BL0952A/BL6513
Three-
Three-phase Active
Energy Meter
When one phase power of three phases is negative, it’s value will counteract the other
positive terms.
If the BL0952A/BL6513/BL6511 is configured to execute the absolute value sum of the three
active powers, the sum of the three-phase power is calculated as follows:
P
TOTAL
=
P
A
+
P
B
+
P
C
THE OPRATION PROCESS OF THREE PHASE ENERGY MEASURE SIGNAL
Fig.5
Signal Processing Block Diagram
In BL0952A/BL6513/BL6511, the six voltage signals from the current and voltage
transducers are digitized with ADCs. The instantaneous power signal P(t) is generated by a direct
multiplication of the current and voltage signals of each phase. In order to extract the real power
component (i.e., the dc component), the instantaneous power signal is low-pass filtered on each
phase. Then, The total real power information is then obtained by adding the individual phase real
power (the arithmetic sum or the absolute value sum).
The output of three-phase power sum is sent to the digital-frequency module. In this module,
the total real power is accumulated during the given time, and converted to the periodic frequency
output which is therefore proportional to the average real power. Because of its high output
frequency and therefore, shorter integration time, the CF output is proportional to the
instantaneous real power. This pulse is useful for system calibration purposed that would take
place under steady load conditions.
By dividing the high output CF, F1 and F2 can be obtained. The outputs F1 and F2 operate at
a much lower frequency, which can drive the 2-phase stepper motors by eight kinds modes. The
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4/21/2009
Total
8 Pages
BELLING [ SHANGHAI BELLING CO., LTD. ]
