User's Manual

CENTRON Meter Technical Reference Guide 3-1
Chapter 3 Operation: Base Metrology
This chapter describes the measurement technique used for the base metrology on
the CENTRON meters.
CENTRON 1S, 2S CL200, and 3S
The CENTRON meter is a solid-state meter which uses the inherent multiplication
properties of the Hall Effect to measure power. The Hall Effect principle relies on a
physical property: a conductor which carries a current in a magnetic field
generates a voltage difference across the conductor proportional to the product of
the current and the magnetic field.
The voltage V
out
created at the output of the Hall device:
Where
i
b
is the biasing current (derived from the line voltage)
B is the magnetic field density (derived from the line current)
K is the Hall coefficient (analogous to a gain factor in any meter)
K could be viewed as the Hall sensor intrinsic gain and is maximized by the
appropriate choice of semiconductor materials that have been uniquely optimized
by SchlumbergerSema for the CENTRON meter.
For the metering application, the biasing current i
b
applied to the sensor is
generated from the line voltage (V) using a resistor (R).
The magnetic field (B) is generated by the line currents (I = I
1
+ I
2
) that flow
through two conductors looped around the core.
Where
C is a constant that is dependent upon the geometric and magnetic properties
of the coil
This field is focused to flow through the Magnetic Core’s air gap where the Hall
sensor is precisely positioned. The voltage, Vout, which is formed on the Hall
Effect device is proportional to the input watts (see Figure 3.1).
V
out
Ki
b
B×=
i
b
VR⁄=
B CI× CI
1
I
2
+()×==