269 PTRC and Switch on to faultCreated: 08 Dec 2005 Status: In Force (green) Part: Part 7-4 (2003) Links: Page: 30 Clause: 5.4.21 Paragraph: Category: Issue for edition 2 of this part Issue If an open circuit breaker is closed, it may switch on to a fault, e.g. if a mobile earth connection for maintenance is connected or any other permanent fault exist which has happened on the disconnected part of the line, busbar or cable. In this case, any related protection function has operate/trip immediately without any time delay. There is no LN in the standard (7-4) defined for this functionality. Proposal Both the Str (start) and the Op (operate) of all connected protection LNs are available (subscribed)in the related PTRC. Normally the Tr (trip) is issued by PTRC based on a logical OR of all the Op's including all the individual delays of the protection functions. In case of "Switch on to fault" a logical OR of all Str's shall issue the Tr (trip). The "switch on to fault" situation may be simply defined if the breaker was longer open then a predefined time:
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