ABB RELION REX640 Technical Manual page 507

Protection and control

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1MRS759142 F

Figure 289: Combined overadmittance and overconductance characteristic.

Left figure: classical origin-centered admittance circle combined with two

overconductance boundary lines. Right figure: admittance circle is set off from the

Combined overconductance and oversusceptance characteristic

The combined overconductance and oversusceptance criterion is enabled with the

Operation mode setting set to "Go, Bo".

boundary lines with the settings

of four boundary lines with the settings

reverse , Susceptance forward and Susceptance reverse . See

For the sake of application flexibility, the boundary lines can be tilted by the

angle defined with the

default, the tilt angles are zero degrees, that is, the boundary lines are straight

lines in the admittance plane. A positive

the overconductance boundary line counterclockwise from the vertical axis. A

counterclockwise from the horizontal axis.

In case of the non-directional conductance and susceptance criteria, the

Conductance reverse setting must be set to a smaller value than Conductance

forward and the Susceptance reverse setting must be set to a smaller value than

Susceptance forward .

Operation is achieved when the measured admittance moves outside the

characteristic.

The combined overconductance and oversusceptance criterion is applicable in

high-resistance earthed, unearthed and compensated networks or in the systems

where the system earthing may temporarily change during normal operation from

compensated to unearthed system.

Technical Manual

Directional mode to "Forward", the characteristic is a combination of two

Directional mode to "Non-directional", the characteristic is a combination

Conductance tilt Ang and Susceptance tilt Ang settings. By

Susceptance tilt Ang value rotates the oversusceptance boundary line

Conductance forward and Susceptance forward .

Conductance forward , Conductance

Conductance tilt Ang value rotates

Protection functions