Measurements; Current Channel Measurement Update Rates - Analog Devices ADE9000 Technical Reference Manual

ADE9000 Technical Reference Manual

MEASUREMENTS

CURRENT CHANNEL MEASUREMENT UPDATE
RATES
Table 5 indicates the registers that hold current channel
measurements and the rate at which they update.
Table 5. Current Channel Measurement Update Rates
Register
Name Description
AI_SINC_DAT IA sinc4 filter output
BI_SINC_DAT IB sinc4 filter output
CI_SINC_DAT IC sinc4 filter output
NI_SINC_DAT IN sinc4 filter output
AI_LPF_DAT IA sinc4 + IIR LPF filter output
BI_LPF_DAT IB sinc4 + IIR LPF filter output
CI_LPF_DAT IC sinc4 + IIR LPF filter output
NI_LPF_DAT IN sinc4 + IIR LPF filter output
AI_PCF Instantaneous current on IA
BI_PCF Instantaneous current on IB
CI_PCF Instantaneous current on IC
NI_PCF Instantaneous current on IN
AIRMS Filtered-based total rms of IA
BIRMS Filtered-based total rms of IB
CIRMS Filtered-based total rms of IC
NIRMS Filtered-based total rms of IN
ISUMRMS Filtered rms of vector sum (AI_PCF +
BI_PCF + CI_PCF ± NI_PCF); see the
Neutral Current RMS, Vector Current
Sum section
IPEAK Peak current channel sample; see the
Peak Detection section
ANGLx_xxx Voltage to current or current to
current phase angle; see the Angle
Measurement section
ADC_REDIRECT Multiplexer
The ADE9000 provides a multiplexer that allows any ADC
output to be redirected to any digital processing datapath.
By default, each modulator is mapped to its corresponding
datapath. For example, the IAP and IAN pins go into the IA
modulator, which is mapped to the IA digital processing
datapath. Write to the ADC_REDIRECT register to change the
ADC to digital channel mapping.
The redirection can be useful to simplify layout, depending on if
the ADE9000 is on the top or bottom of the PCB, by redirecting
the IA ADC output to the IC digital datapath and the IC ADC
output to the IA digital datapath. To redirect the IA and IC
ADC outputs, write IA_DIN = 010 and IC_DIN = 000 in the
ADC_REDIRECT register.
Alternatively, the VA voltage channel output can be used for all
three datapaths by writing VB_DIN = 101 and VC_DIN = 101
in the ADC_REDIRECT register.
The neutral current channel does not offer a zero-crossing output
or angle measurements. To calibrate the phase of the neutral
current NI_PCF signal, direct the neutral current ADC output
to, for example, the Phase B digital current channel and check
how its angles correspond to Phase A by writing IA_DIN = 111.
IA MODULATOR
Update
Rate
32 ksps
V
32 ksps IN
32 ksps
32 ksps
f = 8 ksps
DSP
f = 8 ksps
DSP
Figure 10. ADC_REDIRECT Modulator to Digital Datapath Multiplexing
f = 8 ksps
DSP
f = 8 ksps
Current Channel Gain, xIGAIN
DSP
f = 8 ksps
DSP
There are many sources of gain error in an energy metering
f = 8 ksps
DSP system. The current sensor, including current transformer
f = 8 ksps
DSP
burden resistors, may have some error. There is part to part gain
f = 8 ksps
DSP error in the
f = 8 ksps
DSP
may have some variation (see the data sheet for the device
f = 8 ksps
DSP specifications).
f = 8 ksps
DSP
The ADE9000
f = 8 ksps
DSP
that each metering device has the same current channel scaling.
f = 8 ksps
DSP
The current channel gain varies with xIGAIN as shown in the
following equation:
f = 8 ksps
DSP
Current
CLKIN/24 =
Use this equation to calculate the xIGAIN value for a given
1024 ksps
current channel gain:
xIGAIN = ROUND((Current Channel Gain − 1) × 2
The current channel gain can be positive or negative.
For example, to gain the current channel up by 10% to 1.1,
xIGAIN = ROUND((1.1 − 1) × 2
0x00CC_CCCD
To gain it down by 10% to 0.9,
xIGAIN = ROUND((0.9 − 1) × 2
0xFF33_3333
It is also possible to use the current channel gain register to
change the sign of the current channel, which can be useful if
the current sensor was installed backwards. To compensate for
this, use current channel gain = −1.
xIGAIN = ROUND((−1 − 1) × 2
0xF000_0000
If the multipoint phase and gain feature is used, it is recommended
to use the xIGAIN for the main correction, done at the nominal
current for the meter (see the Multipoint Phase/Gain Calibration
section for more information).
Rev. 0 | Page 9 of 86
IA_MOD
000
IB_MOD
REFERENCE
001
IC_MOD
010
IN_MOD
011
Σ-Δ
VA_MOD
MODULATOR
100
VB_MOD
101
VC_MOD
110
IA_MOD
111
IA_DIN[2:0]
ADE9000 device itself, and the voltage reference
provides a current gain calibration register so
xIGAIN
 +
=
Channel Gain 1


UG-1098
IA DIGITAL DATAPATH
AI_SINC_DAT AI_LPF_DAT


27
2 
27
= 13421773 =
27
= −1 × 10 =
27 7
27 = −268435456 =