138 Connect Devices
WAGO-I/O-SYSTEM 750 XTR
750-495/040-00x 3-Phase Power Measurement Module 690 V
Manual
Version 1.2.0
7.6.2.4 Measurement of Multiple Grounded Single-Phase Networks with
Different Neutral Conductors
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 grounded single-phase networks with different neutral conductors can be
connected to the I/O module.
Voltage measurement is performed via voltage transformers (VTs). Voltages u
L1
,
u
L2
and u
L3
are measured. The I/O module calculates voltages U
L1
, U
L2
and U
L3
internally from the measurement results.
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. The measured values for the line-to-line voltages that the
I/O module outputs have no significance either.
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 reinforced insulation and ground the
module-side N connection
When connecting multiple grounded single-phase networks with different neutral
conductors, always use voltage transformers with reinforced 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.
Do not connect the neutral conductors of the single-phase networks to
each other on the primary side of the voltage transformers
The neutral conductors of the different single-phase networks must not be
connected to each other on the primary side of the voltage transformers.
If they are, unwanted currents can flow between the different networks.