ADE7761A
TERMINOLOGY
Measurement Error
The error associated with the energy measurement made by the
ADE7761A is defined by
Percentage Error
=
⎛
Energy registered by ADE7761A
−
True Energy
⎞
⎜
×
100%
⎟
⎜
⎟
True Energy
⎝
⎠
Phase Error Between Channels
The high-pass filter (HPF) in the current channel has a phase
lead response. To offset this phase response and equalize the
phase response among channels, a phase correction network is
also placed in the current channel. The phase correction network
ensures a phase match between the current channels and
voltage channels to within ±0.1° over a range of 45 Hz to
65 Hz and ±0.2° over a range of 40 Hz to 1 kHz.
Power Supply Rejection (PSR)
PSR quantifies the ADE7761A measurement error as a
percentage of reading when the power supplies are varied. For
the ac PSR measurement, a reading at nominal supplies (5 V) is
taken. A second reading is obtained with the same input signal
levels when an ac (175 mV rms/100 Hz) signal is introduced
onto the supplies. Any error introduced by this ac signal is
expressed as a percentage of reading (see the Measurement
For the dc PSR measurement, a reading at nominal supplies
(5 V) is taken. A second reading is obtained with the same input
signal levels when the power supplies are varied ±5%. Any error
introduced is again expressed as a percentage of reading.
ADC Offset Error
The dc offset associated with the analog inputs to the ADCs.
With the analog inputs connected to AGND, the ADCs still see
a dc analog input signal. The magnitude of the offset depends on
the input gain and range selection (see the Typical Performance
the offset is removed from the current channels and the power
calculation is not affected by this offset.
Gain Error
The gain error in the ADE7761A ADCs is defined as the
difference between the measured output frequency (minus the
offset) and the ideal output frequency. It is measured with a
gain of 1 in Channel V
1A
. The difference is expressed as a
percentage of the ideal frequency, which is obtained from the
transfer function (see the Transfer Function section).
Gain Error Match
The gain error match is defined as the gain error (minus the
offset) obtained when switching between a gain of 1 or 16. It is
expressed as a percentage of the output ADC code obtained
under a gain of 1.
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