SS Scalar Sum The sum of the absolute values of the local charge and the remote
charge (actually RMS current equivalent to charge).
Local Remote Scalar
Examples
Charge Charge Sum
Ex. 1 -6A +4A 10A
Ex. 2 -4A +6A 10A
Ex. 3 +4A +6A 10A
The Scalar Sum is equivalent to the “restraint current” in a conventional
current differential relay. The arithmetic sum defined earlier and the
scalar sum taken together determine whether or not the RFL 9300 Re-
lay Charge Comparison algorithm decides to trip.
SV Supervisor Controller This is a front panel module on the 9300 which controls the routing of
messages between all other modules of the 9300. It also contains 9300
system logic.
SWID Software Identification The SWID is a software identification number which indicates the revi-
sion of the software in the 9300. There are up to eight SWID numbers
for each 9300 as follows: 1 for each Communications Controller, 1 for
the Supervisor Controller, 4 for the Phase Controllers, and 1 for the
Display Controller. See paragraph 6.1 for more information.
TOC Time Overcurrent Time Overcurrent
TX Transmitter The 9300 transmitter.
TX/RX Transmit/Receive Transmit/Receive
UGD Underground Underground
UHS Ultra-High Speed The UHS is an algorithm which works in parallel with the charge com-
parison algorithm and weak feed trip algorithm defined below. The
UHS operates whenever there is moderate or high current, above +12A
peak for 2-ms or more. A message is sent to the remote terminal to
command a trip unless there is high negative current. For high current
faults, the UHS provides faster tripping than the charge comparison.
UHST Ultra High Speed Trip Ultra High Speed Trip
WCM Weak Current Message Weak Current Message
WFT Weak Feed Trip The WFT is an algorithm which supplements the charge comparison
for internal faults where one terminal contributes very little or no fault
current. There is not a significant half-cycle charge measured at the
weak terminal for this condition. WFT works by detecting a low magni-
tude current at the local terminal, coincident with moderate or high cur-
rent at the remote terminal.
WR Write Write
RFL 9300 RFL Electronics Inc.
May 5, 2002 30 - 5 (973) 334-3100
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