RFL Electronics GARD 8000 - Current Differential Protection

Applications
GARD 8000 SYS RFL Electronics
May 1, 2013 2-25 973.334.3100
The distance protection contains its own functional logic but a large number of logic bits are available
for customized functions in the System Logic. A detailed description of the distance protection is
found in the Distance Protection Manual.
2.10 CURRENT DIFFERENTIAL PROTECTION
A Current Differential Protection Module can be integrated in the GARD 8000 System. Using one 64
kbps channel, the current differential relay can use the same communication link as the teleprotection
system module, or it can have its separate channel interface.
Duplicating the highly successful RFL 9300 measuring principle with its high speed operation, the
GARD 8000 current differential protection provides added flexibility and enhanced functionality:
 While still extremely simple to set, extended setting ranges are made available for increased
system fault current coordination
 Transient block logic for added security at external fault clearing with ct errors
 Adjusts for different ct ratios by setting
 High speed trip; ½ cycle minimum, 1 cycle typical
 Is completely unaffected by channel delay errors up to +/- 4 ms (5 ms for 50 Hz) as may be
caused by asymmetric transmit and receive channels
 Two or three-terminal versions
 Hot/stand-by redundant channel operation
 Optional single pole trip logic
All Current Differential Protection logic is contained in the functional module but a large number of
logic bits are available for customized logic in the System Logic. A detailed description of the Current
Differential Protection is found in the Current Differential Protection section of this manual.
2.11 POWER LINE CARRIER
The Power Line Carrier (PLC) module in the GARD 8000 System implements the functionality of the
RFL 9785 ON/OFF PLC and the RFL 9780 FSK PLC, all in one device. FSK or ON/OFF operation is
selectable and the DSP based transmitter and receiver allows full frequency programmability in the
range 30 to 500 kHz.
The setting options include:
a. Selectable FSK or ON/OFF operation
b. Transmit frequency 30 to 500 kHz
c. Programmable receive bandwidth and frequency shift
d. Adjustable logic timers
e. Unblock, blocking, permissive, transfer trip or phase comparison applications
Power Line Carrier features include:
 Channel monitoring
 Built-in check back function; set for periodic check and/or remotely activated
 Extensive Sequence of Event Reporting
 Built-in reflected power measurement