GE P741

P74
x/EN ST/Na7
Settings
(ST) 4
-
18
MiCOM P74
1, P742, P743
ST
Menu Text Default Setting
Setting Range
Step Size
Min. Max.
BUSBAR OPTION
SEF Block Alarm Enabled Enabled / Disabled
Options for Sensitive Differential Earth Fault (SEF) Protection (87BB/N) only are as follow:
Enabled:
If the Sensitive Differential Earth Fault Protection (87BB/N) is blocked, the associated alarm
is raised and is flashing on the front panel of the P741.
Disabled:
If the Sensitive Differential Earth Fault Protection (87BB/N) is blocked, the associated alarm
is not raised and is not present on the front panel of the P741.
Confirm Reset PU Enabled Enabled / Disabled
Enables or disables the PU error auto- reset.
3ph Block-Alarm Enabled Enabled / Disabled
When enabled, an alarm is displayed when one zone is blocked by a
Differential Busbar
Protection function (87BB).
Delay Trip Status Disabled Enabled / Disabled
Activate or deactivat
e a time delay before 87BB (phase differential busbar protection) trip.
When activated, the settable delay time (using ‘Delay Trip Timer’ menu) is used to confirm
the fault or to clear the fault before zone trip.
Delay Trip Timer 0.1s 50ms 5s 10ms
‘Delay
Trip Timer’ sets the delay time to confirm a phase differential busbar protection
(87BB) trip when ‘Delay Trip Status’ is enabled. This delay time must be shorter than the
time delay of phase circuitry fault monitoring (‘DIFF BUSBAR PROT / ID>1 Alarm time
r’
menu).
Diff Display Min 0A 0A 500A 10A
Sets a minimum threshold to display a differential current (‘Measurement’ column). When
the differential current is less than this threshold on the 3 phases, the displayed current is
forced to 0.
1.2.3 Busbar Trip (87BB) or Central Breaker Fail BackTrip Confirmation (50BF) (“BB Trip Confirm”
menu – P742/P743)
The peripheral units can be enabled to control the trip command issue by the central unit
(87BB or 50BF) if a local fault threshold, either phase or earth (i.e. I>BB or I
N
>BB), is
exceeded.
This criterion provides additional scheme stability. Should the command proceed, and a trip
be issued to the circuit breaker this element can confirm the evolution of a circuit breaker
failure condition. If the element is still operated after a set time delay a breaker failure
condition must exist.
Menu Text Default Setting
Setting Range
Step Size
Min. Max.
BB Trip Confirm
I>BB Current Set 1.20*I
n
0.05*I
n
4.00*I
n
0.01*I
n
Setting for the minimum pickup phase fault element trip authorization
I
N
>BB Current 0.20*I
n
0.05*I
n
4.00*I
n
0.01*I
n
Setting for the minimum pickup Earth fault element trip authorization
Note: I
n
is the CT nominal current.