How high impedance is calculated

High impedance is evaluated by day, per leg. All criteria apply to each leg. If there is high impedance, an alert is created for that meter/leg at the end of the day. The next day high impedance is evaluated again, and if high impedance is detected another alert is created.

There is either an alert message for the day or there is not. Alarms are raised for a service point and phase and are considered active in the Itron system until closed by the user through the API or the user interface.

In the user interface, you can use a filter to show only service points where the High Impedance Threshold is exceeded for a specified number of days within a specified date range (by selecting that date range), for example >= two days within a seven day period. For more information about filtering in the user interface, see Filtering the alarms table.

Calculation

When load current changes are above a set current threshold, impedance is calculated only if the change in voltage is in the opposite direction to the change in current.

For days when the number of load changes is greater than or equal to the set minimum number of load changes on a leg, the median impedance is calculated. If the median impedance calculated for the day exceeds the High Impedance Threshold, an alert is created.