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I have a component on a board which calculate the active power and reactive power. The component first mesure the voltage, the intensity and the phase then calculate the powers with:

P = U * I * cos(phy)

Q = U * I * sin(phy)

I know the whole chain of voltage measurement (filter, transformer, ADC) has an accuracy of 0,6%. I know the whole chain of intensity measurement (filter, transformer, ADC) has an accuracy of 0,9%. I know the whole chain of phase measurement (filter, transformer, ADC) has an accuracy of 5,9°.

I need to do it for a general measure, I mean i can't use the partial derivative method because I don't have the value of U,I and phy.

Is there any way to calculate it?

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You know P and Q, hence you can determine phi and U*I. Now use actual maximum deviations to find the absolute errors and select +/- worst cases

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  • \$\begingroup\$ I'm sorry I don't get your answer, I have no value neither on P, Q , phy, U or I. I need to find the theorical erro \$\endgroup\$ – damien Apr 8 '16 at 11:00
  • \$\begingroup\$ Aren't P and Q available as measurements? That's all you need to estimate error bands. \$\endgroup\$ – Chu Apr 8 '16 at 11:11
  • \$\begingroup\$ No they are not, I do not have the board yet, i have to do the calculation while i'm designing the board to proove that the error i will mesure will be less than 5% \$\endgroup\$ – damien Apr 13 '16 at 14:38

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