Date Code 20181001 SEL-3031 Instruction Manual
Performance Monitoring, Testing, and Troubleshooting
Self-Test
5.5
The RBAD bit is generated by the output of the RBAD timer. The RBAD timer is
driven by the ROK signal. RBAD is the recommended bit to indicate communications
alarms. Typically, a communications outage of two seconds or greater is considered an
alarm condition. RBAD should be set on both M
IRRORED BITS device to the maximum
length of outage before declaring an alarm.
The CBADPU setting is generated from the unavailability of the M
IRRORED BITS
channel. For example, if RBADPU is set to 2 seconds and the longest channel
disruption was 1 second out of every second and this occurred every 2 seconds, RBAD
would not assert. RBAD would not assert because M
IRRORED BITS is not disrupted for
longer than 2 seconds at any time. Relay Word bit CBAD and the CBADPU setting
solves this problem. To set CBADPU there are two good options. The first option is to
set it to 2000. This is a common value used based upon spread spectrum radio use in
the field. The CBAD Relay Word bit will assert when the unavailability of the channel
exceeds 0.02.
The other method in setting CBAD is to let the radio link run for a period of time and
monitor the performance. After reviewing a month of unavailability you will be able to
set CBADPU above the unavailability value.
The proper setting and use of CBAD and RBAD is important to report when the
communications link has failed or has become intermittent enough to cripple proper
communication. Over time, many issues can occur to cause a bad or intermittent radio
link. Items such as tree growth, new building construction, or another radio added at
the site or in the path of the current radio link. It is important to take CBAD and RBAD
and use them in the relay to trigger an alarm condition through an output contact or
have the SCADA system detect the alarm. Line-of-site radio paths can experience
adverse conditions over time and it is critical to constantly monitor the radio
performance to keep the availability numbers as high as possible.
Self-Test
All self-tests are described in Table 5.1. If all diagnostic tests are passed, the ENABLED
LED is on, the ALARM LED is off, and the contact output is open. If the device is
disabled, the ENABLED LED is off, the ALARM LED is illuminated, and the contact output
is closed.
Table 5.1 Device Self-Tests (Sheet 1 of 2)
Self-Test Description
SER
Message
Alarm
LED
Alarm
Contact
FPGA Version
Mismatch
Fails if FPGA registers do not match
expected.
Yes On Closed
Data RAM Performs read/write tests on each
section of Data RAM.
Yes On Closed
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