Introductory Electrical Engineering With Math Explained in Accessible Language

22Norton’s Theorem: Circuit Analysis

22.1 Introduction

In this chapter, we will examine Norton’s theorem, also known as Mayer’s theorem, developed at the same time, in 1926, by Hans Ferdinand Mayer, researcher of Siemens & Halske in Germany, and by Edward Lawry Norton, engineer and researcher of the legendary Bell Labs¹ in the United States.

22.2 Norton’s Theorem

Following the idea of Thévenin’s theorem, Norton’s theorem proposes the replacement of complex circuits with an equivalent simplified version, known as Norton equivalent circuit.

Figure 22.1 Norton equivalent circuit.

Thévenin theorem replaces the original circuit with a voltage source in series with a resistor. Norton’s theorem, however, replaces the original circuit with a current source in parallel with a resistor, like shown in Figure 22.1.

22.2.1 Finding Norton Equivalent Circuit

Like Thévenin, Norton equivalent circuit is always equivalent to two chosen points in a circuit, like the input, the output, etc. Different points in a circuit will generate different Norton circuits.

22.2.2 Methodology

These rules must be followed to obtain the Norton equivalent circuit:

• Create a new circuit version where the load is short‐circuited, and calculate the current source using nodal analysis and Kirchhoff’s current law (KCL).
• Create a new circuit version without the load, without all current sources, and with all ...