WAGO-I/O-SYSTEM 750 XTR
Connect Devices 161
750-495/040-00x 3-Phase Power Measurement Module 690 V
Manual
Version 1.2.0
7.7.1.2
Measurement in Δ Networks with a Grounded Line Conductor
For measurement in 3-phase networks with a grounded line conductor, the
I/O module offers the 2-wattmeter method (Aron circuit/Blondel’s Theorem)
connection option.
7.7.1.2.1 2-Wattmeter Method (Aron Circuit/Blondel’s Theorem)
For voltage measurement, set the topology to “3-Wire Wye/Delta” (“3-W”) in
WAGO-I/O-
Check
.
This topology is available with firmware versions 05 and above and WAGO-
I/O-
Check
versions IO-3.18.1 (CS0609) and above.
This measurement circuit is used in all 3-phase networks without a neutral
conductor with a grounded line conductor and with loads in a wye or delta
connection.
The measurement circuit uses the principle of the 2-wattmeter method.
The line-to-line voltages between the grounded line conductor and the
ungrounded line conductor are measured (for example, U
12
and U
23
in the
following connection diagram). The I/O module calculates the line-to-line voltage
between the ungrounded line conductors internally from the measurement results
(U
31
in the following connection diagram, for example).
The current measurement is performed via current transformers (CTs).
The current transformer ratio must be taken into account for the correct
calculation of all values in the process image.
The nominal input voltage is:
- U
LL
= 200 V
RMS
if a voltage ≤
120 V
RMS
is parameterized for the “Secondary
Voltage” setting
- U
LL
= 400 V
RMS
if a voltage > 120 V
RMS
is parameterized for the “Secondary
Voltage” setting
Parameter 47 is used for the setting.
