638   Conflict with part 5 transfer time

Created: 17 Apr 2009

Status: Triage

Part: Part 10 (2005)

Links:

Page: 39

Clause: 7.2.1

Paragraph:

Category: Issue for edition 2 of this part

Issue

In IEC 61850-5, section 13.4, transfer time = ta + tb + tc. In this section, ta doesn't seem to include "input processing time" (input signal conditioning - e.g., debouncing, sampling, etc.). Also, tc doesn't seem to include "output processing time" (time required for output signal activation - e.g., contact delays, I/O scan rate, etc.).

But reading section 7.2.1 of IEC 61850-10, I understood that input/output processing times are included in the transfer time.

Proposal

The standard should clarify if input/output processing times are included or not in the transfer time.
For instance, considering performance class P2 that requires 3 ms of transfer time for a trip (IEC 61850-5), according IEC 61850-1, 40% of 3 ms (1.2 ms) would be the limit time for instance, since GOOSE message arrives a subscriber until the physical output contact closes. Is this true? If this is true, than maybe you should correct IEC 61850-5 definition of transfer time at section 13.4, to include the input/output processing times.