ADE7761ARS-REF View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
ADE7761ARS-REF Datasheet PDF : 28 Pages
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ADE7761
RF
V1A
CT
IB
Important Note for Billing of Active Energy
The ADE7761 provides pulse outputs—CF, F1, and F2—
240V RMS
POWER
GENERATOR
RB V1A CF
intended to be used for the billing of active energy. Pulses are
generated at these outputs in two different situations.
0V
RB
V1N
CF
Case 1: When the analog input V2P – V2N complies with the
conditions described in Figure 32, CF, F1, and F2 frequencies
CT
RF
V1B
are proportional to active power and can be used to bill active
LOAD
RA*
energy.
RB*
CF
V2P
Case 2: When the analog input V2P – V2N does not comply with
VR*
RF
V2N
CT
*RB + VR = RF
Figure 29. Missing Neutral System Diagram
E The ADE7761 detects a missing neutral condition by continu-
ously monitoring the voltage channel input (V2P–V2N). The
FAULT pin is held high when a missing neutral condition is
T detected. In this mode, the ADE7761 continues to bill the
energy based on the signal level on the current channel (see
Figure 30). The billing rate or frequency outputs can be adjusted
by changing the dc level on the MISCAL pin.
E V1A
ADC
A>B
V1N
HPF
L ADC
V1B
B>A
ZERO
B <> A
CROSSING
DETECTION
LPF
O MISCAL
ADC
MISSING NEUTRAL
GAIN ADJUSMENT
DIGITAL-
TO-
FREQUENCY
CONVERTERS
CF F1 F2
OBS Figure 30. Energy Calculation in Missing Neutral Mode
the conditions described in Figure 32, the ADE7761 does not
measure active energy, but a quantity proportional to kAh. This
quantity is used to generate pulses on the same CF, F1, and F2.
This situation is indicated when the FAULT pin is high.
Analog Devices Inc. cautions users of the ADE7761:
• Billing active energy in Case 1 is consistent with the
understanding of the quantity represented by pulses on
CF, F1, and F2 outputs (watt-hour).
• Billing active energy while the ADE7761 is in Case 2 must
be decided knowing that the entity measured by the
ADE7761 in this case is ampere-hour and not watt-hour.
Users should be aware of this limitation and decide if the
ADE7761 is appropriate for their application.
Missing Neutral Detection
The ADE7761 continuously monitors the voltage input and
detects a missing neutral condition when the voltage input peak
value is smaller than 9% of the analog full scale or when no zero
crossings are detected on this input (see Figure 31).
V2P
V2
V2N
AGND
ADC
MISSING
NEUTRAL
FILTER AND
THRESHOLD
|V2|PEAK < 9% OF FULL SCALE OR NO ZERO-CROSSING ON V2
V2P–V2N
FS
V2P–V2N
FS
V2P–V2N
FS
9% OF FS
0V
0V
0V
Figure 31. Missing Neutral Detection
Rev. A | Page 21 of 28
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