Micom P631, Technical Manual

Page: 214 / 638

3.27 Circuit Breaker Failure Protection (Function Groups CBF_1
and CBF_2)
The P631 features circuit breaker failure (CBF) protection functions. After a trip
command has been issued the CBF function checks that the circuit breaker has
actually been opened.
The CBF function group is repeatedly available so that a dedicated function may
be applied to each end on the protected object.
The following specifications apply to assigning the CBF protection functions to
the physical measured current values and the internal logical signals.
3.27.1 Assigning Transformer Ends
The currents to be monitored by the respective CBF function may be selected
using setting parameters:
Address Description Range of values
022 156 CBF_1: Select. meas. input End a
End b
022 157 CBF_2: Select. meas. input
3.27.2 Assigning Circuit Breakers
Each CBF_x function is permanently assigned to the respective circuit breakers
CBx. This concerns monitoring of the CB contact positions in conjunction with the
MAIN function of the protection unit. There are no specifications concerning the
assignment of circuit breakers to ends on the protected object.
3.27.3 Assigning the Trip Command
Which of the trip commands is to be used as a start criterion for the respective
CBF function may be selected by setting parameters:
Address Description Range of Values
022 202 CBF_1: Fct.assign. starting MAIN: Gen. trip signal 1
MAIN: Gen. trip signal 2
MAIN: Gen. trip signal 3
MAIN: Gen. trip signal 4
022 216 CBF_2: Fct.assign. starting
The functional range made available by the circuit breaker failure protection
function CBF_1 is documented in the following description. Function group CBF_2
provides the same functional range.
3.27.4 Enabling or Disabling the CBF Function
The activation of the function is enabled at CBF_1: General enable USER. If
this enabling function has been activated, CBF can be enabled or disabled via
setting parameters or through appropriately configured binary signal inputs. The
front panel HMI and the binary signal inputs have equal priority in this regard. If
only the function CBF_1: Enable EXT is assigned to a binary signal input, then
CBF will be enabled by a positive edge of the input signal and disabled by a
negative edge. If only the parameter CBF_1: Disable EXT has been assigned
to a binary signal input, then a signal at this input will have no effect.
P631 3 Operation
3-158 P631/EN M/R-11-C // P631-310-650