Power calculator

What the calculation is

There is only one equation behind it.

P ≈ 2πf · C · V² · tanδ

Power scales with the drive frequency f and with the square of the drive voltage V. So a figure quoted as P₀ at a measurement frequency f₀ works out to P₀ × (f / f₀) at frequency f. If you fill in the voltage fields, the result is multiplied by (V / V₀)² as well. The reasoning is set out in why the power draw of switchable film depends on drive frequency.

⚠ What this assumes

The numbers above are estimates derived from that equation, not values we have measured. They rest on the following assumptions.

• tanδ (the loss tangent) is taken to be constant with frequency. In practice tanδ does shift somewhat with frequency, so the further the comparison frequency sits from the measured point, the larger the departure is likely to be
• It holds only while the drive voltage still reaches the whole sheet. Raise the frequency far enough and the resistance of the transparent electrode, together with the capacitance of the film, keeps the voltage from reaching the far side. Past that point the proportionality no longer applies
• With the voltage fields left blank, both films are assumed to be driven at the same voltage. When the two have different switching voltages, enter the actual drive voltage for each
• Whether a figure covers the film alone or includes the power supply and controller depends on the figure you entered. If one includes them and the other does not, converting the frequency will not make them comparable

Where a project needs the figure confirmed on real hardware, our evaluation kit is available.

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