Inductance L
L— mH - Resistance R
R— Ω
输出结果：
- Time const. τ
tau— ms
假设/适用：Gearing/thread formulas assume standard, zero-backlash mounting; include error & load factors K_A.
Worked Example
根据公式 τ = L/R (with unit scaling)，取 Inductance L = 100 mH；Resistance R = 10 Ω。
代入计算得：Time const. τ = 10 ms。
Key Points
- Gearing/thread formulas assume standard, zero-backlash mounting; include error & load factors K_A.
- Compare stress with allowable stress and keep a safety factor (≥1.5, ≥2 for critical parts).
- For high speed/load also check lubrication, heat and fatigue life, not just static strength.
Parameters
Inputs
| Parameter | Symbol | Unit | Default |
|---|---|---|---|
| Inductance L (mH) | L | mH | 100 |
| Resistance R (Ω) | R | Ω | 10 |
Outputs
| Result | Symbol | Unit |
|---|---|---|
| Time const. τ | tau | ms |
Applications
- Common engineering use cases
FAQ
What formula does this tool use?
This tool computes per ISO / AGMA / ASME standard formulas: τ = L/R (with unit scaling)
How accurate are the results?
Results match input precision, based on SI units and common engineering approximations; for critical duty re-check with a safety factor.
Where is it used?
Common engineering use cases