Alarm flooding prevention in SCADA systems - Step-by-Step Execution

Process Flow - Alarm flooding prevention

Alarm Triggered

↓

Check Flood Threshold

↓

Suppress

↓

Log Alarm

↓

End

When an alarm triggers, the system checks if too many alarms happened recently. If yes, it suppresses new alarms to avoid flooding. Otherwise, it sends and logs the alarm.

Execution Sample

SCADA systems

alarm_count = 0
threshold = 3
if alarm_count >= threshold:
    suppress_alarm()
else:
    send_alarm()
    alarm_count += 1

This code checks if the number of alarms reached a limit. If yes, it stops sending new alarms; if no, it sends the alarm and increases the count.

Process Table

Step	alarm_count	Condition (alarm_count >= threshold)	Action	Result
1	0	0 >= 3 is False	send_alarm(), alarm_count += 1	alarm sent, alarm_count=1
2	1	1 >= 3 is False	send_alarm(), alarm_count += 1	alarm sent, alarm_count=2
3	2	2 >= 3 is False	send_alarm(), alarm_count += 1	alarm sent, alarm_count=3
4	3	3 >= 3 is True	suppress_alarm()	alarm suppressed, alarm_count=3
5	3	3 >= 3 is True	suppress_alarm()	alarm suppressed, alarm_count=3

💡 Alarm count reached threshold; alarms are suppressed to prevent flooding.

Status Tracker

Variable	Start	After 1	After 2	After 3	After 4	After 5
alarm_count	0	1	2	3	3	3

Key Moments - 2 Insights

Why does the alarm stop sending after alarm_count reaches 3?

Because the condition alarm_count >= threshold becomes True at step 4 (see execution_table row 4), triggering suppression instead of sending.

Does alarm_count increase when alarms are suppressed?

No, alarm_count only increases when alarms are sent (see execution_table rows 1-3). When suppressed (rows 4-5), alarm_count stays the same.

Visual Quiz - 3 Questions

Look at the execution table, what is alarm_count at step 3?

A 1

B 2

C 3

D 0

💡 Hint

Check the 'alarm_count' column in execution_table row 3.

At which step does the condition alarm_count >= threshold become True?

A Step 4

B Step 2

C Step 3

D Step 5

💡 Hint

Look at the 'Condition' column in execution_table rows 3 and 4.

If threshold was increased to 5, what would happen at step 4?

A Alarm_count would reset to 0

B Alarm would be suppressed

C Alarm would be sent and alarm_count incremented

D System would crash

💡 Hint

Compare the condition alarm_count >= threshold with threshold=5 at step 4 in execution_table.

Concept Snapshot

Alarm Flooding Prevention:
- Track number of alarms sent (alarm_count).
- Set a threshold limit.
- If alarm_count >= threshold, suppress new alarms.
- Otherwise, send alarm and increment alarm_count.
- Prevents too many alarms at once, reducing noise.

Full Transcript

Alarm flooding prevention means stopping too many alarms from sending at once. The system counts alarms sent and compares to a set limit. If the count reaches the limit, new alarms are stopped (suppressed). Otherwise, alarms are sent and the count increases. This keeps the alarm system from overwhelming users with too many alerts at the same time.