81R Frequency Protection – "df/dt"
Reference
Parameter Value
df/dt
set
df/dt setting 0.050 to 10 Hz/s
Direction Both, positive, negative
df/dt Applied rate of frequency (for operate
time)
0 to 1.3 ⋅ df/dt
set
(switched)
0 to 2 ⋅ df/dt
set
(switched)
t
delay
Delay setting 0 to 20 s, Δ 0.01 s
20 to 200 s, Δ 0.1 s
Operate and Reset Level
Attribute Value
df/dt
op
Operate level df/dt
set
± 50 MHz/s (f
rated
± 3 Hz
Repeatability ± 1 %
Variation IEC
60255-1
-10 °C to +55 °C ≤ 5 %
f
rated
± 5 % ≤ 5 %
Operate and Reset Time
Attribute
Value
t
basic
Element basic operate time
(for ROCOF ˃ 1.3x setting)
Typically < 215 ms
Maximum < 300 ms
Element basic operate time
(for ROCOF ˃ 2x setting)
Typically < 185 ms
Maximum < 200 ms
t
op
Operate time following delay t
basic
+ t
delay
± 1 % or ± 10 ms
Repeatability ± 1 % or ± 10 ms
10.36
Technical Data
10.36 81R Frequency Protection – "df/dt"
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual 551
C53000-G7040-C014-1, Edition 11.2019
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