928   Explicit Declaration of Semantics of the Pos (position) Attribute

Created: 03 Oct 2012

Status: In Force (green)

Part: Part 7-4 (2010; Edition 2)

Links:

Page: 117

Clause: 6

Paragraph:

Category: No impact on this part

Issue

The relationship between on and off and the physical attributes of open and closed for the position of switches is not explicitly defined in IEC 61850. While it might be said that the meaning is obvious that "on" = "closed" because naturally when power is on a switch is closed, we should avoid ambiguity. In the IEC 60870-6 specifications, where on=closed is stated explictly, even in this case some implementations made a different interpretation anyway.

The only places where it is currently described is in the discussion of a breaker sequence in 7-1 (Clause 9.4) where a reference to "off" and "open" appear in the same sentence in the description of a breaker opening sequence and in the Data Semantics Table 10 in 7-4 for the EnaOpn and EnaCls attributes where the terms “Open/Off” and “Close/On” are used in describing the checks done in processing the EnaOpn and EnaCls attributes.

Proposal

I propose that the data semantics table 10 in clause 6 of 7-4 beginning on page 117 be updated so that the semantics for the Pos attribute explictly declares the equivalence of "off = open" and "on = closed" for switch positions.