ABB 615 series Technical Manual page 695

1MAC059074-MB A
615 series ANSI
Technical Manual
GUID-94CC2B30-D7CC-4CB0-AB7C-C6261C641D37 V1 EN
Figure 343: 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 TRIP output depends on the Oos trip mode selected. The options
available 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 Trip delay
time has elapsed, the TRIP output is activated. When using the "Way in" option, the zone-
related settings and zone slip counters are not applicable.
Section 4
Protection functions
689