ADE7761ARS-REF View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
ADE7761ARS-REF Datasheet PDF : 28 Pages
| |||
ADE7761
The ADE7761 leaves the missing neutral mode for normal
operation when both conditions are no longer valid—voltage
peak value greater than 9% of full scale and zero crossing on the
voltage channel detected (see Figure 32).
V2P
V2
V2N
AGND
ADC
MISSING
NEUTRAL
FILTER AND
THRESHOLD
where:
F1, F2 Frequency is the output frequency on F1 and F2 (Hz).
V1rms is the differential rms voltage signal on Channel 1 (V).
MISCALrms is the differential rms voltage signal on the MISCAL
pin (V).
VREF is the reference voltage (2.5 V ± 8%) (V).
F1-4 is one of four possible frequencies selected by using the
logic inputs S0 and S1 (see Table 5).
|V2|PEAK > 9% OF FULL SCALE
Example
AND
ZERO-CROSSING ON V2
In normal mode, ac voltages of ±330 mV peak are applied to V1
V2P–V2N
FS
+9% OF FS
–9% OF FS
E Figure 32. Return to Normal Mode after Missing Neutral Detection
T Missing Neutral Gain Calibration
When the ADE7761 is in missing neutral mode, the energy is
billed based on the active current input signal level. The
E calibration of the frequency outputs in this mode can be done
with the MISCAL analog input pin. In this mode, applying a dc
voltage of 330 mV on MISCAL is equivalent to applying, in
L normal mode, a pure sine wave on the voltage input with a peak
value of 330 mV. The MISCAL input can vary from 0 V to
660 mV (see the Analog Inputs section). When set to 0 V, the
frequency outputs are close to zero. When set to 660 mV dc, the
O frequency outputs are twice that when MISCAL is at 330 mV
dc. In other words, Equation 7 can be used in missing neutral
mode by replacing V2rms by MISCALrms √2:
OBS F1,F2
Frequency
=
5.70
×
MISCALrms
VREF 2
/
2 × F1−4
(8)
and V2, and then the expected output frequency on F1 and F2 is
calculated as follows:
F1–4 = 1.7 Hz, SCF = S1 = S0 = 0
V1 = rms of 330 mV peak ac = 0.33/√2 V
V2 = rms of 330 mV peak ac = 0.33/√2 V
VREF = 2.5 V (nominal reference value)
5.70×0.33×0.33×1.7 Hz
F1 , F2 Frequency =
2 × 2 ×2.52
= 0.084 Hz
CF Frequency = F1 − F2 frequency × 64 = 5.4 Hz
In missing neutral mode, ac voltage of ±330 mV peak is applied
to V1, no signal is connected on V2, and 330 mV dc input is
applied to MISCAL. With the ADE7761 in the same configura-
tion as the previous example, the expected output frequencies
on CF, F1, and F2 are
5.70 × 0.33× 0.33 / 2 ×1.7 Hz
F1 , F2 Frequency =
2 × 2.52
= 0.084 Hz
CF Frequency = F1 , F2 frequency × 64 = 5.4 Hz
Rev. A | Page 22 of 28
Share Link: 