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3-62
Protection Functions
Note: The slope and operation delay
settings define the knee points on the
left. A common setting for t
been used in these three examples.
This minimum delay parameter defines
the knee point positions on the right.
Note: The time to trip will be 0.3 s,
although the setting is 0.6 s,
because the average slope 1 Hz/s
is steeper than the setting value
0.5 Hz/s.
857-UM001A-EN-P – July 2009
has
Min
Figure 3.30 – Three examples of possible inverse df/dt operation time characteristics
FREQUENCY
(Hz)
50.0
49.7
START
TRIP
Figure 3.31 – Example of inverse df/dt operation time
Table 3.36 – Setting Parameters of df/dt Stage
Parameter
df/dt
t>
t
>
Min
S_On
S_Off
T_On
T_Off
Settings:
0.00
0.15
0.30
0.45
Value
Unit
0.2 ... 10.0
Hz/s
5.0
0.14 ... 10.0
s
0.50
0.14 ... 10.0
s
0.50
Enabled;
-
Enabled
Disabled
Enabled;
-
Enabled
Disabled
Enabled;
-
Enabled
Disabled
Enabled;
-
Enabled
Disabled
ROCOF3_v3
df/dt = 0.5 Hz/s
t = 0.60 s
t
= 0.15 s
Min
TIME
(s)
0.60
Default
Description
df/dt pick-up setting
df/dt operational delay
df/dt minimum delay
Start on event
Start off event
Trip on event
Trip off event
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