PN 76.8820IM30-A
Tellabs 8820 Multi-service Switch Router System Installation
4-14
Installation
Connect 8820 MSR Alarm Outputs
Install Blank Panels
Connect 8820 MSR Alarm Outputs
The 8820 MSR chassis has a DB-25 connector for connections to an external alarm system.
Separate sets of alarm relay contacts are provided for the following alarm severities:
❑
Critical visual alarm
❑
Critical audible alarm
❑
Major visual alarm
❑
Major audible alarm
❑
Minor visual alarm
❑
Minor audible alarm
For each type of alarm, connect the common leads and either the normally open (N.O.) or
normally closed (N.C.) leads to the alarm annunciator or other external alarm system.
Whenever the 8820 MSR declares an alarm, that system will provide visual and audible
indications to alert office craftspersons of that condition.
Each set of relay contacts is Form C (dry contacts). The normal state of each set of relay
contacts is the no-alarm state. Therefore, be sure to connect the correct relay contacts (either
normally open or normally closed) to the alarm system. Refer to
for the DB-25 alarm connector’s signal pinouts.
Also connect an external alarm cutoff signal (ACO) to the 8820 MSR’s alarm connector. This
input cuts off 8820 MSR alarms from an external device.
