STPMC1 ST Microelectronics, STPMC1 Datasheet - Page 67

• Manufacturer Part Number: STPMC1
• Description: Programmable poly-phase energy calculator IC
• Manufacturer: ST Microelectronics

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STPMC1
10.2
In case of a non Rogowski sensor, the corresponding products are:
Equation 31
P
Equation 32
P
Then a subtraction of P
Equation 33
P = (P
where:
Equation 34
k
This gives the same result for P in case of non Rogowski sensor, substituting B and k
with C and k
Equation 35
P = (P
where:
Equation 36
k
The result in
line. The division by 2 is a feature of
eliminates the spread of results due to asynchronism with the line. This fact enables fast a
calibration procedure which is used to set the target constant of meter k
A sensitivity analysis of k
Equation 37
Equation 38
It is clear that the device is responsible for A
are omitted, because they are not subject to aging or temperature variations due to digital
implementation.
Reactive energy calculation
The natural reactive power (ART = 0) of the line is computed as follows.
First, 16-bit voltage from the 3
current stream from the 1
P
P
k
k
1
2
P
P
= k
= k
= v
= v
/k
/k
P
P
D
D
d
di
2
2
= L/L + R
= R
v
- P
k
- P
k
v
si
L
S
s
k
1
1
= - AC k
= AC k
) / 2 = (AB cos ) k
INT
) / 2 = (AC cos ) / 2 = (Uk
S
S
Equation 34
:
/ R
S
DIF
1
DIF
+ R
/ (R
k
INT
k
1
INT
1
1
+R
/ (R
from P
P
sin ( t) sin ( t + ) = AC [cos
st
and
cos ( t) cos ( t + ) = - AC [cos
yields:
2
stage (
1
)( R
+R
rd
Equation 35
Doc ID 15728 Rev 1
INT
2
2
stage (
2
)( R
is performed:
/R
/ 2 = (Uk
Equation 13
2
-
2
D
/R
Equation 19
Ik
subtractor. The absence of harmonic components
2
R
S
-
1
D
is proportional to the DC part of active power of
cos ) / 2 = U
/R
U
Ik
, A
R
L
1
) + A
or
1
cos ) k
I
/R
and V
Equation 22
1
) + A
or
U
/A
Equation 27
REF
INT
U
RMS
U
+ A
- cos (2
/ 2 = U
/A
parts. The parts k
Energy calculation algorithm
U
I
) and the frequency
RMS
+ cos (2
I
+ A
/A
I
RMS
cos
) is multiplied by the
- 2 V
I
/A
t + )] / 2
I
I
RMS
P
- 2 V
.
k
REF
t + )] / 2
P
cos
/V
U
REF
, k
REF
I
/V
k
and k
P
REF
L
67/76
k
INT
INT