Transformers and Power Supplies
Transformer Copper Loss Calculator
This calculator evaluates copper loss for a single transformers and power supplies scenario. It uses winding current and winding resistance and shows the equation behind the displayed value.
Enter values for Copper loss
Check the source and units before calculating.
Input notes
Identify RMS, average, peak, and rectified quantities explicitly. Do not combine a worst-case value with unrelated nominal data.
A prefix error can move the result by several orders of magnitude. The broader analysis may also use Contact Resistance Loss Calculator.
- Winding current
- Default example: 10 A. Enter winding current in A.
- Winding resistance
- Default example: 0.18 Ω. Enter winding resistance in Ω.
Copper loss: calculation method
The displayed result follows loss = I²R. Only Winding current and Winding resistance enter the numerical result.
The initial scenario returns 18.00 W. Re-enter field data before using the answer in a design or comparison.
Calculate copper loss from winding current and winding resistance. For the companion core loss calculation, open Transformer Core Loss Calculator.
Changing Winding current
Change Winding current from 10 A to 12 A without altering the remaining fields. The calculated value shifts from 18.00 W to 25.92 W.
Do not average the two cases if either could define an operating limit.
Reading Copper loss
The calculated Copper loss is meaningful only with its input conditions attached. Compare it with voltage stress, current stress, ripple, loss, regulation, and temperature.
Label alternate cases rather than overwriting the baseline.
What the formula leaves out
Winding resistance rises as the transformer warms.
Additional checks may be needed for isolation, creepage, waveform shape, and manufacturer operating limits. Resolve material omissions before selecting a standard size or rating.
Use voltage and current values from the same side of the transformer or converter.
Questions about Transformer Copper Loss
Which source values should I use for Copper loss?
Measured and rated values can represent different states. Identify RMS, average, peak, and rectified quantities explicitly.
What is not captured by this equation?
Winding resistance rises as the transformer warms. Also consider diode loss, ESR, regulation, ripple current, and thermal resistance.
Why might a second instrument give another answer?
Differences can come from diode loss, ESR, regulation, ripple current, and thermal resistance, measurement uncertainty, or values taken under different conditions.
What should remain fixed in an alternate case?
Keep unaffected entries fixed so the cause of the difference remains visible. Record waveform, frequency, load level, and winding or device temperature.
Can I select equipment from this number alone?
Use the number as one check, then review component ratings and isolation requirements.