ADE7752B Datasheet, PDF (21/27 Pages) Analog Devices – Polyphase Energy Metering IC with Pulsed Output

Preliminary Technical Data
POWER MEASUREMENT CONSIDERATIONS
Calculating and displaying power information always have some
associated ripple that depends on the integration period used in the
MCU to determine average power as well as the load. For example,
at light loads, the output frequency can be 10 Hz. With an integra-
tion period of two seconds, only about 20 pulses are counted. The
possibility of missing one pulse always exists since the ADE7752B
output frequency is running asynchronously to the MCU timer.
This would result in a 1-in-20 or 5% error in the power measure-
ment. To remedy this, an appropriate integration time should be
considered to achieve the desired accuracy.
ADE7752B
MODE SELECTION OF THE SUM OF THE THREE
ACTIVE ENERGIES
The ADE7752B can be configured to execute the arithmetic
sum of the three active energies, Wh = Wh_ΦA + Wh_ΦB + Wh_ΦC,
or the sum of the absolute value of these energies, Wh = |Wh_ΦA|
+ |Wh_ΦB| + |Wh_ΦC|. The selection between the two modes can
be made by setting the ABS pin. Logic high and logic low
applied on the ABS pin correspond to the arithmetic sum and
the sum of absolute values, respectively.
When the sum of the absolute values is selected, the active
energy from each phase is always counted positive in the total
active energy. It is particularly useful in 3-phase 4-wire
instillation where the sign of the active power should always be
the same. If the meter is misconnected to the power lines, that
is, CT connected in the wrong direction then the total active
energy recorded without this solution can be reduced by two-
thirds.
The sum of the absolute values assures that the active energy
recorded represents the actual active energy delivered.
Regardless of the mode selected using this pin, the reverse
power pin still detects when negative power is present on the
sum of the three phase inputs.
Rev. PrA | Page 21 of 27