EVAL-ADE7816EBZ AD [Analog Devices], EVAL-ADE7816EBZ Datasheet - Page 21

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

Data Sheet
The content of the active energy register overflows from full-scale
positive (0x7FFFFFFF) to full-scale negative (0x80000000) and
continues to increase in value when the active power is positive.
Conversely, if the active power is negative, the energy register
underflows from full-scale negative (0x80000000) to full-scale
positive (0x7FFFFFFF) and continues decreasing in value. Bit 0
(AEHF1) in the STATUS0 register (Address 0xE502) is set when
Bit 30 in the AWATTHR, BWATTHR, or CWATTHR register
changes, signifying that one of these registers is half full. Simi-
larly, Bit 1 (AEHF2) in the STATUS0 register is set when Bit 30
in the DWATTHR, EWATTHR, or FWATTHR register changes,
signifying that one of these registers is half full.
Setting Bit 6 (RSTREAD) in the LCYCMODE register
(Address 0xE702) enables a read-with-reset for all watt-hour
accumulation registers. When this bit is set, all energy accu-
mulation registers are set to 0 following a read operation.
REACTIVE ENERGY MEASUREMENT
Definition of Reactive Power and Reactive Energy
Reactive power is the product of the voltage and current when all
harmonic components of one of these signals are phase shifted
by 90°. Reactive power is the power dissipated in an induc-tive or
capacitive load and is measured as volt-ampere reactive (var).
Reactive energy is the accumulation of reactive power over time.
where:
V is the rms voltage.
I is the rms current.
RP is the reactive or real power.
T is the line cycle period.
Reactive Energy Registers
The
active energy for each of the six channels separately: AVARHR
(Address 0xE406), BVARHR (Address 0xE407), CVARHR
(Address 0xE408), DVARHR (Address 0xE409), EVARHR
(Address 0xE40A), and FVARHR (Address 0xE40B). All
reactive energy registers are in 32-bit, signed format. The
ADE7816
power. Negative reactive power indicates that the current
is leading the voltage by up to 180°. The
a signed accumulation of the power, where positive power
is added and negative is subtracted.
ADE7816
RP =
VA
IA
PCF_A_COEFF
accumulates both positive and negative reactive
nT
1
nT
∫
0
has six reactive energy registers that accumulate
RP
( )
t
IAGAIN
VGAIN
dt
= VI × sin(θ)
HPF
HPF
INTEGRATOR
ADE7816
DIGITAL
provides
ALGORITHM
REACTIVE
Figure 29. Reactive Energy Signal Path
POWER
TOTAL
Rev. 0 | Page 21 of 48
(3)
AVAROS
AVARGAIN
Reactive Energy Threshold
The
is done internally using the threshold registers, VARTHR1
(Address 0x43AD) and VARTHR0 (Address 0x43AE). These
registers make up the most significant and least significant 24 bits,
respectively, of an internal threshold register that is used to control
the frequency at which the external xVARHR registers are updated.
The VARTHR1 and VARTHR0 registers affect all six reactive
energy measurements. For standard operation, the VARTHR1
register should be set to 0x2 and the VARTHR0 register set to
0x0. This sets the update rate of the xVARHR registers to the
maximum of 8 kHz with full-scale inputs.
If the rate at which energy is accumulated in the xVARHR
registers must be reduced, VARTHR1 and VARTHR0 can be
modified as follows:
Note that the maximum output with full scale inputs is 8 kHz.
The threshold should not be adjusted to try to produce more
than 8 kHz. Such an adjustment could result in saturation of the
output frequency and, therefore, a loss of accuracy.
The second stage of the accumulation is done in the external
registers, xVARHR. With the recommended values provided in
Equation 4, the reactive energy updates at a rate of 8 kHz with
full-scale inputs (see Figure 29).
Reactive Energy Accumulation and Register Roll-Over
The reactive energy accumulates at a maximum rate of 8 kHz
with full-scale inputs. The maximum positive value that the 32-bit,
signed xVARHR registers can store before they overflow is
0x7FFFFFFF. Assuming steady accumulation with full-scale
reactive energy inputs, the accumulation time is
Conversely, if the reactive power is negative, the energy register
underflows from full-scale negative (0x80000000) to full-scale
positive (0x7FFFFFFF) and continues decreasing in value. Bit 2
(REHF1) in the STATUS0 register is set when Bit 30 of the
AVARHR, BVARHR, or CVARHR register changes, signifying
that one of these registers is half full. Similarly, Bit 3 (REHF2)
in the STATUS0 register is set when Bit 30 of the DVARHR,
EVARHR, or FVARHR register changes, signifying that one
of these registers is half full.
ADE7816
Threshold = 0x2000000 ×
Time = 0x7FFFFFFF × 125 μs = 74 hr, 33 min, 55 sec
ACCUMULATOR
accumulates energy in two steps. The first
VARTHR[47:0]
Required
Update
8
AVARHR[31:0]
kHz
REGISTER
32-BIT
Rate
ADE7816
(kHz)
(4)