1845   SwModKey seems to overwrite the CheckCondition.interlockCheck

Created: 14 Sep 2022

Status: Discussion (red)

Part: Part 7-4 (2020; Edition 2.1)

Links: #1782 Clarification of when to ignore the check bits

Page: Table 45, 61

Clause: 6.3.3

Paragraph: 6.3.3

Issue

The DataObject SwModKey, specified in the LNClass LLN0 and CSWI is defined as determining if the interlocking check is bypassed during an operate request.
The Service Parameter Check.interlockCheck specifies already that the interlockCheck has to be performed (default) or has to be bypassed (emergency).
Based on Tissue #1782, the Checks are performed as requested as soon as the operational state allows the bypass.

Proposal

Modify the definition of SwModKEy based on the use case need of defining how local operation are performed (with interlock check, or temporarily with bypassing the interlock check).
Consider defining SwModKey at the IHMI LN, in case the IHMI needs to know if the Operate Requests are beeing issued with Check.interlockCheck = true (default) or = false (temporarily).
When SwModKey is present in the CSWI or in LLN0, is represents the SwModKey value at the IED, and indicates how local operate services will be issue (with Interlocking Check (default), or without).
consider limiting the SPC.cltModel to status only, as the SwModKey is either aquired
- via binary input
- via a real key
- via a button
- via a software button
There is no need to Operate the SwModKey.