CENTRON® Polyphase Meter Technical Reference Guide
13
C
H A P T E R
3
Operation: Base Metrology
In This Chapter
Metrology ............................................................................................................13
Surge Protection ..................................................................................................14
Sampling..............................................................................................................14
Voltage and Current Measurement ......................................................................15
Metrology
The CENTRON Polyphase meter is a solid-state meter which uses the Hall Effect (one per
phase) to measure metered current and voltage dividers (one per phase) to measure metered
voltage as indicated in block diagram below.
DC
DC
AC
I
C
=I
Bias
* I
Line
I
C
+
V
C
+
I
Line
I
Bias
V
C
V
Bias
Magnetic
Core
Hall
Sensor
DC
AC
I
B
=I
Bias
* I
Line
I
B
+
V
B
+
I
Line
I
Bias
V
B
V
Bias
Magnetic
Core
Hall
Sensor
AC
I
A
=I
Bias
* I
Line
I
A
+
V
A
+
I
Line
I
Bias
V
A
Magnetic
Core
Hall
Sensor
A/D
DSP
Wh
VAh
VARh
PF
LED
V
Bias
Figure 8: CENTRON Polyphase Metrology
The metrology performs the direct sampling of the voltage and current waveforms and the
raw processing of these samples to compute all the energy quantities. It is comprised of a
dedicated microprocessor and an analog-to-digital (A/D) converter. Low level signals
proportional to the service voltages and currents are connected to the analog inputs of the
A/D converters. These converters, which are contained in one package, individually sample
the signals and send the digital results to the microprocessor 1,920 times per second. The
microprocessor takes these samples, applies precision calibration corrections and computes
all the quantities required for the specific meter configuration.
