A shunt variable is a binary value that works as an on/off switch for the alarm.
When an alarm is shunted the alarm stops evaluating, that is, no longer listens to the alarm trigger that can cause the alarm to change state. If the alarm is in Normal or Acknowledged state when it is shunted, the alarm changes to Disabled state. If the alarm is in Alarm or Reset state when it is shunted, it remains in that state. When you acknowledge a shunted alarm it changes to Disabled state. When a shunted alarm is unshunted, the alarm starts evaluating again, that is, starts to listen to the alarm trigger that can cause the alarm to change state.
You can invert the shunt variable, which means that the alarm is shunted when the shunt variable is set to False.
You can set two shunt variables for every type of EcoStruxure Building Operation alarm. You combine the two shunt variables by using a shunt operator with AND or OR logic instead of writing a program to handle the logic.
When the flow from a pump exceeds the configured limit, an alarm is triggered. The alarm is only relevant if the pump is switched on. To enable the alarm only when the pump is switched on, you set a shunt variable on the alarm.
When a pump is switched off, an alarm is triggered. You can invert the shunt variable so that the alarm is enabled when the pump is switched on.