CHAPTER 7: PROTECTION
GROUPED PROTECTION ELEMENTS
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
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Middle Limit Angle
Range: 40 to 140° in steps of 1
Default: 90°
This setting specifies the middle power swing detect characteristic. It is relevant only for
the three-step mode. A typical value would be close to the average of the outer and
inner limit angles. This setting applies to mho shapes only.
Inner Limit Angle
Range: 40 to 140° in steps of 1
Default: 60°
This setting specifies the inner power swing detect characteristic. The inner
characteristic is used by the out-of-step tripping function: beyond the inner
characteristic out-of-step trip action is definite (the actual trip may be delayed as per the
Trip Mode
setting). Therefore, this angle must be selected in consideration to the power
swing angle beyond which the system becomes unstable and cannot recover.
Outer Right Blinder
Range: 0.10 to 500.00 ohms in steps of 0.01
Default: 10.00 ohms
This setting specifies the resistive reach of the right blinder for the outer mho and
quadrilateral characteristics. Set this value suitably high if no blinder is required for the
mho characteristic.
Outer Left Blinder
Range: 0.10 to 500.00 ohms in steps of 0.01
Default: 10.00 ohms
This setting specifies the resistive reach of the left blinder for the outer mho and
quadrilateral characteristics. Set this value suitably high if no blinder is required for the
mho characteristic.
Middle Right Blinder
Range: 0.10 to 500.00 ohms in steps of 0.01
Default: 10.00 ohms
This setting specifies the resistive reach of the right blinder for the middle mho and
quadrilateral characteristics. Set this value suitably high if no blinder is required for the
mho characteristic.
Middle Left Blinder
Range: 0.10 to 500.00 ohms in steps of 0.01
Default: 10.00 ohms
This setting specifies the resistive reach of the left blinder for the middle mho and
quadrilateral characteristics. Set this value suitably high if no blinder is required for the
mho characteristic.
Inner Right Blinder
Range: 0.10 to 500.00 ohms in steps of 0.01
Default: 10.00 ohms
This setting specifies the resistive reach of the right blinder for the inner mho and
quadrilateral characteristics. Set this value suitably high if no blinder is required for the
mho characteristic.
Inner Left Blinder
Range: 0.10 to 500.00 ohms in steps of 0.01
Default: 10.00 ohms
This setting specifies the resistive reach of the left blinder for the inner mho and
quadrilateral characteristics. Set this value suitably high if no blinder is required for the
mho characteristic.