124 Connect Devices
WAGO-I/O-SYSTEM 750 XTR
750-495/040-00x 3-Phase Power Measurement Module 690 V
Manual
Version 1.2.0
7.6.1.8 Measurement of Multiple Ungrounded Single-Phase Networks with a
Common Neutral Conductor
The “4-Wire Wye” (“4-W”) topology is available in WAGO-I/O-
Check
for voltage
measurement.
This topology is fixed in firmware versions 04 and below and selectable in
WAGO-I/O-
Check
in firmware versions 05 and above.
The voltage transformer ratio can be parameterized in firmware versions 05 and
above and WAGO-I/O-
Check
versions IO-3.18.1 (CS0609) and above.
Up to 3 ungrounded single-phase networks with a common neutral conductor can
be connected to the I/O module.
The measurement circuit basically corresponds to the “Ungrounded 3-Phase
Network with Neutral Conductor for Power Measurement and Voltage
Measurement on 3 Line Conductors for U
LN
≤
400 V
RMS
and u
LN
≤
400 V
RMS
”
connection schematic,
Voltage measurement is performed via voltage transformers (VTs).
The current measurement is performed via current transformers (CTs) or
Rogowski Coils.
The measured values of unconnected voltage and current measurement inputs
have no significance.
For voltage measurement, the voltage to measure must be connected to each
voltage input of the I/O module. A voltage connected to a terminal cannot be
passed on for the calculation of the other phases on the firmware side.
The voltage transformer ratio and current transformer ratio must be taken into
account for the correct calculation of all values in the process image.
Always use voltage transformers with basic insulation and ground the
module-side N connection
In ungrounded single-phase networks with a neutral conductor, always use
voltage transformers with at least basic insulation and ground the module-side N
connection.
Otherwise, touch-proof protection from the system may no longer be given in the
event of a fault. This can cause electric shock or burns.