Siemens SIPROTEC 5 Manual page 419

A new average value is formed every 10 min at hh:00, hh:10, hh:20, hh:30, hh:40, hh:50. All measured
values obtained during the last 5 min are used to form the average value.
If these settings are changed to 11:03:25, for instance, the average values are first reset and "---" appears in
the display. The 1st average value is then formed at 11:10:00.
SIPROTEC 5, Fault Recorder, Manual
C53000-G5040-C018-5, Edition 11.2017
Measured and Energy Values
9.5 Average Values
419