UG-1098
ADE9000 Technical Reference Manual
Rev. 0 | Page 52 of 86
POWER CALIBRATION
APGAIN is the gain calibration register for Phase A. The active,
reactive, and apparent powers in each phase have a common
gain register and individual offset calibration registers.
1.
Apply the nominal voltage and current at power factor = 1.
2.
EP_CFG = 0x0011 and EGY_TIME = 7999 (1 sec
accumulation).
3.
Read the AWATTHR_HI register.
4.
The APGAIN register value is obtained as follows:
27
2
_
_
_
×
−
=
MEASURED
MEASURED
EXPECTED
HI
AWATTHR
HI
AWATTHR
HI
AWATTHR
APGAIN
AWATTHR_HI
EXPECTED
=
I
FSP
×
V
FSP
×
Full-Scale Power Codes
×
Accumulation Time
× 8000 × 2
−13
= 0.0947 × 0.311 × 20,694,066 × 1 sec × 8000 × 2
−13
= 595,191
Let AWATTHR_HI
MEASURED
= 580,000:
0x35A3D3
3515347
2
000
,
580
000
,
580
595,191
27
=
=
×
−
=
APGAIN
Like the rms offset calibration, the power offset calibration is
performed with a small current at 5000:1 or less dynamic range.
In this example, the offset calibration current is 20 mA and the
voltage is 220 V.
1.
Apply a nominal voltage and offset calibration current at
power factor = 1.
2.
EP_CFG = 0x0013 and EGY_TIME = 1000 (10 sec
accumulation).
3.
Read the AWATTHR_HI register.
4.
AWATTOS is calculated as
13
2
_
_
−
×
×
−
=
DSP
MEASURED
EXPECTED
f
Time
on
Accumulati
HI
AWATTHR
HI
AWATTHR
AWATTOS
AWATTHR_HI
EXPECTED
=
Icalibration
FSP
×
V
FSP
×
Full-Scale Power Codes
×
Accumulation Time
× 8000 × 2
−13
= 0.0002 × 0.311 × 20,694,066 × 10 sec × 8000 × 2
−13
= 12570
0xA1
161
2
8000
10
000
,
11
12570
13
=
=
×
×
−
=
−
AWATTOS
5.
To compute AVAROS, apply a nominal voltage and offset
calibration current at power factor = 0.
Follow similar steps to obtain BPGAIN, BWATTOS, BVAROS,
CPGAIN, CWATTOS, and CVAROS.
CONVERSION CONSTANTS
Conversion constants are used to convert
register
readings into physical parameters. When the device is calibrated
to the full-scale ADC codes given in Table 29, the conversion
constants for the example system are calculated as follows:
μArms/LSB
0036
.
2
092
,
702
,
52
0.0947
10
10
10
LSB
μArms
6
6
=
×
×
=
−
×
×
=
codes
RMS
scale
Full
I
Inominal
Constant
Conversion
Current
FSP
μVrms/LSB
4225
.
13
092
,
702
,
52
311
.
0
10
220
10
LSB
μVrms
6
6
=
×
×
=
−
×
×
=
codes
RMS
scale
Full
V
Vnominal
Constant
Conversion
Voltage
FSP
/mVA)/LSB
mWATT/mVAR
(
6097
.
3
066
,
694
,
20
311
.
0
0947
.
0
10
220
10
10
LSB
/mVA
mWATT/mVAR
3
3
=
×
×
×
×
=
−
×
×
×
×
=
codes
RMS
scale
Full
V
I
Vnominal
Inominal
Constant
Conversion
Power
FSP
FSP
VAHr)/LSB
VARHr/
WATTHr/
(
0268
.
1
3600
2
066
,
694
,
20
311
.
0
0947
.
0
10
220
10
3600
2
10
LSB
VAHr
VARHr/
WATTHr/
13
6
13
6
µ
µ
µ
=
×
×
×
×
×
×
=
×
×
−
×
×
×
×
=
µ
µ
µ
−
−
codes
RMS
scale
Full
V
I
Vnominal
Inominal
Constant
Conversion
Energy
FSP
FSP
The physical parameters are obtained by multiplying the
register readings with the respective conversion constants.
For example, if the AIRMS register reading is 10,540,400
decimal codes,
Phase A rms current
(A rms)
= 2.0036 µA rms/LSB × 10,540,400
= 21.12 A rms