A sum alarm can be seen as a collection of alarms that have one or several common denominators. The conditions you use to filter which alarms the sum alarm monitors are the same conditions you use to filter the Alarms pane or an Alarm View. You can use wildcards when setting up filter conditions. For more information, see Filter Condition Wildcards .
For example, when an alarm is triggered you want to light a red indication lamp. Instead of connecting all alarms in the system to the indication lamp, you create a sum alarm and connect it to the indication lamp. You reduce the amount of alarms by configuring the sum alarm to only trigger when alarms with a certain priority and category are triggered.
In a multi-server system, a Sum Alarm created on the a parent server functions as a container for alarms triggered on the child servers. For example, a Sum Alarm created on an Enterprise Central functions as a container for all alarms triggered in the system:
on the Enterprise Servers connected to the Enterprise Central
alarms on the Automation servers connected to those Enterprise Servers
The advantage of creating the sum alarm on the parent server is that you do not need to create separate sum alarms for child server.