Description of Operation
GARD 8000 Distance Relay
RFL Electronics Inc.
9.2
NON-PILOT AND PILOT SCHEMES
9.2.1
STEPPED DISTANCE
The stepped distance logic is always active. The Stepped Distance protection scheme can be selected
alone or as a complement to any of the other schemes. Operation of the Stepped Distance scheme is
based on the time delay of the different zones; therefore, communication is not required.
Phase A Zone n Unit
Phase B Zone n Unit
Phase C Zone n Unit
Phase AB Zone n Unit
Phase BC Zone n Unit
Phase CA Zone n Unit
0
30 ms
ZnG
delay
0
ZnP
delay
0
Zn Ph PU/Zone n Phase Units Pick Up
Zn G PU/Zone n Ground Units Pick Up
Enable ZnG
Enable ZnP
Zone n Fault
Figure 9-10. Zone Logic
Ser comp block (option)
Out-of-step Block
Enable Z1 OSB
Enable Z2 OSB
Enable Z3 OSB
Enable Z4 OSB
Zone 1
Step
Distance
Zone 2
Step
Distance
Zone 3
Step
Distance
Zone 4
Step
Distance
LOP Block Trip
Step Distance
Zone 1 Fault
Zone 2 Fault
Zone 3 Fault
Zone 4 Fault
Figure 9-11. Stepped Distance Logic
August 1, 2009
9-15
973.334.3100
