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Armature Resistance Calculator

Formula

The formula to calculate the Armature Resistance is:

$Ra = \frac{V - E}{Ia}$

Where:

$Ra$ is the armature resistance (ohms)
$V$ is the voltage (volts)
$E$ is the back e.m.f (volts)
$Ia$ is the armature current (amps)

What is Armature Resistance?

An armature resistance is the total resistance seen in a motor with an armature current, voltage, and back e.m.f. It is calculated by subtracting the back e.m.f from the voltage and then dividing by the armature current.

Example Calculation 1

Let's assume the following values:

Voltage (V) = 24 volts
Back E.M.F (E) = 20 volts
Armature Current (Ia) = 2 amps

Using the formula:

$Ra = \frac{24 - 20}{2} = \frac{4}{2} = 2 \, \text{ohms}$

The Armature Resistance is 2 ohms.

Example Calculation 2

Let's assume the following values:

Voltage (V) = 36 volts
Back E.M.F (E) = 30 volts
Armature Current (Ia) = 3 amps

Using the formula:

$Ra = \frac{36 - 30}{3} = \frac{6}{3} = 2 \, \text{ohms}$

The Armature Resistance is 2 ohms.