• 3LN+U4 (three line-to-neutral voltages and U4 can be used for either zero sequence voltage
or synchrochecking)
• 3LL+U4 (three line-to-line voltages and U4 can be used either for zero sequence voltage or
synchrochecking)
• 2LL+U3+U4 (two line-to-line voltages and the U3 and the U4 channels can be used for
synchrochecking, zero sequence voltage, or for both)
The 3LN+U0 is the most common voltage measurement mode. See below for example connections of
voltage line-to-line measurement (3LL on the left, 2LL on the right).
Figure. 5.2.2 - 70. Example connections for voltage line-to-line measurement.
If only two line-to-line voltages are measured, the third one (U
L31
) is calculated based on the U
L12
and
U
L23
vectors. When measuring line-to-line voltages, the line-to-neutral voltages can also be calculated
as long as the value of U0 is measured and known.
The voltage measurement channel U4 can also be used to measure either the zero sequence voltage
(U0) or the side 2 voltage of the circuit breaker (Synchrocheck). If the 2LL+U3+U4 mode is selected,
the third channel (U3) can be used for this purpose. Please note that U0 can only be measured by
using a single channel.
In the image below is an example of 2LL+U0+SS, that is, two line-to-line measurements with the zero
sequence voltage and voltage from side 2 for Synchrocheck. Since U0 is available, line-to-neutral
voltages can be calculated.
A
AQ
Q-F215
-F215
Instruction manual
Version: 2.04
74