CHAPTER 7: PROTECTION GROUPED PROTECTION ELEMENTS
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 197
RCA
Range: 30 to 90° in steps of 1
Default: 85°
This setting specifies the characteristic angle (similar to the “maximum torque angle” in
previous technologies) of the phase distance characteristic for the forward and reverse
applications. In the non-directional applications, this setting defines the angle of the
forward reach impedance. The reverse reach impedance in the non-directional
applications is set independently. The setting is an angle of reach impedance as shown
in the distance characteristic figures shown earlier. This setting is independent from the
Directional RCA setting, the characteristic angle of an extra directional supervising
function.
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 non-directional zone. 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 of the non-directional
zone. This setting does not apply when the zone direction is set to “Forward” or
“Reverse.”
Comparator Limit
Range: 30 to 90° in steps of 1
Default: 90°
This setting specifies the shape of the operating characteristic. In particular, it produces
the lens-type characteristic of the mho function and a tent-shaped characteristic of the
reactance boundary of the quadrilateral function. If the mho shape is selected, the same
limit angle applies to both the mho and supervising reactance comparators. In
conjunction with the mho shape selection, the setting improves loading 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.
Directional RCA
Range: 30 to 90° in steps of 1
Default: 85°
This setting specifies the characteristic angle (or maximum torque angle) of the
directional supervising function. If the mho shape is applied, the directional function is
an extra supervising function as the dynamic mho characteristic is itself directional. In
conjunction with the quadrilateral shape, this setting defines the only directional
function built into the phase distance element. The directional function uses the memory
voltage for polarization. This setting typically equals the distance characteristic angle
specified by the
RCA setting.
Directional Comparator Limit
Range: 30 to 90° in steps of 1
Default: 85°
This setting specifies the comparator limit angle for the directional supervising function.
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