Alternating Current
Capacitive Reactance Calculator
The purpose of Capacitive Reactance is to turn frequency, capacitance, and applied RMS voltage into capacitive reactance. Keep the source condition with the saved result so later comparisons remain meaningful.
Set up the Capacitive Reactance case
Enter ratings or measurements that describe one scenario.
From inputs to result
This page evaluates XC = 1 ÷ (2πfC); I = V ÷ XC. The participating entries are Frequency, Capacitance, and Applied RMS voltage.
The initial scenario returns 26.53 Ω. Re-enter field data before using the answer in a design or comparison.
Calculate capacitive reactance and ideal RMS current at a selected voltage. Inductive Reactance Calculator may be useful for the next related quantity.
Preparing the calculation
Record frequency, waveform, phase arrangement, and whether voltage is line or phase. Nameplate and meter values are not interchangeable unless they describe the same condition.
A denominator entry cannot be zero. Use the displayed unit for every field and document conversions separately.
- Frequency
- Default example: 60 Hz. Enter frequency in Hz.
- Capacitance
- Default example: 100 µF. Enter capacitance in µF.
- Applied RMS voltage
- Default example: 120 V. Enter applied RMS voltage in V.
Applying the result
Interpret Capacitive reactance on the same basis used for the source values. Compare it with a measured RMS case at the same frequency.
Label alternate cases rather than overwriting the baseline.
Sensitivity check
Change Frequency from 60 Hz to 72 Hz with the rest of the inputs held constant. The comparison runs from 26.53 Ω to 22.10 Ω.
The comparison demonstrates sensitivity, not a guaranteed field response.
Assumptions and limitations
ESR, tolerance, dielectric loss, and voltage dependence are not included.
Additional checks may be needed for startup transients, resonance, and measurement bandwidth. Use measurements, manufacturer data, or another calculation for effects that can change the decision.
Keep distorted-waveform measurements separate from sine-wave assumptions.
Using this result in a larger analysis
Review capacitance and the remaining entries as one case. If one value belongs to another temperature, load, or time period, separate the scenarios.
The displayed capacitive reactance should be checked against the applicable line-to-line or line-to-neutral limit. Investigate an unexpected magnitude before changing the model or adding margin.
If uncertainty remains, calculate labeled low and high cases. Include harmonics, phase imbalance, saturation, and nonsinusoidal current when those effects can change the decision.
Common questions before using the result
How should I prepare the Capacitive Reactance inputs?
Choose entries that describe the same case. Use RMS values unless an input explicitly requests peak amplitude.
Where is this capacitive reactance estimate simplified?
ESR, tolerance, dielectric loss, and voltage dependence are not included. Also consider harmonics, phase imbalance, saturation, and nonsinusoidal current.
Why does the field result disagree with this page?
Differences can come from startup transients, resonance, and measurement bandwidth, measurement uncertainty, or values taken under different conditions.