Operations; Out Of Step Blocking Unit - GE MLP1000 Manual

Configurable output selection is performed in the factory when ordered.

4.19 OPERATIONS

The MLP program allows the following operations to be performed:
- Breaker opening.
- Breaker close.
- Recloser block. (MLP2000 and MLP3000).
- Recloser unblock (MLP2000 and MLP3000).
- Relay synchronism
The synchronism operation can only be performed via serial communications, not
through the relay keyboard.

4.20. OUT OF STEP BLOCKING UNIT

The out of step blocking units is designed to identify a three phases power
oscillation fault situation. This prevents the distance protection system from tripping
unnecessarily.
There is a setting which allows you to disable this setting as well as a timer to
determine the speed at which the impedance, as seen by the relay, enters into the tripping
zone. This speed allows us to identify a phase power oscillation fault situation.
Figure 17 illustrates the state diagram for this functions as well as the X/J plane
characteristic
To better understand this, we will explain the operation with an example.
In a fault situation, the impedance crosses the OSB zone (in tomato form) and stars
the oscillation detection timer (TL3). When this timer terminates, the M3 measuring unit
(circle) is checked. Because of the fault, which developed rapidly, this unit will be activated.
In this case the relay will not be blocked by a power oscillation.
Needless to say, if the impedance evolves slowly, when the aforementioned timer
terminates, the M3 measuring unit will not vet have been activated, showing that the power
oscillation had occurred. In this way the relay will block the trip. Once leaving the OSB
zone, the relay will wait a fixed time of 50 ms before returning to the initial or stand-by
state.
GEK-98846A
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