ABB RELION REX640 Technical Manual page 505

Protection and control

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1MRS759142 F

Forward directional overconductance characteristic

The forward directional overconductance criterion is enabled with the

mode setting set to "Go" and Directional mode set to "Forward". The characteristic

is defined by one overconductance boundary line with the

setting. For the sake of application flexibility, the boundary line can be tilted with

the angle defined with the

zero degrees, that is, the boundary line is a vertical line in the admittance plane. A

positive tilt value rotates the boundary line counterclockwise from the vertical axis.

Operation is achieved when the measured admittance moves over the boundary

Figure 287: Forward directional overconductance characteristic. Left figure: classical

forward directional overconductance criterion. Middle figure: characteristic is tilted

with negative tilt angle. Right figure: characteristic is tilted with positive tilt angle.

Forward directional oversusceptance characteristic

The forward directional oversusceptance criterion is enabled with the

mode setting set to "Bo" and Directional mode to "Forward". The characteristic

is defined by one oversusceptance boundary line with the

setting. For the sake of application flexibility, the boundary line can be tilted by the

angle defined with the

degrees, that is, the boundary line is a horizontal line in the admittance plane. A

positive tilt value rotates the boundary line counterclockwise from the horizontal

Operation is achieved when the measured admittance moves over the boundary

Technical Manual

Conductance tilt Ang setting. By default, the tilt angle is

The forward directional overconductance criterion is applicable in high-

resistance earthed and compensated networks. It must not be applied in

unearthed networks.

Susceptance tilt Ang setting. By default, the tilt angle is zero

The forward directional oversusceptance criterion is applicable in

unearthed networks. It must not be applied to compensated networks.

Protection functions

Conductance forward

Susceptance forward