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Alternating Current

Series RL Impedance Calculator

Series RL Impedance is a worksheet for comparing one electrical condition at a time, with the result tied to its inputs.

Set up the Series RL Impedance case

Use measured values for Series RL Impedance when available and rated values only when they describe the same condition.

Ω

Enter resistance in Ω.

Hz

Enter frequency in Hz.

H

Enter inductance in H.

Where Series RL Impedance fits

Series RL Impedance turns the visible entries into impedance magnitude. It works best as a comparison tool where each run has a clear measurement basis.

On Series RL Impedance, keep the waveform basis visible: RMS, peak, frequency, and phase terms are not interchangeable.

If two cases differ in resistance, save them as separate runs. A blended entry can hide the reason the impedance magnitude changed.

Testing inductance

Using the sample values, Resistance = 20 Ω; Frequency = 60 Hz; Inductance = 0.08 H, the primary result is 36.19 Ω.

Baseline36.19 Ω
Change Resistance23 Ω
New result37.93 Ω

This Series RL Impedance one-input test is a scale check, showing direction and sensitivity without turning the changed case into a recommendation.

If the changed frequency comes from a real measurement, keep the original Series RL Impedance run so the source of the difference remains clear.

Unit handling for Series RL Impedance

|Z| = √(R² + XL²)

The formula uses Resistance, Frequency, and Inductance to produce Impedance magnitude. Unit mistakes usually show up as an answer that is off by a factor of 10, 100, or 1,000.

The Impedance magnitude value and any supporting metrics belong to this same Series RL Impedance case, not to a nearby run with different inputs.

Displayed valueDefault case
Impedance magnitude36.19 Ω
Inductive reactance30.16 Ω

When the scope changes, move to Series RC Impedance and leave this run as the original reference.

Source notes for Series RL Impedance

Collect Resistance, Frequency, and Inductance from the same operating case before reading impedance magnitude.

Resistance
Enter resistance in Ω. Default shown: 20 Ω.
Frequency
Enter frequency in Hz. Default shown: 60 Hz.
Inductance
Enter inductance in H. Default shown: 0.08 H.

When your notes point to Parallel RLC Impedance, open it after saving this baseline so the two cases do not get mixed.

Interpreting Series RL Impedance

If impedance magnitude is near a limit, preserve the calculated value from Series RL Impedance and apply required margin after the calculation.

What Series RL Impedance leaves out

The result assumes sinusoidal steady-state operation.

  • Phase reference mistakes
  • Instrument bandwidth

A numerically valid Series RL Impedance result can still be wrong if the field condition, connection type, tariff period, or equipment rating does not match.

If this answer becomes an input to Series RLC Impedance, copy the value with its units and source note attached.