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Support #550

Incorrect variance adjustment for Time Masters with degradation (loss of GPS)

Added by Herbert Falk almost 2 years ago. Updated 7 months ago.

Status:
Resolved
Priority:
Normal
Category:
Standard clarification required
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:

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

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