Distance Relay Setting Examples
GARD 8000 Distance Relay
RFL Electronics Inc.
8.2.4
GENERAL SETTINGS
According to the Stepped Distance example.
8.2.5
LINE PROTECTION SYSTEM SETTINGS
A typical DCB scheme uses three zones; Zone 1 as an independent underreach element, Zone 2 as a
forward pilot zone and Zone 4 as a reverse carrier start zone.
In the example below, only Zone 1 is enabled as an independent zone. Zone 2 and Zone 4 are only
used for the pilot scheme and consequently disabled in the Trip Mask below. Zone 3 is also not used in
this example.
Note that Zone 2 or Zone 3 can be selected as the pilot zone. This example is using Zone 2.
Zone 3 may be used as an independent time delayed backup zone for remote breaker failure. Zone 2
may also be used as a time delayed backup zone but as the setting should be made for pilot operation it
may not provide the required selectivity as a backup element.
8.2.5.1
TRIP MASK VERSUS ELEMENT ENABLE
Most functions have two enable settings. One in the Line Protection System Settings, which is the Trip
Mask. Another on the corresponding element setting page, which is the element enable setting. For
example, the Zone 2 element setting is on the page for “Distance Protection” “Zone 1 to 4.” The below
figure explains the difference between the Trip Mask and Element enable settings. The figure is uses
the example of Zone 2.
The Zone 2 element can have two functions; independent trip after set Zone 2 time delay, and/or pilot
operation through the selected pilot logic. The element itself (Zone 2 Enable on the Zone 1 to 4 page)
needs to be enabled for either of these functions to operate. However, the Line Protection System
Settings “Ground unit Z2” and “Phase unit Z2” can be disabled, and pilot operation will still take
place. Only if time-delayed independent Zone 2 trip is desired, should the Distance Protection System
settings be enabled.
Distance protection trip
Zone 2 Phase
Zone 2 Ground
Phase Units Z 2
Enable
Ground Units Z 2
Line Protection System
Settings
Distance Elements
Zone 1 to Zone 4
Zone 2 Enable
Pilot Logic
Enable
Enable
Zone 2 phase timer
Zone 2 ground timer
Yes
Yes
Yes
Figure 8-2. Trip Mask Enable and Element Enable (Directional Comparison Blocking)
August 1, 2009
8-14
973.334.3100
