ABB RED650 - Page 204

The operating and polarizing quantity are then used inside the directional element,
as shown in Figure 86, in order to determine the direction of the earth fault.
STRV
0.6 * IN>DIR
STFW
-RCA -85 deg
40% of
IN>DIR
IN>DIR
RCA
65°
U = -3U
pol 0
I = 3I
op 0
RCA +85 deg
RCA -85 deg
Characteristic
for STRV
Operating area
Operating area
Characteristic
for STFW
Characteristic for reverse
release of measuring steps
Characteristic for forward
release of measuring steps
-RCA +85 deg
IEC11000243-1-en.ai
IEC11000243 V1 EN-US
Figure 86: Operating characteristic for earth-fault directional element using
the zero sequence components
The relevant setting parameters for the directional supervision element are:
• The directional element will be internally enabled to operate as soon as Iop is
bigger than 40% of IN>Dir and the directional condition is fulfilled in the set
direction.
• The relay characteristic angle AngleRCA, which defines the position of
forward and reverse areas in the operating characteristic.
The directional comparison will set the output binary signals:
1. STFW=1 when operating quantity magnitude Iop x cos(φ - AngleRCA) is
bigger than setting parameter IN>Dir and directional supervision element
detects fault in forward direction.
2. STRV=1 when operating quantity magnitude Iop x cos(φ - AngleRCA) is
bigger than 60% of setting parameter IN>Dir and directional supervision
element detects fault in reverse direction.
Section 8 1MRK 505 394-UEN A
Current protection
198 Line differential protection RED650 2.2 IEC
Technical manual