ABB RELION REX640 Technical Manual page 931

1MRS759142 C
REX640
Technical Manual
GUID-34CCAC6F-F2CD-4EBE-B668-AC34AABA389E V1 EN
Figure 502: Defined zones
The impedance is continuously monitored for detecting an out of step condition.
When the impedance enters inside from the outer blinder, the out of step detection
timer is triggered. If impedance remains between outer and inner blinder for the
duration of the Swing time setting, output SWING is activated. If the impedance enters
the mho circle in zone 1, out of step blocking (OSB) for zone 1 is detected and output
OSB is activated, or if the impedance enters the mho circle in zone 2, OSB for zone 2
is detected and output OSB_Z2 is activated if setting Zone 2 enable is set to "Yes".
Both OSB and OSB_Z2 can be activated if the impedance passes through zone 1 and
zone 2 while inside the mho circle. The OSB or OSB_Z2 output deactivates when
impedance exits and remains outside the mho circle and the inner blinder for a
duration of five cycles.
Activation of the OPERATE output depends on the Oos operate mode selected. The
available options are "Way in", "Way out", and "Adaptive". If the "Way in" option is
selected, the function triggers the delay timer after detecting an OSB condition. When
the set Operate delay time has elapsed, the OPERATE output is activated. When using
the "Way in" option, the zone-related settings and zone slip counters are not
applicable.
If the "Way out" option is selected, after detecting an OSB condition, the function
further checks if impedance exits the outer blinder. On exiting the outer blinder, Way
out timer defined by Operate delay time setting is triggered and the respective zone
Section 4
Protection functions
925