Conductance, Susceptance & Admittance | Explained

• June 10, 2020
• Gaurav J

Conductance, Susceptance & Admittance are few terms which most of the engineers ignores. Because, they sounds difficult or we think they are not importance. But, it is imporant to know about these terms in order to make our basics clear. And yes, believe me I can give you the easiest explanation of these terms and to get that you need to watch the video.

Black X White
True X False
Happy X Unhappy

You guys might be thinking what is going on? Well, we saw some words which are completely opposite to each other. Black is opposite to white. similarly, true is opposite to false and so on. And what we are going to see today in this tutorial is the same. We are going to see few opposite terms in Electrical Engineering. Don’t worry, You’ll understand what I am saying just keep reading.

To understand the concept of Conductance, Susceptance & Admittance, it is important to know first about Resistance, Reactance & Impedance, as it will help to understand things easily.

Conductance

We know about resistance. In simple words, Resistance is opposition offered to the flow of electrons. Now there is a term which is exactly opposite to the resistance, and it is known as, ‘simplicity offered to the flow of electrons’. And this term in one word is known as “Conductance”.

Simplicity offered to the flow of electrons is known as Conductance

We know that, the term ‘Resistance’ denotes the opposition to the flowing electrons in a circuit. On the other hand, ‘Conductance’ represents the ease or easiness offered to the flow of electrons. Resistance represent how much a circuit resist current, conductance represents how much a circuit conducts current.

Unit of conductance is “MHOS” or simply ohms spelled backward. “Siemens” is also used as a unit of conductance many times. Letter “G” is used to denote the Conductance.

Mathematically conductance is given by,
G = 1/R

In parallel circuits resistance diminishes but the conductance adds.

Susceptance

Now, let’s talk about Susceptance. AS we know, the opposition offered by capacitors and inductors is a bit different than resistance. Therefore, we call it as “Reactance”. We measure it in Ohms.

Like, true has false, resistance has conductance, and reactance has “Susceptance”. Susceptance is exactly opposite to reactance. Reciprocal of reactance is susceptance. So, it is given by 1/X. It is denoted by letter ‘B’ and measured in ‘mhos’ or ‘Siemens’. Reactance is the measure of how much circuit reacts against change in current over time. On the other hand, Susceptance represents how much circuit is susceptible to conducting a changing current or simply, how much circuit allows the changing current. Like Conductance, Susceptance also adds in parallel and diminish in series.

Susceptance represents how much circuit is susceptible to conducting a changing current or simply how much circuit allows the changing current.

Admittance

Now, let’s understand admittance. Circuit consisting of both i.e. resistor and inductor will offer both the types of oppositions i.e. Resistance and Reactance. Therefore, We cannot call this kind of opposition neither resistance nor reactance. So, we need more suitable term for this kind of opposition and the term is known as “Impedance”.

Like, True has false; resistance has conductance; Reactance has Susceptance, similarly we have “Admittance” for Impedance. Impedance is measure of how much alternating current is impeded or avoided in the circuit, while Admittance is a measure of how much alternating current is Admitted or allowed in the circuit. Like Conductance and Susceptance it is also measured is Siemens and it is denoted by letter “Y”.

Admittance is a measure of how much alternating current is Admitted or allowed in the circuit.

So, how to remember these terms? It can be tricky but it’s easy, believe me. Just remember the opposite words.

Black X White
Resistance X Conductance

True X False
Reactance X Susceptance

Happy X Unhappy
Impedance X Admittance