Capacitor reactance and energy equations
Capacitance determines AC reactance and electrostatic energy at the entered operating point.
XC = 1/(2πfC)I = V/XCE = ½CV²Q = CVCseries = C1C2/(C1+C2)where:
- C
- Capacitance[F]
- E
- Stored energy[J]
- Q
- Stored charge[C]
Real capacitor selection requires voltage, ESR, ripple and temperature checks.
How to use the Capacitor Reactance and Energy Calculator
Calculate capacitive reactance, RMS current, stored energy, charge, peak current screen, and series or parallel equivalent capacitance. Start by choosing the operating mode, then enter values from nameplates, measurements, or project documents in the units shown. The result updates immediately and keeps intermediate quantities visible for review.
- Confirm the system and calculation mode.
- Enter measured or manufacturer-rated values.
- Review the primary result and intermediate metrics.
- Continue with the related protection or equipment-selection checks.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. Ideal capacitance Entered voltage is RMS for AC current and the selected voltage basis for energy No ESR, ripple heating, tolerance or dielectric derating A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Ideal capacitance
- Entered voltage is RMS for AC current and the selected voltage basis for energy
- No ESR, ripple heating, tolerance or dielectric derating
Selection limits and next checks
Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions. Stored energy can remain hazardous after disconnection; provide verified discharge means. AC capacitors require ripple-current, kvar, dv/dt, harmonics and resonance checks. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
Continue with rc circuit time constant calculatorContinue with rlc impedance resonance calculatorContinue with power factor correction calculator
Assumptions
- Ideal capacitance
- Entered voltage is RMS for AC current and the selected voltage basis for energy
- No ESR, ripple heating, tolerance or dielectric derating
Important Warnings
- Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions.
- Stored energy can remain hazardous after disconnection; provide verified discharge means.
- AC capacitors require ripple-current, kvar, dv/dt, harmonics and resonance checks.