ADE7763: Irms

Document created by analog-archivist Employee on Feb 23, 2016
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I am evaluating ADE7763 for a new application.

I want to know detailed specification reagrding IRMS Measurement Error:
* in function of frequency
* in function of temperature
* min & max

Application note specify only typical IRMS Measurement Error
(0.5 % typ Over a dynamic range 100 to 1)
I don't understand why:
    Active Power Measurement Error is only 0.1 % typ over a dynamic range 1000
to 1
    when calculated from IRMS & VRMS each with 0.5 % typ error ?!


I'm afraid that we don't have the detailed specifications of the Irms
Measurement error that you ask for. The specifications marked on the datasheet
are those which have been tested, either in production or in pre-release
qualification of the design. The ADE7763 needs to be calibrated in the context
of the full measurement signal chain (sensors etc).  Note also the comments on
page 20, at the end of the section describing the ADE7763 reference: drift of
the internal reference will mean that one can only obtain guaranteed
temperature performance if an external reference is used.

Active power is calculated separately from Irms and Vrms. The Active power
measurement signal chain is shown in figure 55 of the datasheet on page 26. The
individual samples from the voltage and current channels are multiplied to give
the instantaneous power

p(t) = v(t)*i(t)

P = 1/nT * s {0..nT} [p(t)]dt

This is the relation used to calculate the average power in the ADE7763 and it
allows excellent precision over a wide dynamic range.

The VRMS and IRMS values are calculated by a separate signal chain so there is
no contradiction of Irms and Vrms error of 0.5% and an active power error of