2-Wattmeter Method (Aron Circuit/Blondel's Theorem) - WAGO 750-495/040-00 Series Manual

WAGO-I/O-SYSTEM 750 XTR
750-495/040-00x 3-Phase Power Measurement Module 690 V

7.7.2.3.2 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 ungrounded 3-phase networks without a
neutral conductor and with loads in a wye or delta connection.
The measurement circuit uses the principle of the 2-wattmeter method.
2 electrically isolating voltage transformers (VTs) reduce the 2 line-to-line
voltages U
u and u
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calculates line-to-line voltage u
The current measurement is performed via current transformers (CTs) or
Rogowski Coils.
Always use voltage transformers with reinforced insulation and ground the
module-side N connection
In ungrounded 3-phase networks, 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.
The voltage transformer ratio and 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 = 200 V
LL
Voltage" setting
- u = 400 V
LL
Voltage" setting
Parameter 47 is used for the setting.
and U to u and u
12 23 12
are measured. From the measurement results, the I/O module first
31
if a voltage ≤ 120 V
RMS
if a voltage > 120 V
RMS
with electrical isolation. Line-to-line voltages
23
and then line-to-line voltages U
is parameterized for the "Secondary
RMS
is parameterized for the "Secondary
RMS
Connect Devices 175
, U and U .
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Manual
Version 1.2.0