RFL Electronics GARD 8000 - Figure 13-15. Current Differential Relay General Settings

Current Differential Relay
GARD 8000 SYS RFL Electronics
June 20, 2014 13-16 973.334.3100
Figure 13-15. Current Differential Relay General Settings
General Settings Definitions:
Module Service
This enables or disables the module. When disabled it is removed from the logic and communications
busses.
Last Trip Close Timer (100-5000 inc 100)
This sets the time the relay must be in a non-tripped condition in order to record a new trip event and
make the information available in the last trip status page (section 13.4.6).
The setting must be between 100ms and 5s (inclusive) in increments of 100ms.
Guard Before Trip
The guard before trip function adds an extra level of security by requiring a clean and stable
communications channel prior to allowing any trip messages through. This function may be disabled if
the speed of reestablishing protection is more important than the added security the feature provides.
Terminals
Select 2 terminal or 3 terminal operation.
Hot Standby Mode
This enables a backup Comms Channel.
Hot Standby Preferred Channel
Check to select channel 1 or 2 for Hot Standby Mode. Note that hot standby will communicate on the
selected channel until that channel fails and then switch to the unselected channel.
Line Connections
Single Pole Tripping
For relays purchased with the single pole option this is used to enable or disable the single pole
features. Disabling single pole makes the relay function as a three pole relay.
CT Saturation Block
This function detects ct saturation by looking at the waveform. When enabled, the detector disables
outfeed trip for a period of 250ms in 60Hz mode and 300ms in 50Hz mode. Outfeed refers to the
currents having opposite polarity in the two line ends, i.e. current is flowing out of the line. This
function prevents possible misoperation for sensitive settings when a substantial differential current
could be calculated for external faults due to ct errors. See Section 13.5.1.2.
Phase Comparison Block
Check to enable blocking of trips when the remote and local currents remain 180 degrees out of phase,
functionally emulating a phase comparison measurement instead of a current differential measurement.
This function disables outfeed tripping permanently and can be used when abnormally large ct errors
can be expected. See Section 13.5.1.2.