GE D90 Plus Instruction Manual page 216

GROUPED PROTECTION ELEMENTS
206
The relay internally performs zero-sequence compensation for the protected circuit
based on the values entered for the
configured to do so, zero-sequence compensation for mutual coupling based on the
values entered for the
Z0M/Z1 Magnitude
Reach and RCA settings in terms of positive-sequence quantities.
Reverse Reach
Range: 0.02 to 500.00 ohms in steps of 0.01
Default: 2.00 ohms
This setting specifies the reverse reach of the zone set as non-directional. The value
must be entered in secondary ohms. This setting does not apply when the zone direction
is set to "Forward" or "Reverse."
Reverse Reach RCA
Range: 30 to 90° in steps of 1
Default: 85°
This setting specifies the angle of the reverse reach impedance if the zone is set to non-
directional. This setting does not apply when the zone direction is set to "Forward" or
"Reverse."
Polarizing Current
Range: Zero-sequence, Negative-Sequence
Default: Zero-sequence
This setting applies only if the
used by the reactance comparator of the quadrilateral characteristic. Either the zero-
sequence or negative-sequence current can be used. In general, a variety of system
conditions must be examined to select an optimum polarizing current. This setting
becomes less relevant when the resistive coverage and zone reach are set
conservatively. Also, this setting is more relevant in lower voltage applications such as
on distribution lines or cables, as compared with high-voltage transmission lines. This
setting applies to both the zone 1 and reverse reactance lines if the zone is set to non-
directional.
Non-Homogeneous Angle
Range: –40.0 to 40.0° in steps of 0.1
Default: 0.0°
This setting applies only if the
the angle of the polarizing current of the reactance comparator for non-homogeneity of
the zero-sequence or negative-sequence networks. In general, a variety of system
conditions must be examined to select this setting. In many applications this angle is
used to reduce the reach at high resistances in order to avoid overreaching under far-
out reach settings and/or when the sequence networks are greatly non-homogeneous.
This setting applies to both the forward and reverse reactance lines if the zone is set to
non-directional.
Comparator Limit
Range: 30 to 90° in steps of 1
Default: 90°
This setting shapes the operating characteristic. In particular, it enables a lens-shaped
characteristic of the mho function and a tent-shaped characteristic of the quadrilateral
function reactance boundary. If the mho shape is selected, the same limit angle applies
to mho and supervising reactance comparators. In conjunction with the mho shape
selection, this setting improves loadability of the protected line. In conjunction with the
quadrilateral characteristic, this setting improves security for faults close to the reach
point by adjusting the reactance boundary into a tent-shape.
Z0/Z1 Magnitude
and
Z0M/Z1 Angle
is set to "Quad" and controls the polarizing current
Shape
is set to "Quad" and provides a method to correct
Shape
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
and settings, and if
Z0/Z1 Angle
settings. As such, enter the