Table 144: SAPTOF Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 - 12 - 1 1 Selection of one of the Global Base
Value groups
10.2.6 Operation principle
M14958-3 v7
Overfrequency protection SAPTOF is used to detect high power system frequency.
SAPTOF has a settable definite time delay. If the frequency remains above the set
value for a time period corresponding to the chosen time delay, the corresponding
TRIP signal is issued. To avoid an unwanted TRIP due to uncertain frequency
measurement at low voltage magnitude, a voltage controlled blocking of the
function is available, that is, if the voltage is lower than the set blocking voltage
IntBlockLevel, the function is blocked and no START or TRIP signal is issued.
10.2.6.1 Measurement principle
M14958-6 v9
The fundamental frequency of the positive sequence voltage is measured
continuously, and compared with the set value, StartFrequency. Overfrequency
protection SAPTOF is dependent on the voltage magnitude. If the voltage
magnitude decreases below the setting IntBlockLevel, SAPTOF is blocked and the
output BLKDMAGN is issued. All voltage settings are made in percent of the
UBase, which should be set as a phase-phase voltage in kV. To avoid oscillations of
the output START signal, a hysteresis has been included.
10.2.6.2 Time delay
M14958-9 v8
The time delay for Overfrequency protection SAPTOF is a settable definite time
delay, specified by the setting tDelay.
TRIP signal issuing requires that the overfrequency condition continues for at least
the user set time delay, tDelay. If the START condition, with respect to the
measured frequency ceases during this user set delay time, and is not fulfilled again
within a user defined reset time, tReset, the START output is reset, after that the
defined reset time has elapsed. It is to be noted that after leaving the hysteresis
area, the START condition must be fulfilled again and it is not sufficient for the
signal to only return back to the hysteresis area.
The total time delay consists of the set value for time delay plus
minimum operate time of the start function (80 - 90 ms).
1MRK 505 394-UEN A Section 10
Frequency protection
Line differential protection RED650 2.2 IEC 275
Technical manual
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