The operating and polarizing quantity are then used inside the directional element,
as shown in Figure 93, 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 93: 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 7 1MRK 506 382-UEN A
Current protection
198 Line distance protection REL650 2.2 IEC
Technical manual