Cb/Circuit Position Monitoring; External Cb Fail Input (Ext 87Cbf); Figure 5-3 Logic Diagram: Cb Position Monitoring; Figure 5-4 Logic Diagram: Ext 87Cbf - Siemens 7SR23 DAD Manual

Chapter 1) 7SR23 DAD Description Of Operation

5.2.1 CB/Circuit Position Monitoring

The position of up to 12 CBs can be monitored utilising either the IEC61850 comms or wiring between binary
inputs of the 7SR23 and CB auxiliary switches, in effect producing a replica of the busbar.
Auxiliary switches can be connected either as a single CB open, a single CB close or using two auxiliary switches
as a pair i.e. switches for both the CB open and CB closed positions. When two auxiliary switches from a CB are
monitored an alarm/inhibit can be provided for the CB 'Don't Believe it' (DBI) state.
Figure 5-3 Logic Diagram: CB Position Monitoring

5.2.2 External CB Fail Input (Ext 87CBF)

An external CB Fail initiate can utilise the CB Position monitoring feature. When an external protection operates
but then identifies a failed CB condition, an output signal can be provided. The output signal can be connected to
a binary input programmed as Ext 87CBF. Outputs are energised for any circuit breaker that is connected to the
faulted busbar and is identified as being in the closed position.
Figure 5-4 Logic Diagram: Ext 87CBF
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