GE P741

A
pplication Notes P74x/EN AP/N
a7
MiCOM P74
1, P742, P743 (AP) 6-
43
AP
Check zone Idiff = I
7
+ I
8
+ I
10
+ I
11
= i
diff
Z3 = i
fault
> (I
D
CZ>2 + kCZ x I
Bias
)
After the coupling breaker has been tripped:
Zone 1 Idiff = I7+ I8=idiffZ1 = ifault > (ID>2 + k2 x IBias)
Zone 2 Idiff = I10+ I11= idiffZ2 = 0
Check zone Idiff = I7+ I8+ I10+ I11= idiffZ1 = ifault > (IDCZ>2 + kCZ x IBias)
Note 1: As the topology algorithm scheme updates every 16ms. The longest
time to updates the topology after Isolator auxiliary contacts change
state is 33ms.
Note 2: For the Differential Busbar protection, the status positions of the
Breakers are not taken into account.