Incorrect variance adjustment for Time Masters with degradation (loss of GPS)
Standard clarification required
TF Unique ID:
31 # IOP_2017/52
Discuss in Upcoming Meeting:
To discuss in WG10:
To send to Hubert for next 9-3 revision
Needs More Information:
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.
Assigned to IEC 61850-9-3
Updated by Vladan Cvejic over 2 years ago
- Subject changed from All masters adjust correctly (and conservatively) the ClockAccuracy field when degrading (loss of GPS) but they do not adjust th to Incorrect variance adjustment for Time Masters with degradation (loss of GPS)
- Category set to Standard clarification required
- Status changed from New to In Progress
- Standard(s) changed from 3-Sep to IEC 61850-9-3
- Discuss in Upcoming Meeting set to No
Updated by Carlos Rodriguez del Castillo 11 months ago
- Status changed from In Progress to Resolved
- Assignee set to Fred Steinhauser
- Proposal descriptions updated (diff)
Updated by Carlos Rodriguez del Castillo 23 days ago
- Needs More Information set to No