7SR11 & 7SR12 Description Of Operation
©2012 Siemens Protection Devices Limited Chapter 1 Page 60 of 76
The ‘Reclaim time’ will start each time a Close Pulse has timed out and the CB has closed.
Where a protection pickup is raised during the reclaim time the relay advances to the next part of the reclose
sequence.
The relay goes to the Lockout state if the CB is open at the end of the reclaim time or a protection operates during
the final reclaim time.
Open CB Pulse
The duration of the CB open pulse is user settable to allow a range of CBs to be used.
The CB open pulse must be long enough for the CB to physically open.
CB Travel Alarm
The CB Open/CB Closed binary inputs are continually monitored to track the CB Status.
The CB should only ever be in 3 states:
CB Status CB Open
binary input
CB Closed
binary input
CB is Open 1 0
CB is Closed 0 1
CB is Travelling
between the
above 2 states
0 0
The Relay goes to Lockout and the CB Alarm output is given where the Travelling condition exists for longer than
the CB Travel Alarm setting.
An instantaneous CB Alarm is given for a 1/1 state – i.e. where the CB indicates it is both Open and Closed at the
same time.
Hot Line In/Out
When ‘Hot Line’ is enabled all auto reclose sequences are inhibited and any fault causes an instantaneous trip to
lockout.
Figure 4-3 Logic Diagram: Circuit Breaker Status
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