AC Resistance Measurement Explanation

Understanding Resistance Measurement in AC Circuits

Introduction

This page explains why measuring current from only one wire in an AC circuit can lead to incorrect resistance and power calculations.

We'll explore the math and provide a basic calculator to demonstrate these differences.

Key Formulas

Ohm's Law: R = V / I
Total Current: I_total = V / R
Power: P = V * I
Per Wire Current (Balanced Split): I_per_wire = I_total / 2

Example Setup

We use the following setup for calculations:

Load Resistance: 1 Ω
Amplifier Voltage (RMS): 40 V
Total Current: \( I_total = 40 A \)
Balanced Split: Each wire carries 20 A.

Comparison Table

Measurement Setup	Voltage (V)	Current (I)	Resistance (R)	Power (P)
Both Positives Clamped	40 V	40 A	1 Ω	1600 W
One Positive Clamped	40 V	20 A	2 Ω	800 W

Basic Calculators

Calculator 1: Enter values below to calculate resistance and power:

Voltage (V):
Measured Current (I):

Results:

Resistance: N/A
Power: N/A

Calculator 2: Enter values below to calculate resistance and power:

Voltage (V):
Measured Current (I):

Results:

Resistance: N/A
Power: N/A

Click Here For More Details & Data