sus·cep·tance  (s-sptns)

n. Electronics

The imaginary part of the complex representation of admittance.

Susceptance (symbolized B ) is an expression of the ease with which alternating current ( AC) passes through a capacitance or inductance .

http://whatis.techtarget.com/definition/susceptance

susceptance

DEFINITION

In some respects, susceptance is like an AC counterpart of direct current ( DC ) conductance . But the two phenomena are different in important ways, and they can vary independently of each other. Conductance and susceptance combine to form admittance , which is defined in terms of two-dimensional quantities known as complex number s.

When AC passes through a component that contains a finite, nonzero susceptance, energy is alternately stored in, and released from, a magnetic field or an electric field. In the case of a magnetic field, the susceptance is inductive. In the case of an electric field, the susceptance is capacitive. Inductive susceptance is assigned negative imaginary number values, and capacitive susceptance is assigned positive imaginary number values.

As the inductance of a component increases, its susceptance becomes smaller negatively (that is, it approaches zero from the negative side) in imaginary terms, assuming the frequency is held constant. As the frequency increases for a given value of inductance, the same thing happens. If L is the inductance in henries ( H ) and f is the frequency in hertz ( Hz), then the susceptance - jB _L , in imaginary-number siemens , is given by:

- jB _L = - j (6.2832 fL ) ^-1

where 6.2832 is approximately equal to 2 times pi , a constant representing the number ofradian s in a full AC cycle, and j represents the unit imaginary number (the positive square root of -1).

As the capacitance of a component increases, its susceptance becomes larger positively in imaginary terms, assuming the frequency is held constant. As the frequency increases for a given value of capacitance, the same thing happens. If C is the capacitance in farads ( F ) and f is the frequency in Hz, then the susceptance +jB _C , in imaginary-number ohms, is given by:

+jX _C = + j (6.2832 fC )

http://en.wikipedia.org/wiki/Susceptance

Susceptance

From Wikipedia, the free encyclopedia

In electrical engineering, susceptance (B) is the imaginary part of admittance. The inverse of admittance is impedance and the real part of admittance is conductance. In SI units, susceptance is measured in siemens. Oliver Heaviside first defined this property, which he called permittance, in June 1887^{[citation needed]}.

[edit]Formula

The general equation defining admittance is given by

where

Y is the admittance, measured in siemens (a.k.a. mho, the inverse of ohm).

G is the conductance, measured in siemens.

j is the imaginary unit, and

B is the susceptance, measured in siemens.

Rearranging yields

.

But since

,

we obtain

.

The admittance (Y) is the inverse of the impedance (Z)

or

where

Z is the impedance, measured in ohms

R is the resistance, measured in ohms

X is the reactance, measured in ohms.

Note: The susceptance is the imaginary part of the admittance.

The magnitude of admittance is given by: