71m6515h Maxim Integrated Products, Inc., 71m6515h Datasheet - Page 24

• Manufacturer Part Number: 71m6515h
• Description: 71m6515h Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

Calibration with Three Measurements
The simplest calibration method is to make three measurements. Typically, a voltage measurement and two Watt-hour (Wh)
measurements are made.
If the voltage measurement has the error E
with φ
zero when the meter is accurate and negative when the meter runs slow. The fundamental frequency is f
where f
PHADJ_A = 0.
From the voltage measurement, we determine that
1.
We use the other two measurements to determine φ
2.
2a.
3.
3a.
Combining 2a and 3a:
4.
5.
6.
and from 2a:
7.
Now that we know the A
Page: 24 of 57
CAL
L
_
φ
= 0 and E
E
E
E
E
tan(
A
A
A
S
V
S
XI
0
XV
60
60
60
XV
is the sample frequency (2520.62Hz). Set all calibration factors to nominal: CAL_IA = 16384, CAL_VA = 16384,
NEW
=
=
φ
=
A
=
=
=
=
=
tan
S
XI
IV
A
A
IV
E
)
A
=
E
XV
=
XV
=
XV
0
−
V
60
A
1
E
CAL
A
+
⎛
⎜ ⎜
⎝
(
cos(
A
XV
cos(
A
+
0
is measured with φ
E
E
XV
(
(
A
XI
XI
+
IV
E
1
0
0
E
IV
A
XV
E
1
0
[
φ
cos(
+
A
+
φ
0
_
cos(
XV
E
XI
60
cos(
+
S
S
1
XI
) 1
V
cos(
+
60
, A
)
)
cos(
) 1
−
) 1
cos(
tan(
φ
−
XI
60
tan(
) 0
E
S
, and φ
tan(
60
E
0
)
0
)
60
0
60
cos(
+
−
)
60
cos(
60
φ
A
)
−
)
S
S
XV
φ
⎞
⎟ ⎟
⎠
φ
)
)
errors, we calculate the new calibration voltage gain coefficient from the previous ones:
60
L
S
tan(
S
© 2005-2008 TERIDIAN Semiconductor Corporation
−
A
= 60. These values should be simple ratios—not percentage values. They should be
)
)
)
XI
1
+
−
=
φ
V
sin(
1
tan(
S
and the two Wh measurements have errors E
A
=
)
XV
60
A
60
XV
S
A
)
)
sin(
and A
XI
sin(
A
cos(
XI
φ
φ
XI
cos(
S
S
.
φ
)
)
]
cos(
S
−
−
)
60
1
1
−
60
1
−
φ
)
S
)
−
1
Energy Meter IC
0
and E
DATA SHEET
71M6515H
60
, where E
0
. T is equal to 1/f
0
MARCH 2008
is measured
V1.4
S
,