Micom P721, Technical Manual

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User Guide P72x/EN FT/C21
MiCOM P721/P723 Page 31/38
2.8.7 CIRCUIT BREAKER FAILURE submenu
With the CB Fail submenu, circuit breaker failure can be detected and associated
parameters can be set.
AUTOMAT. CTRL
CB Fail
Heading of the CB Fail submenu.
CB Fail ?
Yes
Selection of the circuit breaker failure function.
If Yes is selected, the following menu is displayed:
If No is selected, the CB Fail function is inactive.
I Diff < =
0.1
In
Selection of the undercurrent differential protection
threshold associated to the CB failure detection function,
from 0.01In to 1In (step 0.01In).
V Diff < =
5V
P723 with voltage input selection only.
Selection of the undercurrent differential protection
threshold associated to the CB failure detection function,
from 0.5V to 200V (step 100mV).
CB Fail Time
tBF
40 ms
Selection of the circuit breaker failure time delay from
10ms to 10s (step 10ms).
2.8.8
Submenu Logic Equations
2.8.8.1 Parameters
With the Logic Equations submenu, it is possible to form complex Boolean functions using
NOT, AND and OR operators (indicated from highest to lowest priority). Up to 16 operands
can be used in any single equation. The following logic signals are available for mapping to
an equation:
Function P721 P723 Information
Null X X the condition is null (low level)
Not Null X X the condition is not null (high level
[87] Diff X Phase differential protection threshold
[87N] Diff X X Earth differential protection threshold
[87] tDiff X Time delayed phase differential protection
threshold
[87N] tDiff X X Time delayed earth differential protection threshold
[87CZ] Check
zone X Check Zone status
[95] Sup X Phase high impedance differential threshold
(buswire supervision)
[95N] Sup X Earth high impedance differential threshold
(buswire supervision)
[95] tSup X Time delayed phase high impedance differential
threshold (buswire supervision)
[95N] tSup X X Time delayed earth high impedance differential
threshold (buswire supervision)
[95A] tSupA X Time delayed phase A (or L1, or R) high
impedance differential threshold (buswire
supervision)
[95B] tSupB X As above for phase B (or L2 or S)