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I.L. 40-386.3
current ground-fault recognition at the remote terminal, allows immediate tripping to
take place at the terminal.
1.4.4
Self-checking Software
REL 301/302 continuously monitors its ac input subsystems using multiple A/D con-
verter calibration-check inputs, plus loss-of-potential and loss-of-current monitoring.
Failures of the A/D converter, or any problem in a single ac channel which unbalances
non-fault input, causes an alarm. Self-checking software includes the following func-
tions:
a. Digital Front-end A/D Converter Check
b. Program Memory Checksum
Immediately upon power-up, the relay does a complete EPROM checksum of program
memory. After power-up, the REL 301/302 continually computes the program memory
checksum.
c. Power-up RAM Check
Immediately upon power-up, the relay does a complete test of the RAM data memory.
d. Non-volatile RAM Check
All front-panel-entered constants (settings) are stored in non-volatile RAM in three identical
arrays. These arrays are continuously checked by the program. If any of the three array
entrees disagree, a non-volatile RAM failure is detected.
1. 5.
UNIQUE REMOTE COMMUNICATION PROGRAM (RCP)
Two types of remote interface can be ordered.
• RS 232C for single point computer communication.
• INCOM
A special software program (RCP), is provided for obtaining or sending, setting, and
target information from or to the REL 301/302. The REL 301/302 front panel shows
two fault events (last and previous), but with the remote communications, 16 fault
events and 16 records of intermediate target data can be obtained and stored. Each
record of the intermediate target data contains 8-cycle information (1 prefault and 7
post-fault), with 7 analog inputs and 24 digital data (at the sampling rate of 8 per cy-
cle). Refer to RCP manual for detailed information. (See I.L. 40-603.)
1-6
®
for local network communication.
(10/94)
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