Support #550
Incorrect variance adjustment for Time Masters with degradation (loss of GPS)
Start date:
Due date:
% Done:
0%
Estimated time:
ID:
31
Source:
IOP_2017/52
TF Unique ID:
31 # IOP_2017/52
WG10 Proposal:
Estimated Completion:
Discuss in Upcoming Meeting:
No
To discuss in WG10:
Short Proposal:
To send to Hubert for next 9-3 revision
Standard(s):
IEC 61850-9-3
Needs More Information:
No
Assigned TF:
Description
All masters adjust correctly (and conservatively) the ClockAccuracy field when degrading (loss of GPS) but they do not adjust the variance (offsetScaledLogVariance) correctly. This is a measured value that is used in the Best Master selection. Most clocks set the variance to 0 or 65535, or to a fixed (not computed) value.
Therefore, this field is unusable in the BMCA, a clock with a very poor variance could win over another clock that claims 0 variance.
IEC/IEEE 61850-9-3 should indicate specifically that the variance has to be adjusted.
Proposal descriptions
Assigned to IEC 61850-9-3