ABB RELION REX640 Technical Manual page 1288

Protection and control

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Protection related functions

Figure 729: Functional module diagram

Directional detector

When "Neg. seq. volt." selection is made using the

Directional detector module compares the angle of the negative-sequence current

) to the negative-sequence voltage (–U

angle as the reference, the negative-sequence current angle is compared to the

Characteristic angle setting. If the angle difference is within the operating sector

The operating sector is defined by the settings

angle , Min forward angle and Min reverse angle . The options that can be selected for

Directional mode settings are "Forward" and "Reverse".

Characteristic angle is also known as Relay Characteristic Angle RCA, Relay Base

Angle or Maximum Torque Line.

Direction mode setting, the Enable signal is sent to Timer.

The value of

Characteristic angle should be chosen in such way that all

the faults in the operating direction are seen in the operating zone and all

the faults in the opposite direction are seen in the backward zone.

Pol quantity setting, the

). Using the negative-sequence voltage

Max forward angle , Max reverse

1MRS759142 F

Technical Manual