How do you calculate Copper Loss?

Copper loss, or I²R loss, refers to the power loss caused by the resistance of copper windings in the electrical equipment such as

Transformers,

Motors, and

Generators.

Copper Loss Formula

It is calculated using the following formula:

Copper loss = I2 x R

Where,

I - Current flowing through conductor (A), and

R - Conductor’s Resistance (in ohms).

Steps for Calculating Copper Loss

Step-1: Measure or get the current that flows through the copper winding.

Step-2: Measure the resistance (R) of the copper winding. This can be measured using an ohmmeter or estimated using copper’s length, cross-sectional area, and resistivity.

Step-3: To calculate copper loss, use the following formula and substitute current and resistance values.

Solved Example

Consider a transformer winding with resistance of 0.5Ω & a current of 10 amps flowing through it.

Current (I): 10A.

Resistance (R): 0.5 Ω.

Copper loss = 10 x 10 x 0.5

Copper loss = 100 x 0.5.

Copper loss = 50 watts.

Thus, the copper loss is 50W

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