Circuit Breaker Failure (50Bf); Figure 4-6 Logic Diagram: Circuit Breaker Fail Protection (50Bf) - Siemens 7SR105 Rho User Manual

4.6

Circuit Breaker Failure (50BF)

The circuit breaker fail function has two time delayed outputs that can be used for combinations of re-tripping or
back-tripping. CB Fail outputs are given after elapse of the 50BF-1 Delay or 50BF-2 Delay settings.
The circuit breaker fail protection time delays are initiated either from:
An output Trip Contact of the relay (MENU: OUTPUT CONFIG\BINARY OUTPUT MATRIX\Trip
Contacts), or
A binary input configured 50BF Ext Trip (MENU: INPUT CONFIG\BINARY INPUT MATRIX\50BF Ext
Trip).
CB Fail outputs will be issued providing any of the 3 phase currents are above the 50BF Setting for longer than
the 50BF-n Delay setting – indicating that the fault has not been cleared.
Both 50BF-1 and 50BF-2 can be mapped to any output contact or LED.
Operation of the CB Fail elements can be inhibited from:
Inhibit 50BF
50BF Element
Enabled
Inhibit 50BF
50BCL CB Fail
Trip Contact
≥
1
50BF Ext Trip
50BF Mech Trip
&
CB Closed
50BF Setting
I
A
I >
B
I
C
50BF-I4 Setting
I
>
G
Figure 4-6
©2018 Siemens Protection Devices
A binary or virtual input.
50BF CB Faulty
&
&
&
≥
1
&
≥
1
Logic Diagram: Circuit Breaker Fail Protection (50BF)
7SR105 Rho Description of Operation
50BF-1 Delay
&
50BF-2 Delay
&
≥
50BF-n-1
1
≥
50BF-n-2
1
Chapter 1 Page 42 of 57