Instruction Manual

57
Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Technical Support
Link Message repeating:
➤ When a feeder is powered up to a low load condition, the SEL-RP50
wireless repeaters are in a sleep state and do not continually operate.
In this state they periodically turn on the radio to listen for Link sig-
nals, and then go back to sleep to save energy. The system is
designed to eventually capture an incoming Link message and then
synchronize the wake up timer.
➤ Once synchronized, the SEL-RP50 will wake up regularly in time to
catch the incoming link message, and then retransmit the link mes-
sage to the next device. This synchronization can take up to 30 min-
utes per SEL-RP50.
➤ A system with the maximum of five SEL-RP50s on the same Unit ID
could take several hours for the SEL-FR12 LINK LED to illuminate.
This delay is shorter if the SEL-RP50s nearest the feeder source
(substation).
➤ When the SEL-RP50 is in the Awake mode there is no synchroniza-
tion delay because the wireless receiver is on all of the time. If the
load current later drops below the level needed to remain in the
Awake state, the SEL-RP50 will remember the synchronization and
should be able to keep transmitting link messages without needing to
resynchronize.
➤ If the line current drops below the sleep state level, the SEL-RP50
shuts down, and when sleep level current later comes back, it must
resynchronize.
➤ If the system is fully synchronized but the SEL-FT50 loses current
for over one minute, it will stop transmitting Link messages. Any
SEL-RP50s in the sleep state will lose synchronization. When the
SEL-FT50 load current reappears and it resumes transmitting Link
messages, all SEL-RP50s that are in sleep mode will need to resyn-
chronize.
➤ During all of these resynchronization cases, the SEL-FT50/
SEL-FR12 system still responds to faults, if the devices are installed
on the proper phase, as shown in Figure 35.
Technical Support
We appreciate your interest in SEL products and services. If you have questions
or comments, please contact us at:
Schweitzer Engineering Laboratories, Inc.
2350 NE Hopkins Court
Pullman, WA, 99163-5603 U.S.A.
Tel: [phone]
Fax: [phone]
Internet: selinc.com/support
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