ABB RELION REX640, Техническое руководство, Страница: 1030 / 1960

the circle is shifted to the right of the X-axis and if the sign is negative, the circle
is shifted to the left of the X-axis. For an origin-centric mho characteristic,
Offset
enable is kept disabled.
When using the mho-characteristics, the
Offset and Displacement
settings are as given in the UEXPDIS function, but
Polar reach is half of
UEXPDIS
Diameter setting.
X (Reactance) pu
R (Resistance) pu
Operating Region
Polar reach
Displacement
Offset
Figure 572: Designing zones with Offset and Displacement
The offset-mho characteristic shown in Figure
Figure 572
is designed with a positive
value for
Offset and a negative value for Displacement.
More than one impedance value is available when
Impedance Meas
mode is set to "3Phase-phase", and the function considers the lowest
impedance value for starting and operating.
Timer
Once activated, the Timer activates
START
output. The time characteristic is
according to DT. When the duration of the underimpedance condition exceeds the
set definite
Operate delay time, the
OPERATE
output is activated. If the impedance
locus moves out of circular operating characteristics before the module operates,
the reset timer is activated. If the reset timer reaches the value set by Reset delay
time, the operating timer resets and the
START
output is deactivated.
The Timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operating time (DT). The value
is available in the Monitored data view.
Protection functions 1MRS759142 F
1030 REX640
Technical Manual