Application Guide - NP900 Series
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Figure 3.1.2.1-17 Two line to line measurements with zero sequence voltage and voltage
from side 2 for Synchro-check 2LL+U0+SS. Line to neutral voltages can be calculated
since U0 is available.
In the next figure is presented relay behavior when nominal voltage is injected to the relay
and the IED is measuring line to neutral voltages. Part of the available information from
the IED is presented as well:
Figure 3.1.2.1-18 Nominal voltage injection to the IED by using secondary test
equipment. Voltage transformer scaling is set to 20000:100 V. Voltage measurement
mode is 3LN+U4 and U4 channel is measuring zero sequence voltage which has same
ratio 20000:100 V.
