ABB RELION REX640 Technical Manual page 1583

1MRS759142 C
REX640
Technical Manual
zero-sequence voltage is stored as a new reference voltage U
network admittances are stored as new reference admittances Y
Y (for more information, see
asymm_ref
If the change in the measured zero-sequence voltage exceeds the setting V Res change
level with respect to U
ref
zero-sequence voltage must exceed the threshold at least by the time defined with
Tuning delay setting, otherwise the start of the tuning procedure is canceled.
Zero-sequence voltage change can be determined considering the voltage amplitude
only or a phasor value. Setting V Res Meas mode is used to select between these two
modes. The available options are "Amplitude" and "Phasor". The phasor triggering
mode is explained in Figure
the relation between present zero-sequence voltage and the reference voltage. When
TUNING_TRIGG value is below 100%, the controller is at stand-by. When
TUNING_TRIGG value is above 100%, that is, Uo vector in
area, the tuning delay is started.
Im(U)
GUID-11BF3C5D-6654-4566-B691-8C077E4EE521 V1 EN
Figure 820: Phasor triggering mode
Level detector also includes a threshold-based earth-fault detection functionality. The
detection is based on V Res EF level voltage threshold setting. If the measured zero-
sequence voltage exceeds the threshold at least by the time defined in Transient time
EF setting, the earth fault is indicated by activating the EARTH_FAULT output and the
controller proceeds as described in Operation during earth faults in this chapter.
The delay defined in Tuning delay can be bypassed by activating ST_TUNING input,
for example, via HMI application. When the rising edge of the signal is detected, the
controller skips the tuning delay and proceeds immediately with the coil automatic
tuning procedure. The automatic tuning procedure can be started with ST_TUNING
Network parameter calculation
, then a new coil tuning procedure is released. The measured
820. Monitored data output TUNING_TRIGG indicates
U
0
Section 9
Control functions
. Also, the calculated
ref
and
symm_ref
in this chapter).
Figure 820 enters the red
Red area
= Trigger of tuning procedure
Green area (r= dUo threshold)
= No trigger
Re(U)
dUo threshold
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