ABB SACE Tmax XT2, User Manual

Page: 62 / 207

1SDH002031A1002 ECN000092998 Rev. B SACE Tmax XT2
– XT4 | 62
RQ Protection Function
RQ protection protects against the inversion of reactive power, with threshold adjustable
according to the active power.
When the reverse reactive power enters the TRIP area determined by the protection parameters
and the powers read for a time greater than t24 the protection sends the TRIP command.
The adjustment of the Kq and Kq2 constants makes it possible to vary the trip threshold, the trip
threshold is determined by the intersection of the two TRIP areas, whose limits are based on the
parameters configured on units
Figure 22
To verify and simulate the trip times based on all the parameters, see:

Protection summary table with the operating characteristics (page 79)

Chart with tripping curve (page 93)
Parameters
Parameter Description Default
Enable
Enables/disables protection and availability on menu of the
parameters
OFF
Trip Enable
Activates/deactivates the open command: if disabled, the alarm
and the lapsing of the protection time are managed only as
information
OFF
Kq
Threshold
Defines the slope of the straight line in relation to the threshold Q24.
The value is expressed as an absolute value (angular coefficient of
the straight line), settable in a range: -2 ... 2 with 0.01 step
-2
-Q24
Threshold
Is the reactive power that is necessary for defining the trip line and
the relative TRIP area
The value is expressed both as an absolute value (kVAR) and as a
relative value (Sn), settable in a range:
0.1 Sn .. 1 Sn with 0.001 Sn step
NOTE: threshold expressed in Sn is not preceded by the
sign “-” but must be understood to be reversed reactive
power
0.1 Sn
Kq2
Threshold
Defines the slope of the straight line in relation to the threshold Q24.
The value is expressed as an absolute value (angular coefficient of
the straight line), settable in a range: -2 ..2 with 0.01 step
2