ABB RELION REX640 Technical Manual page 531

Protection and control

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1MRS759142 F

The operation of WPWDE can be described with a module diagram. All the modules

in the diagram are explained in the next sections.

Figure 305: Function module diagram

Directional calculation

The Directional calculation module monitors the angle between the operating

quantity (residual current Io) and polarizing quantity (residual voltage Uo). The

operating quantity can be selected with the setting

options are "Measured Io" and "Calculated Io". The polarizing quantity can be

selected with the setting

and "Calculated Uo". When the angle between operating quantity and polarizing

quantity after considering the

sector, the module sends an enabling signal to Level detector. The directional

operation is selected with the

"Reverse" operation mode can be selected. The direction of fault is calculated based

on the phase angle difference between the operating quantity Io and polarizing

quantity Uo, and the value (ANGLE) is available in the monitored data view.

In the phasor diagrams representing the operation of WPWDE, the polarity of the

polarizing quantity (residual voltage Uo) is reversed. Reversing is done by switching

the polarity of the residual current measuring channel (see the connection in the

Protection relay's physical connections section).

If the angle difference lies between -90° to 0° or 0° to +90°, a forward-direction fault

is considered. If the phase angle difference lies within -90° to -180° or +90° to +180°,

a reverse-direction fault is detected. Thus, the normal width of a sector is 180°.

Technical Manual

The minus sign (-) is needed to match the polarity of calculated and

measured residual currents.

Pol signal Sel . The selectable options are "Measured Uo"

Characteristic angle setting is in the operation

Directional mode setting. Either the "Forward" or

Protection functions

Io signal Sel . The selectable