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Functions
Definite-Time
Trip Stage
I
L1
I
L2
I
L3
FNo. 05146
>RM th.rep. I2
FNo. 05143
>BLOCK I2
Figure 2-22
Logic Diagram of the Unbalanced Load Protection
66
High negative phase-sequence currents can only be caused by a two-pole power
system short circuit which must be covered in accordance with the network grading
plan. For this reason, the thermal characteristic is cut by a selectable, definite-time,
negative phase-sequence current stage (address 1706 I2>> and 1707 T I2>>)
(see Figure 2-21).
Please also observe the instructions regarding the phase rotation (phase sequence)
provided in Sections 2.3 and 2.43.
t
T WARN
T I2>>
I
2 adm
Figure 2-21
Tripping Zone of the Unbalanced Load Protection
I
2
1
å
I
CO
0
OR
1702 I2>
1705 I2>>
Unbalanced load stage I
2adm.
Thermal
trip stage
1704 FACTOR K
2
I
⋅
2
-- -
t ∆
I
n
Reset
I
=0
2
1703 T WARN
&
1707 T I2>>
&
Unbalanced load
Tripping zone I
>>
2
I
I
>>
2
2
FNo.05161
I2 Q TRIP
&
FNr.05158
Tripping
RM th.rep. I2
matrix
FNr.05165
I2> picked up
FNr.05156
I2> Warn
TMin
TRIP CMD
FNr.05160
I2>> TRIP
FNr.05159
I2>> picked up
FNr.05152
I2 BLOCKED
7UM62 Manual
C53000-G1176-C149-3
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