ABB RED650, Руководство по применению

Страница: 197 / 454

9.1.3.6 Settings for two step undervoltage protection
M13851-65 v14
The following settings can be done for Two step undervoltage protection
UV2PTUV:
ConnType : Sets whether the measurement shall be phase-to-earth fundamental
value, phase-to-phase fundamental value, phase-to-earth RMS value or phase-to-
phase RMS value.
Operation : Off or On .
UBase (given in GlobalBaseSel ): Base voltage phase-to-phase in primary kV. This
voltage is used as reference for voltage setting. UV2PTUV will operate if the
voltage becomes lower than the set percentage of
UBase . This setting is used when
ConnType is set to PhPh DFT or PhPh RMS . Therefore, always set UBase as rated
primary phase-to-phase voltage of the protected object. For more information, refer
to the
Technical manual .
The setting parameters described below are identical for the two steps ( n = 1 or 2).
Therefore, the setting parameters are described only once.
Characteristicn : This parameter gives the type of time delay to be used. The setting
can be Definite time , Inverse Curve A , Inverse Curve B , Prog. inv. curve . The
selection is dependent on the protection application.
OpModen : This parameter describes how many of the three measured voltages
should be below the set level to give operation for step n. The setting can be 1 out
of 3 , 2 out of 3 or 3 out of 3 . In most applications, it is sufficient that one phase
voltage is low to give operation. If UV2PTUV shall be insensitive for single phase-
to-earth faults,
2 out of 3 can be chosen. In subtransmission and transmission
networks the undervoltage function is mainly a system supervision function and 3
out of 3 is selected.
Un< : Set operate undervoltage operation value for step n , given as % of the
parameter UBase . The setting is highly dependent on the protection application. It
is essential to consider the minimum voltage at non-faulted situations. Normally,
this non-faulted voltage is larger than 90% of the nominal voltage.
tn : time delay of step n , given in s. This setting is dependent on the protection
application. In many applications the protection function shall not directly trip
when there is a short circuit or earth faults in the system. The time delay must be
coordinated to the other short circuit protections.
tResetn : Reset time for step n if definite time delay is used, given in s. The default
value is 25 ms.
tnMin : Minimum operation time for inverse time characteristic for step n , given in
s. When using inverse time characteristic for the undervoltage function during very
low voltages can give a short operation time. This might lead to unselective
tripping. By setting
t1Min longer than the operation time for other protections, such
unselective tripping can be avoided.
1MRK 505 393-UEN B
Section 9
Voltage protection
Line differential protection RED650 2.2 IEC 191
Application manual