VAMP 259 - Page 116

2.18 Rate of change of frequency
(ROCOF) protection df/dt (81R)
2 Protection functions
Technical description
116
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VM259.EN007
Setting parameters of df/dt stage:
Parameter
Value
Unit
Default
Description
df/dt
0.2 ... 10.0
Hz/s
5.0
df/dt pick-up setting
t>
0.14 … 10.0
s
0.50
df/dt operational delay
t
Min
>
0.14 … 10.0
s
0.50
df/dt minimum delay
S_On
Enabled;
Disabled
-
Enabled
Start on event
S_Off
Enabled;
Disabled
-
Enabled
Start off event
T_On
Enabled;
Disabled
-
Enabled
Trip on event
T_Off
Enabled;
Disabled
-
Enabled
Trip off event
Measured and recorded values of df/dt stage:
Parameter
Value
Unit
Description
Measured
value
f
Hz
Frequency
df/dt
Hz/s
Frequency rate of
change
Recorded
values
SCntr
-
Start counter (Start)
reading
TCntr
-
Trip counter (Trip)
reading
Flt
%Hz/s
Max rate of change
fault value
EDly
%
Elapsed time as
compared to the set
operating time, 100%
= tripping