GE P742

P74
x/EN ST/Na7
Settings
(ST) 4
-
16
MiCOM P74
1, P742, P743
ST
1.2.2 Differential Protection Configuration (“Busbar option” column – P741)
The differential element blockings and alarms can be configured to fit optimum operability,
they are used for all zones and the check zone independently.
This column is visible when the “Busbar Option” setting (“Configuration” column) = “visible”.
Menu Text Default Setting
Setting Range
Step Size
Min. Max.
BUSBAR OPTION
CZ Circ Flt Mode Alarm & No Block AlarmSR&No Block / Alarm & No Block
Self-Reset / Alarm Latched /
Blocking Latched
Check Zone Circuitry Fault:
Options for the Check Zone differential element faulty calculation due to wrong position of
CB or isolator or CT failure are as follow:
AlarmSR&No Block (Alarm Self Reset and No blocking):
The CZ does not block any zone trip and the alarm disappears as soon as the CZ
calculation is right.
Alarm & No Block (Alarm and No blocking):
The CZ does not block any zone trip and the alarm disappears only after manual reset.
Self-Reset:
The CZ blocks any zone trip and both the blocking and the alarm disappear as soon as the
CZ calculation is right.
Alarm Latched:
The CZ blocks any zone trip, the blocking disappe
ars as soon as the CZ calculation is right
but the alarm disappears only after manual reset.
Blocking Latched:
The CZ blocks any zone trip and both the blocking and the alarm disappear only after
manual reset.
Zx Circ Flt Mode Blocking Latched Self-Reset / Alarm Latched /
Blocking Latched / Alarm&NoBlock !!! /
AlmSR&NoBlck !!!
Zone x Circuitry Fault: Options for all the Zones differential element faulty calculation due to
wrong position of CB or isolator or CT failure are as follow:
Self-Reset:
The Zo
ne is blocked and both the blocking and the alarm disappear as soon as the Zone
calculation is right.
Alarm Latched:
The Zone is blocked, the blocking disappears as soon as the Zone calculation is right but
the alarm disappears only after manual reset.
Blocking Latched:
The Zone is blocked and both the blocking and the alarm disappear only after manual
reset.
AlarmSR&No Blck !!! (Alarm Self Reset and No blocking):
The Zone is not blocked and alarm disappears as soon as the zone calculation is right.
Alarm & No Block !!!:
The Zone is not blocked and alarm disappears only after manual reset.
The selection of “AlarmSR&No Blck !!!” or “Alarm & No Block !!!” modes
is effective only if no blocking zone is selected for Check zone circuitry
fault (CZ).
When “AlarmSR&No Blck !!!” or “Alarm & No Block !!!” setting is
selected, the protection will trip the related zone in case of an external
trip.