Capacity Susceptance

Original Form To Preserve

Steinmetz identifies C as electrostatic capacity and gives capacity susceptance as:

b = 2\pi f C

Modern Notation

B_C = \omega C

B_C = 2\pi f C

Relation To Reactance

For a pure capacitance:

X_C = \frac{1}{\omega C}

while capacitive susceptance is:

B_C = \omega C

They are reciprocal in the pure case, but in a general complex circuit one must take the reciprocal of the whole impedance, not just one component.

Worked Example

If:

f = 60\ \mathrm{Hz},\quad C = 10\ \mu\mathrm{F}

then:

B_C = 2\pi(60)(10 \times 10^{-6}) \approx 0.00377\ \mathrm{S}

and the corresponding pure-capacitive reactance magnitude is:

X_C = \frac{1}{B_C} \approx 265\ \Omega

Physical Meaning

Susceptance tells how much quadrature current a dielectric or condenser draws per volt. It is field storage seen from the admittance side of the calculation.

Electrostatic Capacity
Susceptance
Dielectric Loss