Capacitive Reactance Calculation

The following calculation can be used to calculate the capacitive reactance of a single phase single or double bushing capacitor commonly used on medium and high voltage capacitor banks. Use Table one when the capacitor voltage and kvar are known.  Use Table two when the system frequency and the capacitance of the capacitor are known. 

It should noted that in accordance with IEEE Std. 18-1992, capacitor units should not give less than 100% nor more than 115% (110% for capacitor units manufactured in conformance with IEEE Std 18-1992 after the year 2000) of rated reactive power at rated sinusoidal voltage and frequency, measured at a uniform case and internal temperature of 25C. Acutal values tend to be close to +2% of nominal.

Table 1 - Calculation of Capacitive Reactance (Xc) 

Known Variables: Frequency and Capacitance  





Input capacitance (Farads)
Input frequency at which capacitor will be operated (Hertz)
Capacitor Reactance (Ohms)

Table 2 - Calculation of Capacitive Reactance (Xc) 

Known Variables: Capacitor Voltage and kvar rating  





Input capacitor voltage (kv)
Input capacitor kvar rating (kvar)
Capacitor Reactance (Ohms)

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