ABB RELION REX640 Technical Manual page 930

Section 4
Protection functions
924
GUID-B317B96C-A7E4-4DE1-A50B-EE3A0364218B V1 EN
Figure 501: Operating region for out of step with double blinder
An impedance is only considered to be within the mho circle if it is
also between the inner blinders.
A third zone, Zone 3, can be enabled by setting Zone 3 enable to "Yes". Zone 3 is
defined to include the area outside of the circular mho characteristic but inside the area
that is bound with the magnitude of the minimum positive-sequence current defined
by setting Min Ps Seq. Figure 502
shape of the zones should be coordinated with the settings for any distance protection
functions. The zones and their respective slip counters are applicable only for Way out
operations when the Oos operation mode setting option is "Way out" or "Adaptive".
shows the three zones. Settings that determine the
1MRS759142 C
REX640
Technical Manual