ABB RELION REX640 Technical Manual page 1009

Protection and control

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1MRS759142 F

Figure 561: 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

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

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

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

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

slip counter is incremented after the set

counter value is equal to the set number of slips in the respective enabled zone, the

OPERATE output is activated. If the swing impedance passes through both zone 1

and zone 2, only the zone 1 slip counter is incremented. The zone 2 slip counter is

incremented if the impedance passes through the Mho circle but only through the

zone 2 portion. The zone 3 slip counter is incremented if the impedance misses the

Technical Manual

Swing time setting, output SWING is activated. If the impedance

Operate delay time has elapsed, the OPERATE output is activated.

Operate delay time setting is triggered and the respective zone

Oos operate mode selected. The

Operate delay time has elapsed. If the slip

Protection functions

Zone 2 enable is set