M14964-1 v13
Table 77. Underfrequency protection SAPTOF
Function Range or Value Accuracy
Operate value, start function,
at symmetrical three phase
voltage,
StartFrequency
1)
(35.00 - 90.00) Hz ±2.0 mHz
Reset hysteresis
1)
10.0 mHz fixed ±2.0 mHz
Operate time
1)
fr = 50 Hz
Start time measurement with
sudden frequency change
Min. = 175 ms -
Max. = 195 ms
Start time measurement with
frequency ramp
Min. = 70 ms
Max. = 90 ms
fr = 60 Hz
Start time measurement with
sudden frequency change
Min. = 150 ms -
Max. = 165 ms
Start time measurement with
frequency ramp
Min. = 60 ms
Max. = 75 ms
Disengaging time
1)
fr = 50 Hz
Start time measurement with
sudden frequency change
Min. = 20 ms -
Max. = 30 ms
Start time measurement with
frequency ramp
Min. = 75 ms
Max. = 100 ms
fr = 60 Hz
Start time measurement with
sudden frequency change
Min. = 20 ms -
Max. = 30 ms
Start time measurement with
frequency ramp
Min. = 65 ms
Max. = 90 ms
Operate time delay,
tDelay
1)
fr = 50 Hz
(0.000-60.000)s
±0.2% or ±200 ms
whichever is greater
fr = 60 Hz ±0.2% or ±175 ms
whichever is greater
Note: The stated accuracy is valid for the voltage range 50 V – 250 V secondary.
1) The settings and test conditions are in accordance with IEC 60255-181 standard (section 6.2 – 6.7).
M14976-1 v10
Table 78. Rate-of-change of frequency protection SAPFRC
Function Range or value Accuracy
Operate value, start function (-10.00-10.00) Hz/s ±10.0 mHz/s
Operate value, restore enable frequency (45.00-65.00) Hz ±2.0 mHz
Definite restore time delay (0.000-60.000) s ±0.2% or ±100 ms whichever is greater
Definite time delay for frequency gradient
trip
(0.000-60.000) s ±0.2% or ±120 ms whichever is greater
Definite reset time delay (0.000-60.000) s ±0.2% or ±250 ms whichever is greater
Generator protection REG670
1MRK 502 074-BEN M
96 Hitachi Power Grids
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