Application Guide - NP900 Series
26 (504
)
Figure 3.1.2.1-19 Voltage injection during earth fault 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.
3.1.2.2
T
ROUBLESHOOTING
It is possible that for some reason the measured voltages may not be as expected. For
these cases following checks may be helpful.
Problem
Check / Resolution
Measured voltage amplitude in all phases does not
match for what is injected.
Scaling settings or voltage measurement mode may be
wrong, check from Measurement
Transformers
VT Module that the settings match for what is expected.
Measured voltage amplitude does not match for one
measured phase or calculated U0 is measured when
there should not be any.
Wiring connections from injection device or VT:s to the
IED.
Measured voltage amplitudes are all ok and equal but
the angles are strange.
Voltage unbalance protection trips immediately when it
is activated.
Earth fault protection trips immediately when it is
activated and voltage is calculated.
Voltages are connected into the measurement module,
but the order or polarity of one or all phases is
incorrect.
Go to Measurement
Phasors and check the voltage
vector diagram.
When all is correctly connected the diagram should
look as below with symmetric feeding:
Содержание NP900 Series
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Страница 49: ...Application Guide NP900 Series 49 504 A996A Figure 3 2 1 3 25 Definite time operating characteristics...
Страница 50: ...Application Guide NP900 Series 50 504 A996A Figure 3 2 1 3 26 IEC predefined characteristics NI VI LTI and EI...
Страница 52: ...Application Guide NP900 Series 52 504 A996A Figure 3 2 1 3 28 IEEE predefined characteristics EI MI and VI...
Страница 243: ...Application Guide NP900 Series 243 504 A996A Figure 3 3 2 1 122 NPS biased thermal trip curves with kNPS values 7 and 10...
Страница 491: ...Application Guide NP900 Series 491 504 A996A 3 7 5 6 SETTING EXAMPLE...
Страница 504: ...Application Guide NP900 Series 504 504 A996A A996A...