A-14 Issue 4 February 1997
363-208-011
Applications
COT Alarms and Parallel Telemetry
Office Alarms
COT alarms are system defined as critical, major, minor, and power minor. Each is
brought out to the MDF/IDF cross connect frame for connections to the office
audible and visual alarm systems. Their connections to the
SLC
-2000 system are
through the TS1 block interfacing with the ATU which contains relays for each
alarm condition. The critical alarms are fail safe against power failures and are
activated even if the ATU loses power.
Parallel Telemetry
The parallel telemetry system provides relay closures for alarm and status
conditions to an operations center.
Alarms
Individual closures for critical and minor alarms reflect the office alarms and are
activated when an alarm condition is detected.
Power Minor Alarm This alarm is used to detect the loss of commercial ac power at
the RT and is not considered service affecting when the RT
power system has battery back-up.
Minor Alarms Minor alarms are classified as not service affecting and are used
to detect the failure of a single rectifier in the power system, a
single ringing generator in a protected ringing system, or a fan
failure. Minor alarms also apply to service affecting failures
affecting less than 23 customers or the failure of any protected
synchronization or transmission equipment.
Major Alarms An example of a service affecting external major alarm is the
loss of the entire ringing supply to the RT system. Major alarms
also apply to service affecting failures affecting more than 23 but
less than 128 customers or four DS1s, or loss of both DS1 syn-
chronization references. Major alarms also include non service
affecting failures that could mask other service affecting failures,
such as, the failure of the DCC.
Critical Alarms Critical alarms are defined as failures which put out of service a
group of 128 or more customers, or more than four DS1s or any
unprotected synchronization equipment failure.
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