Service manual

Alarm sequence 1
B-3
B
◆
Alarm sequence 1
Alarm states in
sequence 1
The following figure shows the various states in alarm sequence 1.
Behavior The following table shows the behavior of LEDs and relays in alarm sequence 1:
Alarm sequence 1
characteristics
The following table shows the characteristics of alarm sequence 1:
Reference Alarm sequence 1 complies with the British Telecom requirements.
0
No Alarm
1
Alarm
without Attn.
Alarm active
Alarm inactive
2
Alarm
with Attn.
3
No Alarm
with Attn
Alarm active
Alarm inactive
Receive
Attention
Receive
Attention
Alarm Sequence 1
Active alarms require attention.
Alarms with attention require a new
attention to be removed.
Alarm LED A = A alarm(s) in state 1 or 2
Alarm LED B = B alarm(s) in state 1 or 2
Rec. Attn. LED = No alarms in state 1
AND alarm(s) in state 2 or 3
A relay = A alarm(s) in state 1
B relay = B alarm(s) in state 1
C relay = C alarm(s) in state 1
Rec. Attn. Relay = alarm(s) in state 2 or 3
Clear relay = alarm(s) in state 3
LED or relay Indication
Alarm LEDS Active alarms.
Alarm relays Active alarms with attention.
Receiving Attention relay The presence of alarms, active or inactive, that
have been given attention.
Clear relay The presence of inactive alarms that were given
attention when they were active.
Alarm sequence 1 characteristics
Relays indicate unserviced alarms Yes
Relays indicate all alarms No
One relay indicates alarms with attention Yes
One relay indicates cleared alarms with attention Yes
Tight control over alarms with attention Yes
Clear relay indication of alarms with or without attention No
Relays are used to switch to backup systems during alarm
conditions
No