ADE7753 View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'ADE7753' PDF : 60 Pages View PDF
CALCULATE CFDEN VALUE FOR DESIGN
WRITE CFDEN VALUE TO CFDEN REGISTER
ADDR. 0x15 = CFDEN
SET ITEST = Ib, VTEST = VNOM, PF = 1
SET HALF LINECYCLES FOR ACCUMULATION
IN LINECYC REGISTER ADDR. 0x1C
SET MODE FOR LINE CYCLE
ACCUMULATION ADDR. 0x09 = 0x0080
ENABLE LINE CYCLE ACCUMULATION
INTERRUPT ADDR. 0x0A = 0x04
RESET THE INTERRUPT STATUS
READ REGISTER ADDR. 0x0C
NO
INTERRUPT?
YES
RESET THE INTERRUPT STATUS
READ REGISTER ADDR. 0x0C
NO
INTERRUPT?
YES
READ LINE ACCUMULATION ENERGY
ADDR. 0x04
CALCULATE WGAIN. SEE EQUATION 47.
WRITE WGAIN VALUE TO THE WGAIN
REGISTER: ADDR. 0x12
02875-A-007
Figure 81. Calibrating Watt Gain Using an Accurate Source
Equation 47 describes the relationship between the expected
LAENERGY value and the LAENERGY measured in the test
condition:
WGAIN
=
INT
⎜⎛
⎜
⎝
⎜⎛
⎜⎝
LAENERGYIB(expected )
LAENERGYIB(nominal)
−1⎟⎟⎠⎞× 212
⎟⎞
⎟
⎠
(47)
ADE7753
The nominal LAENERGY reading, LAENERGYIB(nominal), is the
LAENERGY reading with the test current applied. The
expected LAENERGY reading is calculated from the following
equation:
LAENERGYIB(expected) =
INT
⎜⎛
⎜
⎜⎜⎝
CFIB(expected) × Accumulation Time(s)
CFNUM +1 ×WDIV
CFDEN +1
⎟⎞
⎟
⎟⎟⎠
(48)
where CFIB(expected)(Hz) is calculated from Equation 34, accumula-
tion time is calculated from Equation 37, and the line period is
determined from the PERIOD register according to Equation 38.
For this example:
Meter Constant:
MeterConstant(imp/Wh)
= 3.2
Test Current:
Ib = 10 A
Line Voltage:
Vnominal = 220 V
Line Frequency:
fl = 50 Hz
Half Line Cycles:
LINECYCIB = 2000
CF Numerator:
CFNUM = 0
CF Denominator:
CFDEN = 489
Energy Reading at Base Current:
LAENERGYIB (nominal) = 17174
Period Register Reading: PERIOD = 8959
Clock Frequency:
CLKIN = 3.579545 MHz
CFexpected is calculated to be 1.9556 Hz according to Equation 34.
LAENERGYexpected is calculated to be 19186 using Equation 48.
CFIB(expected)(Hz) =
3.200 imp/Wh× 220 V×10 A
×(cos(ϕ) = 1.9556 Hz
3600 s/h
LAENERGYIB(expected) =
INT
⎜⎛
⎜
⎜⎜⎝
CFIB(expected)
×
LINECYCIB / 2× PERIOD×8
CFNUM +1 ×WDIV
CFDEN +1
/ CLKIN
⎟⎞
⎟
⎟⎟⎠
LAENERGYIB(expected) =
INT
⎜⎛
⎜
⎜⎜⎝
1.9556
×
2000
/
2
×
8959 × 8
1
489 +1
/(3.579545
×10
6
)
⎟⎞
⎟1
⎟⎟⎠
=
INT(19186.4) = 19186
WGAIN is calculated to be 480 using Equation 47.
WGAIN
=
INT
⎜⎝⎛ ⎜⎝⎛
19186
17174
− 1⎟⎠⎞
× 212
⎟⎞
⎠
=
480
Note that WGAIN is a signed twos complement register.
With WDIV and CFNUM set to 0, LAENERGY can be
expressed as
Rev. C | Page 41 of 60
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