EVAL-ADE7816EBZ AD [Analog Devices], EVAL-ADE7816EBZ Datasheet - Page 26

• Manufacturer Part Number: EVAL-ADE7816EBZ
• Description: Six Current Channels, One Voltage Channel
• Manufacturer: AD [Analog Devices]

ADE7816
POWER QUALITY FEATURES
This section describes the power quality features that are available
in the ADE7816.
SELECTING A CURRENT CHANNEL GROUP
When using the power quality features on the current channels,
the group of channels to be monitored must be selected. Bit 14
(CHANNEL_SEL) of the COMPMODE register (Address 0xE60E)
can be used to make this selection. To select the A, B, and C current
channels for the current channel power quality measurements,
CHANNEL_SEL must be set to 0 (default). To select the D, E,
and F current channels for the current channel power quality
measurements, CHANNEL_SEL must be set to 1. If all channels
require monitoring, the monitoring must be done in series by
modifying the CHANNEL_SEL bit after data is obtained. The
settling time of each power quality measurement is provided in
the section that pertains to each power quality feature.
INSTANTANEOUS WAVEFORMS
The
waveform data. This information allows the instantaneous data
to be analyzed in more detail, including reconstruction of the
current and voltage input for harmonic analyses. These measure-
ments are available from a set of 24-bit, signed registers. The
voltage channel has a dedicated register, VWV (Address 0xE510),
whereas the current channels share three registers: IAWV/IDWV
(Address 0xE50C), IBWV/IEWV (Address 0xE50D), and ICWV/
IFWV (Address 0xE50E). A group of current channels (A, B, C
or D, E, F) must be selected by Bit 14 (CHANNEL_SEL) of the
COMPMODE register (see the Selecting a Current Channel
Group section).
All measurements are updated at a rate of 8 kHz. The
provides an interrupt status bit, DREADY (Bit 17 of the STATUS0
register, Address 0xE502), that is triggered at a rate of 8 kHz,
allowing measurements to be synchronized with the instanta-
neous update signal rate. The instantaneous update signal can
ADE7816
provides access to the current and voltage channel
ID, IE, IF, OR V
IA, IB, IC,
PGA
REFERENCE
ADC
ADE7816
ID, IE, IF, OR V
Figure 33. Zero-Crossing Detection
IA, IB, IC,
Rev. 0 | Page 26 of 48
IxGAIN OR
0.855
VGAIN
0V
1
ZX
also be configured to trigger an interrupt on the external pin
by setting the DREADY bit (Bit 17) in the MASK0 register
(Address 0xE50A). With the specified full-scale analog input
signal of 0.5 V, the expected reading on the current and voltage
waveform register is approximately ±5,989,256 (dec).
The instantaneous waveforms have no additional settling time,
and, therefore, if the CHANNEL_SEL bit is modified to change
the group of current channels being measured, the new result is
available in 125 μs (8 kHz).
ZERO-CROSSING DETECTION
Zero-Crossing Detection
The
voltage and current channels. Zero-crossing detection allows
measurements to be synchronized to the frequency of the
incoming waveforms.
The zero-crossing events are filtered internally by an LPF. The
LPF is intended to eliminate all harmonics of 50 Hz and 60 Hz
systems, and to help identify the zero-crossing events on the
fundamental components of both current and voltage channels.
The digital filter has a pole at 80 Hz and is clocked at 256 kHz.
As a result, there is a phase lag between the analog input signal
and the output of the LPF. The error in ZX detection is 0.0703°
for 50 Hz systems and 0.0843° for 60 Hz systems. The phase lag
response of the LPF results in a time delay of approximately
31.4° or 1.74 ms (at 50 Hz) between its input and output. The
overall delay between the zero crossing on the analog inputs and
the ZX detection that is obtained after LPF1 is about 39.6° or
2.2 ms (at 50 Hz). Figure 33 shows how the zero-crossing signal
is detected.
To provide further protection from noise, input signals to the
voltage channel with an amplitude of <10% of full scale do not
generate zero-crossing events at all. The ZX detection circuit of
the current channels is active for all input signals, independent
of their amplitudes.
39.6° OR 2.2ms @ 50Hz
HPF
ZX
ADE7816
ZX
LPF_ZX
LPF_ZX OUTPUT
has a zero-crossing (ZX) detection circuit on the
ZX
ZX
DETECTION
Data Sheet