What is susceptance? - Definition from WhatIs.com
Part of the Smart grid glossary:

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

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 of radian 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 )

Also see admittance , conductance , reactance , resistance , impedance , ohm , siemens , henry , and farad .

This was last updated in March 2010
Posted by: Margaret Rouse

Related Terms


  • WRAN (wireless regional area network)

    - A wireless regional area network (WRAN) is techology based on IEEE 802.22 to take advantage of underused white space spectrum and bring high-speed wireless connectivity to rural areas. (WhatIs.com)

  • event-condition-action rule (ECA rule)

    - An event condition action rule (ECA rule) is the underlying model for event-driven programming, in which actions are triggered by events, given the existence of specific conditions. (WhatIs.com)

  • FBI Alert Number I-091015-PSA

    - FBI Alert Number I-091015-PSA is a public service announcement from the United States Federal Bureau of Investigation to inform individuals and organizations about the importance of Internet of Thi... (WhatIs.com)


  • Smart grid

    - Terms related to smart grids, including definitions about utility electricity delivery systems and words and phrases about smart meters and distributing, monitoring and billing electrical power.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question. Find an Answer.Powered by ITKnowledgeExchange.com

Ask An IT Question

Get answers from your peers on your most technical challenges

Ask Question
  • How do I generate a secure token for a mobile app to protect its data?

    Hi,The "validation token" works by how the server recalls it.A general token is a random string; the server keeps in its database a mapping from emitted tokens to authenticated user names. Old toke...

  • Could a honeypot machine risk the secure network?

    Honeypots in general always seem to create 2 lines of thought. Are they a good thing or a bad thing? Your intention of using it to see what potential threats are nearby whilst not a bad idea has a ...

  • DX2390 and Networking

    If these are new, then you should be able to get support directly from HP on this issue. I would also apply latest firmware/bios updates and any other updates from the manufacturer that might addre...

Tech TalkComment



    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.