Description of Operation
GARD 8000 Distance Relay
RFL Electronics Inc.
Figure 9-5. Reactance Characteristic (II)
Figure 9-5 shows the Reactance characteristic under a no-load system (without remote-end current
infeed to the fault). In this case, the fault is seen by the relay to be rotated by an angle gamma due to
the lack of homogeneity on the system. The tilt angle changes the characteristic from C1 to C2,
avoiding overreach of the relay during the preset tilt time, and allowing the adjacent protection
elements to clear the fault. Angle gamma is calculated by the relay from the line and source
impedances.
I
F
Phase current
Ieq
Equivalent current: Ieq=I
F+I0(k0-1)
Phase voltage
V
F
RF
Ground fault resistance
IF
Current through ground fault resistance
Z1F Set
reach
August 1, 2009
9-8
973.334.3100
