WAGO-I/O-SYSTEM 750
Function Description
37
750-493 3-Phase Power Measurement Module
Manual
Version 1.2.0
Calculating Power and Energy
The individual time-synchronous scan values for currents and voltages are used to
calculate active power (P). Phase shifts between currents and voltages are taken
into account when calculating power.
The time integration of power yields the energy per phase.
Determining the Frequency
Phase frequencies are determined by zero-crossing detection of the scanned
signals.
Calculating the Power Factor cos phi
The power factor cos phi is calculated from the phase shift between current and
voltage of the fundamental wave of the respective phase.
The I/O module can be configured, so that the cos phi is output with or without
sign (see section "Commissioning" > "Configuration with WAGO-I/O-
CHECK
").
If a sign is put out, it is
not
the information acquisition (+) or delivery (-) of active
power (P), but a statement on the load on the network:
•
A positive (+) sign of the cos phi means
inductive load
•
A negative (-) sign of the cos phi means
capacitive load
Together with the sign of the active power, you can determine the quadrants in the
4-quadrant display for an AC network:
Figure 7: 4-Quadrant Display of Active and Reactive Power
