Single Phase, 1-Element Metering - ABB A43 User Manual

Measurement Methods
Illustration The type of load can be represented geometrically by 4 power
quadrants, see figure below.
Import of
reactive
power
Export of
reactive
power

7.1.1 Single Phase, 1-Element Metering

1- element metering in a 2-wire system
In a 2 -wire installation a single phase meter is used. Normally the 2 wires are
a phase voltage and the neutral.
The active energy consumed by the load is the product of momentary voltage
and current integrated over the desired measuring time period.
Calculating In the case where no harmonics is present and the rms value of the voltage
and current is constant, the active power can be expressed as:
active power
P = U
Where  is the phase angle between the voltage and the current.
A43/A44
User Manual
Export of
active power
-
+
2
-
3
* cos 
* I
rms rms
86
Import of
active power
+
1
S
Q

P
4
2CMC48001M0201
Revision: C